BSI 21/30427944 DC:2021 Edition
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BS 1377-2. Methods of test for soils for civil engineering purposes – Part 2. Classification tests and determination of geotechnical properties
| Published By | Publication Date | Number of Pages |
| BSI | 2021 | 159 |
PDF Catalog
| PDF Pages | PDF Title |
|---|---|
| 1 | 30427944.PDF |
| 3 | 30427944draft.pdf |
| 7 | 1 Scope 2 Normative references 3 Terms and definitions |
| 8 | 4 Determination of water content 4.1 Oven-drying method 4.2 Method for saturation water content of chalk 4.2.1 General 4.2.2 Apparatus 4.2.3 Procedure |
| 9 | 4.2.4 Calculations and expression of results 4.2.5 Test report The test report shall affirm that the test was carried out in accordance with BS EN ISO 17892-2 and calculated in accordance with this British Standard, 4.2. The test report shall contain the following information: 5 Determination of the liquid limit 5.1 General |
| 10 | 5.2 Cone penetrometer method (definitive method) 5.3 One-point cone penetrometer method 5.3.1 General 5.3.2 Calculations and expression of results |
| 11 | 5.3.3 Test report 5.4 Casagrande apparatus method 5.5 One-point Casagrande method 5.5.1 General 5.5.2 Calculations and expression of results |
| 12 | 5.5.3 Test report 6 Determination of the plastic limit and plasticity index 6.1 General 6.2 Additional parameters 7 Determination of shrinkage characteristics 7.1 Linear shrinkage 7.1.1 General |
| 13 | 7.1.2 Apparatus 7.1.2.1 Two palette knives or spatulas. 7.1.2.2 A flat, glass plate, a convenient size being 10 mm thick and about 500 mm square, or an evaporating dish of approximately 150 mm diameter. 7.1.2.3 A mould made of brass, or other suitable material complying with the essential details illustrated in Figure 1. 7.1.2.4 Silicone grease or petroleum jelly. 7.1.2.5 A drying oven, capable of maintaining temperatures of 60 C to 65 C and of 105 C to 110 C. 7.1.2.6 A means of measuring a length of up to 150 mm to within 0.5 mm, such as an engineers’ steel rule or vernier callipers. 7.1.2.7 Distilled or de-ionized water, complying with BS 1377-1:2016, 6.1. 7.1.3 Preparation of apparatus Clean the mould thoroughly and apply a thin film of silicone grease or petroleum jelly to its inner faces to prevent the soil adhering to the mould. 7.1.4 Procedure 7.1.4.1 Place a specimen of about 150 g from the material passing through the 425 µm test sieve, obtained as specified in BS EN ISO 17892-12:2018, 5.2, on the flat, glass plate or in the evaporating dish. 7.1.4.2 Add distilled/deionized water if necessary and mix thoroughly using the palette knives until the mass becomes a smooth homogeneous paste with a water content at about the liquid limit of the soil. |
| 14 | 7.1.4.3 Place the soil/water mixture in the mould such that it is slightly proud of the sides of the mould. Gently jar the mould to remove any air pockets in the mixture. 7.1.4.4 Level the soil along the top of the mould with the palette knife and remove all soil adhering to the rim of the mould by wiping with a damp cloth. 7.1.4.5 Place the mould where the soil/water can air dry slowly in a position free from draughts until the soil has shrunk away from the walls of the mould. Then complete the drying, first at a temperature not exceeding 65 C until shrinkage has large… 7.1.4.6 Remove from the oven and place in a desiccator with dry self-indicating desiccant. When cool, measure the mean length of the soil bar. If the specimen has become curved during drying, remove it carefully from the mould and measure the lengths … 7.1.5 Calculations and expression of results 7.1.6 Test report The report shall affirm that the test was carried out in accordance with this British Standard, 7.1 and shall include the following information: 8 Determination of density |
| 15 | Density tests shall be performed in accordance with one of the three test methods prescribed in BS EN ISO 17892-2. 9 Determination of particle density 9.1 General The particle density shall be determined using a pycnometer in accordance with BS EN ISO 17892-3 either by fluid displacement or by gas displacement, or by the gas jar method in accordance with 9.2 of this British Standard. 9.2 Gas jar method 9.2.1 General 9.2.2 Sample preparation 9.2.2.1 Sample. A sample of soil of about 1 kg mass shall be obtained as specified in BS 1377-1:2016, 8.3 and 8.4.4. Coarse material in excess of 10% retained on a 37.5 mm test sieve, or any particles retained on a 50 mm test sieve, shall be broken do… 9.2.2.2 Test specimens. At least two specimens shall be obtained from the sample by riffling. For fine-grained soils, each specimen shall be of about 200 g, and for coarse-grained soils of about 400 g. The specimens shall be oven dried, normally at 10… 9.2.3 Apparatus 9.2.3.1 A gas jar, 1 L in capacity, fitted with a rubber bung. 9.2.3.2 A ground glass plate, for closing the gas jar. 9.2.3.3 A mechanical shaking apparatus, capable of rotating the gas jar, end over end, at about 50 revolutions per minute. |
| 16 | 9.2.3.4 A balance, readable to 0.1 g. 9.2.3.5 A thermometer, to cover the temperature range 0 C to 50 C, readable to 1 C. 9.2.3.6 A drying oven, capable of maintaining a temperature of 105 C to 110 C. 9.2.4 Procedure 9.2.4.1 Clean and dry the gas jar and ground glass plate and weigh them together to the nearest 0.2g (m1). 9.2.4.2 Transfer the first soil specimen from its sealed container directly into the gas jar. Weigh the gas jar, ground glass plate and contents to the nearest 0.2 g (m2). 9.2.4.3 Add about 500 mL of water at a temperature within ±2 C of the average room temperature during the test to the soil. Insert the rubber stopper into the gas jar, and for medium- and coarse-grained soils (as defined in BS 1377-1:2016, Clause 4) … 9.2.4.4 At the end of this period, or immediately after the addition of water in the case of fine-grained soils, shake the gas jar by hand until the particles are in suspension. 9.2.4.5 Place the gas jar securely in the shaking apparatus and shake for a period of 20 min to 30 min. 9.2.4.6 Remove the stopper carefully and wash any soil particles adhering to the stopper or to the top of the gas jar into the jar. Disperse any froth with a fine spray of water. Add water to the gas jar to within 2 mm of the top and allow the soil to… 9.2.4.7 Dry the gas jar and plate carefully on the outside and weigh the whole to the nearest 0.2 g (m3). 9.2.4.8 Empty the gas jar, wash it out thoroughly and fill it to the brim with water at a temperature within ±2 C of the average room temperature. Place the ground glass plate in position taking care not to trap any air under the plate. Ensure that t… 9.2.4.9 Dry the gas jar and plate carefully on the outside and weigh the whole to the nearest 0.2 g (m4). 9.2.4.10 Repeat 9.2.4.1 to 9.2.4.7 using the second specimen of the same soil so that two values of particle density can be obtained. If the results differ by more than 0.03 Mg/m3 repeat the tests. 9.2.5 Calculations and expressions of results |
| 17 | 9.2.6 Test report The test report shall affirm that the test was carried out in accordance with this British Standard, 9.2 and shall include the following information: 10 Determination of particle size distribution 11 Determination of dry density/water content relationship 11.1 General |
| 18 | Three types of compaction test are described, each with procedural variations related to the nature of soil. The first is the light compaction test in which a 2.5 kg rammer is used. The second is the heavy manual compaction test which gives a much gre… |
| 19 | 11.2 Preparation of samples for compaction tests 11.2.1 General Preliminary assessment. The initial soil sample for testing shall be obtained in accordance with the procedure described in BS 1377-1:2016, 8.6.1 to 8.6.3. The procedures to be used for sample preparation and for carrying out the compaction test shall… |
| 20 | Table 3 – Summary of sample preparation procedures |
| 22 | 11.2.2 Apparatus 11.2.2.1 Test sieves, with aperture sizes 63 mm, 37.5 mm, 20 mm, with receiver. 11.2.2.2 A balance, readable to 5 g. 11.2.2.3 A balance, readable to 1 g. 11.2.2.4 A corrosion-resistant metal or plastics tray with sides, e.g. about 80 mm deep, of a size suitable for the quantity of material to be used. 11.2.2.5 A large metal scoop. 11.2.2.6 A palette knife or spatula. 11.2.2.7 Watertight containers, e.g. strong polythene bags. 11.2.2.8 Apparatus for determination of water content, as described in BS EN ISO 17892-1. 11.2.2.9 An implement for shredding stiff soil. 11.2.3 Preparation of soils for compaction in 1 L mould 11.2.3.1 Grading zone (1) for soils passing a 20 mm test sieve not susceptible to crushing 11.2.3.1.1 Prepare and subdivide the initial sample by the procedures described in BS 1377-1:2016, 8.6, to produce a representative specimen of about 6 kg of the soil. 11.2.3.1.2 Add a suitable amount of water depending on the soil type and mix thoroughly. 11.2.3.1.3 If the soil initially contains too much water, allow it to partially air dry to the lowest water content at which the soil is to be compacted, and mix thoroughly. 11.2.3.1.4 If the soil is fine, seal in an airtight container and store for at least 24 h. 11.2.3.2 Grading zone (1) for soils passing a 20 mm sieve susceptible to crushing |
| 23 | 11.2.3.3 Grading zone (2) for soils passing the 37.5 mm test sieve with at least 95% passing a 20 mm test sieve not susceptible to crushing 11.2.3.3.1 Weigh to 0.1% by mass the whole sample and record the mass. 11.2.3.3.2 Remove and weigh to 0.1% by mass the material retained on the 20 mm test sieve. 11.2.3.3.3 Subdivide the finer material and proceed as described in 11.2.3.1. 11.2.3.4 Grading zone (2) for soils passing the 37.5 mm test sieve with at least 95% passing a 20 mm test sieve susceptible to crushing 11.2.4 Preparation of soils in a CBR mould 11.2.4.1 Grading zone (3) for soils passing the 37.5 mm test sieve with 70% to 95% passing a 20 mm test sieve not susceptible to crushing Prepare and subdivide the initial sample using the procedure described in BS 1377-1:2016, 8.6 to produce a representative specimen of about 15 kg of the soil, otherwise proceed as described in 11.2.3.1. 11.2.4.2 Grading zone (3) for soils passing the 37.5 mm test sieve with 70% to 95% passing a 20 mm test sieve susceptible to crushing 11.2.4.3 Grading zone (4) for soils containing at least 95% passing the 37.5 mm test sieve and at least 70% passing a 20 mm test sieve not susceptible to crushing 11.2.4.3.1 Weigh the whole sample and record the mass to the nearest 5 g. 11.2.4.3.2 Remove and weigh the material retained on the 37.5 mm test sieve. |
| 24 | 11.2.4.3.3 Subdivide the finer material to produce a 15 kg specimen, otherwise proceed as described in 11.2.3.1. 11.2.4.4 Grading zone (4) for soils containing at least 95% passing the 37.5 mm test sieve and at least 70% passing the 20 mm test sieve susceptible to crushing 11.2.4.5 Grading zone (5) for soils with 90% to 95% passing the 37.5 mm test sieve, and at least 70% passing a 20 mm test sieve not susceptible to crushing 11.2.4.5.1 Weigh the soil sample to the nearest 5 g. 11.2.4.5.2 Remove and weigh the material retained on the 37.5 mm test sieve. 11.2.4.5.3 Replace this material by the same quantity of material of similar characteristics that passes the 37.5 mm test sieve and is retained on the 20 mm test sieve. 11.2.4.5.4 Subdivide the material to produce a specimen of approximately 15 kg of the soil, otherwise proceed as described in 11.2.3.1. 11.2.4.6 Grading zone (5) for soils containing 90% to 95% passing the 37.5 mm test sieve and at least 70% passing a 20 mm test sieve susceptible to crushing 11.3 Compaction method using 2.5 kg rammer with 1 L mould 11.3.1 General 11.3.2 Apparatus 11.3.2.1 A cylindrical, corrosion-resistant metal mould, i.e. the compaction mould, having a nominal internal volume of 1 L. The mould shall be fitted with a detachable baseplate and a removable extension. The essential dimensions are shown in Figure … |
| 25 | 11.3.2.2 A metal rammer, having a 50 ± 0.5 mm diameter circular face, and weighing 2.5 kg ±25 g. The rammer shall be equipped with a suitable arrangement for controlling the height of drop to 300 ±3 mm. One suitable form of hand apparatus is shown in … 11.3.2.3 A balance readable to 1 g. 11.3.2.4 A palette knife or spatula. 11.3.2.5 A straightedge, e.g. a steel strip about 300 mm long, 25 mm wide, and 3 mm thick, with one bevelled edge. 11.3.2.6 Test sieves, of aperture sizes 37.5 mm and 20 mm and a receiver. 11.3.2.7 A corrosion-resistant metal or plastics tray with sides, e.g. about 80 mm deep, of a size suitable for the quantity of material to be used. 11.3.2.8 Apparatus for water content determination, as described in BS EN ISO 17892-1. |
| 28 | 11.3.3 Preparation of sample Prepare the test sample as described in 11.2.3.1, 11.2.3.2, 11.2.3.3 or 11.2.3.4 as appropriate. 11.3.4 Procedure 11.3.4.1 Compaction procedure for soil particles not susceptible to crushing 11.3.4.1.1 Weigh the mould with baseplate attached to 1 g (m1). Measure the internal dimensions to 0.1 mm. 11.3.4.1.2 Attach the extension to the mould and place the mould assembly on a solid base, e.g. a concrete floor or plinth. 11.3.4.1.3 Place a quantity of moist soil in the mould such that when compacted it occupies a little over one-third of the height of the mould body. 11.3.4.1.4 Apply 27 blows from the rammer dropped from a height of 300 mm above the soil as controlled by the guide tube. Distribute the blows uniformly over the surface and ensure that the rammer always falls freely and is not obstructed by soil in t… 11.3.4.1.5 Repeat 11.3.4.1.3 and 11.3.4.1.4 twice more, so that the amount of soil used is sufficient to fill the mould body, with the surface not more than 6 mm proud of the upper edge of the mould body. 11.3.4.1.6 Remove the extension, strike off the excess soil and level off the surface of the compacted soil carefully to the top of the mould using the straightedge. Replace any coarse particles, removed in the levelling process, by finer material fro… 11.3.4.1.7 Weigh the soil and mould with baseplate to 1 g (m2). 11.3.4.1.8 Remove the compacted soil from the mould and place it on the metal tray. Take a representative specimen of the soil for determination of its water content as described in BS EN ISO 17892-1. 11.3.4.1.9 Break up the remainder of the soil, rub it through the 20 mm test sieve and mix with the remainder of the prepared test specimen. 11.3.4.1.10 Add a suitable increment of water and mix thoroughly into the soil. |
| 29 | 11.3.4.1.11 Repeat 11.3.4.1.3 to 11.3.4.1.10 to give a total of at least five determinations. The water contents shall be such that the optimum water content, at which the maximum dry density occurs, lies near the middle of the range. 11.3.4.2 Compaction procedure for soil particles susceptible to crushing 11.3.4.2.1 Weigh, measure and prepare the mould as described in 11.3.4.1.1 and 11.3.4.1.2. 11.3.4.2.2 Carry out a compaction test on each of the prepared specimens as described in 11.3.4.1.3 to 11.3.4.1.8. 11.3.4.2.3 Discard the remainder of each compacted specimen. 11.3.5 Calculations, plotting and expression of results 11.3.5.1 Calculate the internal volume, V (in cm3), of the mould. 11.3.5.2 Calculate the bulk density, p (in Mg/m3), of each compacted specimen from the formula: 11.3.5.3 Calculate the dry density, ρd (in Mg/m3), of each compacted specimen from the formula: 11.3.5.4 Plot the dry densities obtained from a series of determinations as y-axis against the corresponding water contents on the x-axis. Draw a curve of best fit to the plotted points and identify the position of the maximum on this curve. Read off … 11.3.5.5 On the same graph, plot the curves corresponding to 0%, 5% and 10% air voids, calculated from the formula: |
| 30 | 11.3.6 Test report The test report shall affirm that the test was carried out in accordance with this British Standard, 11.3 and shall contain the following information: 11.4 Compaction method using 2.5 kg rammer with CBR mould 11.4.1 General |
| 31 | 11.4.2 Apparatus 11.4.2.1 A cylindrical, corrosion-resistant, metal mould, i.e. the CBR mould, with a detachable baseplate and a removable extension as described in 15.2.2.2. 11.4.2.2 A hand or motorized, metal rammer, having a 50 mm diameter circular face, and weighing 2.5 kg, as described in 11.3.2.2. 11.4.2.3 A balance readable to 5 g. 11.4.2.4 A large scoop. 11.4.2.5 Other items, as specified in 11.3.2.4 to 11.3.2.9. 11.4.3 Preparation of specimen 11.4.4 Procedure 11.4.4.1 Compaction procedure for soil particles not susceptible to crushing 11.4.4.1.1 Weigh the CBR mould with baseplate attached, to 5 g (m1). Measure the internal dimensions to 0.5 mm. 11.4.4.1.2 Attach the extension to the mould and place the mould assembly on a solid base, e.g. a concrete floor or plinth. 11.4.4.1.3 Place a quantity of moist soil in the mould such that when compacted it occupies a little over one-third of the height of the mould body. 11.4.4.1.4 Apply 62 blows from the rammer dropped from a height of 300 mm above the soil. Distribute the blows uniformly over the surface and ensure that the rammer always falls freely and is not obstructed by soil in the guide tube, see [3]. 11.4.4.1.5 Repeat 11.4.4.1.3 and 11.4.4.1.4 twice more, so that the amount of soil is sufficient to fill the mould body, with the surface not more than 6 mm proud of the upper edge of the mould body. 11.4.4.1.6 Remove the extension, strike off the excess soil and level off the surface of the compacted soil carefully to the top of the mould using the straightedge. Any coarse particles removed in the levelling process shall be replaced by finer mate… 11.4.4.1.7 Weigh the soil and mould with baseplate to 5 g (m2). 11.4.4.1.8 Remove the compacted soil from the mould and place it on the metal tray. Take a representative specimen of the soil for determination of its water content as described in BS EN ISO 17892-1. 11.4.4.1.9 Break up the remainder of the soil, rub it through the 20 mm or the 37.5 mm test sieve and mix with the remainder of the prepared test specimen. 11.4.4.1.10 Add a suitable increment of water and mix thoroughly into the soil. |
| 32 | 11.4.4.1.11 Repeat 11.4.4.1.3 to 11.4.4.1.10 to give a total of at least five determinations. The water contents shall be such that the optimum water content, at which the maximum dry density occurs, lies near the middle of the range. 11.4.4.2 Compaction procedure for soil particles susceptible to crushing 11.4.4.2.1 Weigh, measure and prepare the CBR mould as described in 11.4.4.1.1 and 11.4.4.1.2. 11.4.4.2.2 Carry out a compaction test on each of the prepared specimens in turn as described in 11.4.4.1.3 to 11.4.4.1.8. 11.4.4.2.3 Discard the remainder of each compacted specimen. 11.4.5 Calculations For plotting and expression of results, proceed as described in 11.3.5. 11.4.6 Test report The test report shall comply with 11.3.6. 11.5 Compaction method using 4.5 kg rammer with 1 L mould 11.5.1 General 11.5.2 Apparatus 11.5.2.1 A cylindrical corrosion-resistant metal mould, i.e. the 1 L compaction mould, as specified in 11.3.2.1. 11.5.2.2 A metal rammer, having a 50 ±0.5 mm diameter circular face, and weighing 4.5 kg ±50 g. The rammer shall be equipped with a suitable arrangement for controlling the height of drop to 450 ±4 mm. One suitable form of hand apparatus is shown in F… |
| 33 | 11.5.3 Preparation of specimen Prepare the test specimen as described in 11.2.3.1, 11.2.3.2, 11.2.3.3 or 11.2.3.4 as appropriate. |
| 34 | 11.5.4 Procedure 11.5.4.1 Compaction procedure for soil particles not susceptible to crushing 11.5.4.1.1 Weigh the mould with baseplate attached to 1 g (m1). Measure the internal dimensions to 0.1 mm. 11.5.4.1.2 Attach the extension to the mould and place the mould assembly on a solid base, e.g. a concrete floor or plinth. 11.5.4.1.3 Place a quantity of moist soil in the mould such that when compacted it occupies a little over one-fifth of the height of the mould body. 11.5.4.1.4 Apply 27 blows from the rammer dropped from a height of 450 mm above the soil as controlled by the guide tube. Distribute the blows uniformly over the surface and ensure that the rammer always falls freely and is not obstructed by soil in t… 11.5.4.1.5 Repeat 11.5.4.1.3 and 11.5.4.1.4 four more times, so that the amount of soil used is sufficient to fill the mould body, with the surface not more than 6 mm proud of the upper edge of the mould body. (See Note to 11.3.4.1.5.) 11.5.4.1.6 Remove the extension, strike off the excess soil and level off the surface of the compacted soil carefully to the top of the mould using the straightedge. Replace any coarse particles, removed in the levelling process, by finer material fro… 11.5.4.1.7 Weigh the soil and mould with baseplate to 1 g (m2). 11.5.4.1.8 Remove the compacted soil from the mould and place it on the large metal tray. Take a representative specimen of the soil for determination of its water content as described in BS EN ISO 17892-1. 11.5.4.1.9 Break up the remainder of the soil, rub it through the 20 mm test sieve and mix with the remainder of the prepared test specimen. 11.5.4.1.10 Add a suitable increment of water (see Note to 11.3.4.1.10) and mix it thoroughly into the soil. 11.5.4.1.11 Repeat 11.5.4.1.3 to 11.5.4.1.10 to give a total of at least five determinations. The water contents shall be such that the optimum water content, at which the maximum dry density occurs, lies near the middle of the range. 11.5.4.2 Compaction procedure for soil particles susceptible to crushing 11.5.4.2.1 Weigh, measure and prepare the mould as described in 11.5.4.1.1 and 11.5.4.1.2. 11.5.4.2.2 Carry out a compaction test on each of the prepared specimens in turn as described in 11.5.4.1.3 to 11.5.4.1.8. 11.5.4.2.3 Discard the remainder of each compacted specimen. 11.5.5 Calculations 11.5.6 Test report 11.6 Method using 4.5 kg rammer with CBR mould |
| 35 | 11.6.1 General 11.6.2 Apparatus 11.6.2.1 A cylindrical, corrosion-resistant metal mould, i.e. the CBR mould, as described in 15.2.2.2. 11.6.2.2 A hand or motorized metal rammer weighing 4.5 kg, as described in 11.5.2.2. 11.6.2.3 A balance readable to 5 g. 11.6.2.4 A large scoop. 11.6.2.5 Other items, as specified in 11.3.2.4 to 11.3.2.9. 11.6.3 Preparation of specimen Prepare the test specimen as described in 11.2.4.1, 11.2.4.2, 11.2.4.3, 11.2.4.4, 11.2.4.5, or 11.2.4.6 as appropriate. 11.6.4 Procedure 11.6.4.1 Compaction procedure for soil particles not susceptible to crushing 11.6.4.1.1 Weigh the mould with baseplate attached to 5 g (m1). Measure the internal dimensions to 0.5 mm. 11.6.4.1.2 Attach the extension to the mould and place the mould assembly on a solid base, e.g. a concrete floor or plinth. 11.6.4.1.3 Place a quantity of moist soil in the mould such that when compacted it occupies a little over one-fifth of the height of the mould body. 11.6.4.1.4 Apply 62 blows from the rammer dropped from a height of 450 mm above the soil as controlled by the guide tube. Distribute the blows uniformly over the surface and ensure that the rammer always falls freely and is not obstructed by soil in t… 11.6.4.1.5 Repeat 11.6.4.1.3 and 11.6.4.1.4 four more times, so that the amount of soil used is sufficient to fill the mould body, with the surface not more than 6 mm proud of the upper edge of the mould body. (See Note to 11.4.4.1.5.) 11.6.4.1.6 Remove the extension, strike off the excess soil and level off the surface of the compacted soil carefully to the top of the mould using the straightedge. Replace any coarse articles, removed in the levelling process, by finer material from… 11.6.4.1.7 Weigh the soil and mould with baseplate to 5 g (m2). 11.6.4.1.8 Remove the compacted soil from the mould and place it on the large metal tray. Take a representative specimen of the soil for determination of its water content as described in BS EN ISO 17892-1. 11.6.4.1.9 Break up the remainder of the soil, rub it through the 20 mm or the 37.5 mm test sieve and mix with the remainder of the prepared test specimen. 11.6.4.1.10 Add a suitable increment of water (see Note to 11.4.4.1.10) and mix thoroughly into the soil. |
| 36 | 11.6.4.1.11 Repeat 11.6.4.1.3 to 11.6.4.1.10 to give a total of at least five determinations. The water contents shall be such that the optimum water content, at which the maximum dry density occurs, lies near the middle of the range. 11.6.4.2 Compaction procedure for soil particles susceptible to crushing 11.6.4.2.1 Weigh, measure and prepare the mould as described in 11.6.4.1.1 and 11.6.4.1.2. 11.6.4.2.2 Carry out a compaction test on each of the prepared specimens as described in 11.6.4.1.3 to 11.6.4.1.8. 11.6.4.2.3 Discard the remainder of each compacted specimen. 11.6.5 Calculations 11.6.6 Test report 11.7 Compaction method using vibrating hammer 11.7.1 General 11.7.2 Apparatus 11.7.2.1 A cylindrical, corrosion-resistant metal mould, i.e. the CBR mould, as described in 15.2.2.2. 11.7.2.2 An electric vibrating hammer, having a power consumption between 600 W and 800 W and operating at a frequency between 25 Hz to 60 Hz. |
| 37 | 11.7.2.3 A steel tamper for attachment to the vibrating hammer. Essential dimensions are shown in Figure 8(b), which also indicates one suitable design of tamper. 11.7.2.4 Supporting guide frame for vibrating hammer (optional). 11.7.2.5 A depth gauge or steel rule, or other device which enables the sample depth to be measured to an accuracy of 0.5 mm. 11.7.2.6 A balance, readable to 5 g. 11.7.2.7 A straightedge, e.g. a steel strip about 300 mm long, 25 mm wide, and 3 mm thick, with one bevelled edge. 11.7.2.8 Test sieves, of aperture sizes 37.5 mm and 20 mm, and receiver. 11.7.2.9 A corrosion-resistant metal or plastics tray with sides, e.g. about 80 mm deep, of a size suitable for the quantity of material to be used. 11.7.2.10 A scoop. 11.7.2.11 Apparatus for the determination of water content, as described in BS EN ISO 17892-1. 11.7.2.12 A stopclock, readable to 1 s. 11.7.2.13 Apparatus for extracting compacted specimens from the mould (optional). |
| 38 | 11.7.3 Calibration of vibrating hammer 11.7.3.1 General The vibrating hammer shall be maintained in accordance with the manufacturer’s instructions. Its working parts shall not be badly worn. |
| 39 | 11.7.3.2 Material 11.7.3.3 Calibration test 11.7.3.3.1 Take a 5 ±0.1 kg specimen of the sand specified in 11.7.3.2, which has not been used previously, and mix it with water in order to raise its water content to 2.5 ±0.5%. 11.7.3.3.2 Compact the wet sand in a cylindrical metal mould of 152 mm diameter and 127 mm depth, using the vibrating hammer as specified in 11.7.5.1. 11.7.3.3.3 Carry out a total of three tests, all on the same specimen of sand, and determine the mean dry density. Determine the dry density values to the nearest 0.002 Mg/m3. 11.7.3.3.4 If the range of values in the three tests exceeds 0.01 Mg/m3, repeat the procedure. Consider the vibrating hammer suitable for use in the vibrating compaction test if the mean dry density of the sand exceeds 1.74 Mg/m3. 11.7.3.4 Pressure check Apply pressure combined with vibration to ensure the required degree of compaction. A downward force on the specimen surface of 300 N to 400 N shall be applied, this being greater than the force needed to prevent the hammer bouncing on the soil. 11.7.4 Preparation of specimen Prepare the test specimen as described in 11.2.4.1, 11.2.4.2, 11.2.4.3, 11.2.4.4, 11.2.4.5 or 11.2.4.6 as appropriate. 11.7.5 Procedure 11.7.5.1 Compaction procedure for soil particles not susceptible to crushing 11.7.5.1.1 Weigh the mould, with baseplate and extension attached, to 5 g (m1). Measure the internal dimensions to 0.5 mm. 11.7.5.1.2 Attach the extension to the mould and place the mould assembly on a solid base, e.g. a concrete floor or plinth. 11.7.5.1.3 Place a quantity of moist soil in the mould such that when compacted it occupies a little over one-third of the height of the mould body. 11.7.5.1.4 Place the circular tamper on the soil and compact with the vibrating hammer for 60 ±2 s. During this period apply a steady downward force on the hammer so that the total downward force on the sample, including that from the mass of the hamm… |
| 40 | 11.7.5.1.5 Repeat 11.7.5.1.3 and 11.7.5.1.4 twice more. 11.7.5.1.6 Remove any loose material lying on the surface of the sample around the sides of the mould. 11.7.5.1.7 Lay a straightedge across the top of the extension collar and measure down to the surface of the sample to an accuracy of 0.5 mm. Take readings at four points spaced evenly over the surface of the sample, all at least 15 mm from the side of… 11.7.5.1.8 Weigh the soil and mould with baseplate and extension to 5 g (in m2). 11.7.5.1.9 Remove the compacted soil from the mould and place it on the metal tray. Take a representative specimen of the soil for determination of its water content as described in BS EN ISO 17892-1. 11.7.5.1.10 Break up the remainder of the soil, rub it through the 20 mm or the 37.5 mm test sieve and mix with the remainder of the prepared test specimen. 11.7.5.1.11 Add a suitable increment of water and mix thoroughly into the soil. 11.7.5.1.12 Repeat 11.7.5.1.3 to 11.7.5.1.11 to give a total of at least five determinations. The water contents shall be such that the optimum water content, at which the maximum dry density occurs, lies near the middle of the range. 11.7.5.2 Compaction procedure for soil particle susceptible to crushing 11.7.5.2.1 Weigh, measure and prepare the CBR mould as described in 11.7.5.1.1 and 11.7.5.1.2. 11.7.5.2.2 Carry out a compaction test on each of the prepared specimens in turn as described in 11.7.5.1.3 to 11.7.5.1.9. 11.7.5.2.3 Discard the remainder of each compacted specimen. 11.7.6 Calculations, plotting and expression of results 11.7.6.1 Calculate the bulk density, ρ (in Mg/m3), of each compacted specimen from the formula: |
| 41 | 11.7.6.2 Calculate the dry density, ρd (in Mg/m3), of each compacted specimen from the formula: 11.7.6.3 Plot the dry densities obtained from a series of determinations on the y-axis against the corresponding water contents on the x-axis. Draw a curve of best fit to the plotted points and identify the position of the maximum on this curve. Read … 11.7.6.4 On the same graph, plot the curves corresponding to 0%, 5% and 10% air voids, calculated from the formula: 11.7.7 Test report The test report shall affirm that the test was carried out in accordance with this Britsh Standard, 11.7 and shall contain the following information: |
| 42 | 12 Determination of maximum and minimum dry densities for coarse soils 12.1 Determination of maximum density of sands 12.1.1 General 12.1.2 Apparatus 12.1.2.1 A cylindrical, corrosion-resistant metal mould, i.e. the 1 L mould, with baseplate and extension, as described in 11.3.2.1. 12.1.2.2 An electric vibrating hammer, as specified in 11.7.2.2. 12.1.2.3 A steel tamper for attachment to the vibrating hammer. Essential dimensions are shown in Figure 8(a), which also indicates one suitable design of tamper. 12.1.2.4 Supporting guide frame for vibrating hammer (optional). 12.1.2.5 A watertight container, large enough to hold the compaction mould. 12.1.2.6 A balance, readable to 1 g. |
| 43 | 12.1.2.7 A straightedge, e.g. a steel strip about 300 mm long, 25 mm wide, and 3 mm thick, with one bevelled edge. 12.1.2.8 Test sieves, of aperture sizes 2 mm and 6.3 mm, and receiver. 12.1.2.9 A palette knife or spatula. 12.1.2.10 Large metal tray, with sides about 80 mm deep. 12.1.2.11 Small metal tray, with sides about 50 mm deep. 12.1.2.12 A bucket or similar watertight container. 12.1.2.13 A small scoop. 12.1.2.14 A drying oven, capable of maintaining a temperature of 105 C to 100 C. 12.1.2.15 A stop clock, readable to 1 s. 12.1.2.16 Apparatus for extracting compacted specimens from the mould (optional). 12.1.2.17 A water container of about 5 L capacity. 12.1.3 Calibration of vibrating hammer The vibrating hammer shall be checked and calibrated as specified in 11.7.3. 12.1.4 Preparation of sample 12.1.4.1 Take enough material from the soil prepared as described in of BS 1377-1:2016, 8.6.4, to enable at least two test specimens to be prepared. 12.1.4.2 Sieve the soil on a 6.3 mm test sieve. The retained material may be broken down to sizes between 2 mm and 6.3 mm provided that the total proportion by mass in this size range does not exceed 10%. 12.1.4.3 Mix the soil thoroughly on the large metal tray and divide into at least two representative specimens of about 3 kg each. 12.1.4.4 Pour each prepared specimen into warm water in a bucket or suitable container and stir thoroughly to remove air bubbles. 12.1.4.5 Cover the container and allow to stand for several hours, e.g. overnight, to cool. |
| 44 | 12.1.5 Procedure 12.1.5.1 Measure the internal dimensions of the compaction mould to 0.1 mm. 12.1.5.2 Attach the extension to the mould and place the mould assembly in the watertight container on a solid base, e.g. a concrete floor or plinth. Pour water to about 50 mm depth in the mould body, and to the same level in the surrounding container. 12.1.5.3 Add a specimen of the soil-water mixture to the mould with the scoop, placing it carefully under the water surface without loss of fines and without segregation of coarse particles. The quantity of specimen should be such that the mould is ab… 12.1.5.4 Place the circular tamper on the soil and compact with the vibrating hammer for at least 2 min or until there is no further significant decrease in sample height. During this period apply a steady downward force on the hammer so that the tota… 12.1.5.5 Repeat 12.2.5.3 and 12.2.5.4 twice more, ensuring that the surface of the specimen is always under water. After compaction of the third layer its surface shall be at least level with, but not more than 6 mm proud of, the mould body. 12.1.5.6 Remove the mould containing the soil from the container, clean off any adhering soil from the outside and allow free water to drain from the specimen. 12.1.5.7 Remove the extension carefully and trim off the compacted soil level with the top of the mould, using the straightedge. Refill cavities, left by removal of any coarse particles, with finer material, well pressed in. 12.1.5.8 Extract the compacted soil from the mould into the small weighed metal tray, without loss of any soil particles. 12.1.5.9 Dry the soil in an oven at 105 C to 110 C, weigh when cool and determine the mass of soil, m (in g), to 1 g. 12.1.5.10 Repeat 12.2.5.2 to 12.2.5.9 using the second batch of prepared specimen. 12.1.5.11 If the dry masses from the two tests differ by more than 50 g, repeat the procedure using fresh specimens of the soil. 12.1.6 Calculations and expression of results 12.1.6.1 Calculate the internal volume, V (in cm3), of the mould. 12.1.6.2 Calculate the maximum dry density (pdmax.) of the soil (in Mg/m3) from the formula: |
| 45 | 12.1.7 Test report The test report shall affirm that the test was carried out in accordance with this British Standard, 12.1 and shall contain the following information: 12.2 Maximum density of gravelly soils 12.2.1 Apparatus 12.2.1.1 A cylindrical, corrosion-resistant metal mould, i.e., the CBR mould, as described in 15.2.2.2. 12.2.1.2 A vibrating hammer, as specified in 11.7.2.2. |
| 46 | 12.2.1.3 A steel tamper for attachment to the vibrating hammer, as specified in 11.7.2.3. [See Figure 8(b)]. 12.2.1.4 Supporting guide frame for vibrating hammer (optional). 12.2.1.5 A watertight container, large enough to hold the mould. 12.2.1.6 A balance, readable to 5 g. 12.2.1.7 A straightedge, e.g. a steel strip about 300 mm long, 25 mm wide, and 3 mm thick, with one bevelled edge. 12.2.1.8 Test sieves, of aperture sizes 37.5 mm and 20 mm and a receiver. 12.2.1.9 Two corrosion-resistant, metal or plastics trays, with sides, e.g. about 80 mm deep, of a size suitable for the quantity of material to be used. 12.2.1.10 A bucket, or similar waterproof container. 12.2.1.11 A scoop. 12.2.1.12 A drying oven, capable of maintaining a temperature of 105 C to 110 C. 12.2.1.13 A stopclock, readable to 1 s. 12.2.1.14 Apparatus for extracting compacted specimens from the mould. 12.2.1.15 A water container, of about 10 L capacity. 12.2.2 Calibration of vibrating hammer The vibrating hammer shall be checked and calibrated as specified in 11.7.3. 12.2.3 Preparation of specimen 12.2.3.1 Take enough material from the soil prepared as described in BS 1377-1:2016, 8.6.4, to enable at least two test specimens to be prepared. 12.2.3.2 Sieve the soil on a 37.5 mm test sieve. The retained material may be broken down to sizes between 20 mm and 6.3 mm provided that the total proportion by mass in this size range does not exceed 30%. 12.2.3.3 Mix the soil thoroughly and divide into at least two representative specimens of about 8 kg each. 12.2.3.4 Pour each prepared specimen into warm water into a bucket or suitable container and stir thoroughly to remove air bubbles. 12.2.3.5 Cover the container and allow to stand for several hours, e.g. overnight, to cool. 12.2.4 Procedure 12.2.4.1 Measure the internal dimensions of the mould to 0.5 mm. 12.2.4.2 Attach the extension to the mould and place the mould assembly in the watertight container on a suitable base, e.g. a concrete floor or plinth. Pour water to about 50 mm depth in the mould body, and to the same level in the surrounding contai… 12.2.4.3 Add some of the soil-water mixture to the mould with the scoop, placing it carefully under the water surface without loss of fines and without segregation of coarse particles and continue until the mould is about one-third filled when compact… |
| 47 | 12.2.4.4 Place the circular tamper on the soil and compact with the vibrating hammer. Apply a steady downward force between 300 N and 400 N for at least 3 min or until there is no further significant decrease in sample height. 12.2.4.5 Repeat 12.3.5.3 and 12.3.5.4 twice, each adding a third of the height of the mould after compaction, ensuring the specimen is always under water. After compaction of the third layer its surface shall be at least level with, but not more than… 12.2.4.6 Remove the mould containing the soil from the container, clean off any adhering soil from the outside and allow free water to drain from the specimen. 12.2.4.7 Remove the extension carefully and trim off the compacted soil level with the top of the mould, using the straightedge. Refill cavities left by removal of any coarse particles with finer material, well pressed in. 12.2.4.8 Extract the compacted soil from the mould into a weighed metal tray, without loss of any soil particles. 12.2.4.9 Dry the soil in an oven at 105 C to 110 C, weigh when cool and determine the mass of soil, m (in g), to 5 g. 12.2.4.10 Repeat 12.3.5.2 to 12.3.5.9 using the second batch of prepared specimen. 12.2.4.11 If the dry masses from the two tests differ by more than 150 g, repeat the procedure using fresh specimens of the soil. 12.2.5 Calculations and expression of results 12.2.5.1 Calculate the internal volume, V (in cm3), of the mould. 12.2.5.2 Calculate the maximum dry density of the soil, pdmax. (in Mg/m3), from the formula: 12.2.6 Test report The test report shall affirm that the test was carried out in accordance with this British Standard, 12.2 and shall contain the following information: |
| 48 | 12.3 Minimum density of sands 12.3.2 Apparatus 12.3.2.1 A 1 L glass measuring cylinder, graduated to 20 mL, preferably without a pouring lip. 12.3.2.2 A rubber bung, to fit the cylinder or a piece of rubber membrane and a rubber O-ring or other suitable material to seal its mouth. 12.3.2.3 A balance, readable to 1 g. 12.3.2.4 A drying oven, capable of maintaining a temperature of 105 C to 110 C and in accordance with BS 1377-1:2016, 5.2.2.1. 12.3.2.5 A 2 mm test sieve, and receiver. 12.3.3 Preparation of specimen 12.3.3.1 Prepare the sand in accordance with BS 1377-1:2016, 8.6.4, and pass it through a 2 mm test sieve if necessary. 12.3.3.2 Obtain a representative test specimen of 1 000 ±1 g. 12.3.4 Procedure 12.3.4.1 Place the weighed specimen of sand in the glass cylinder and fit the bung or cover. 12.3.4.2 Shake the cylinder to loosen the sand and invert it a few times. 12.3.4.3 Turn the cylinder upside down, pause until all the sand is at rest, then quickly turn it right way up. Stand the cylinder on a flat surface without jarring it. 12.3.4.4 Record the volume reading (V) at the mean level of the surface of the sand to the nearest 10 mL. Avoid shaking or jolting the cylinder during this operation. 12.3.4.5 Repeat 12.3.4.2, 12.3.4.3 and 12.3.4.4 to give at least 10 readings. 12.3.5 Calculations and expression of results Calculate the minimum dry density of the sand, ρsmin (in Mg/m3), from the formula: |
| 49 | 12.3.6 Test report The test report shall affirm that the test was carried out in accordance with this British Standard, 12.3 and shall contain the following information: 12.4 Minimum density of gravelly soils 12.4.1 General 12.4.2 Apparatus 12.4.2.1 A cylindrical, corrosion-resistant, metal mould, i.e. the CBR mould, as described in 15.2.2.2. 12.4.2.2 A bucket or similar container of suitable size. 12.4.2.3 A corrosion-resistant, metal or plastics tray with sides, about 80 mm deep, of a size suitable for the quantity of material to be used. 12.4.2.4 A suitable container, for weighing the sample. 12.4.2.5 A scoop. 12.4.2.6 A straightedge, e.g. a steel strip about 300 mm long, 25 mm wide, and 3 mm thick. 12.4.2.7 A balance, readable to 5 g. 12.4.2.8 A 37.5 mm test sieve, and a receiver. 12.4.2.9 A drying oven, capable of maintaining a temperature of 105 C to 110 C. 12.4.3 Preparation of specimen 12.4.3.1 Prepare the soil in accordance with BS 1377-1:2016, 8.6.4, and pass through a 37.5 mm test sieve if necessary. 12.4.3.2 Take a representative specimen, obtained by riffling, at least 50% larger than the internal volume of the mould. 12.4.4 Procedure 12.4.4.1 Measure the internal dimensions of the mould to 0.5 mm. 12.4.4.2 Place the specimen in the bucket and mix to ensure an even distribution of particles of all sizes. 12.4.4.3 Place the mould, with base and extension attached, on the tray and pour the contents of the bucket steadily from a height of about 0.5 m into the mould, for about 1 s. 12.4.4.4 Carefully remove the extension and level the surface of the soil to the top of the mould without disturbing the soil in the mould or jarring the mould. Pick off large particles individually by hand, and finally check the surface with the stra… |
| 50 | 12.4.4.5 Empty the contents of the mould into the weighed container and determine the mass of soil, m (g), to the nearest 5 g. 12.4.4.6 Remix the soil with the excess remaining on the tray and repeat 12.4.4.2 to 12.4.4.5 to give at least 10 determinations altogether. 12.4.5 Calculations and expression of results 12.4.5.1 Calculate the internal volume, V (in cm3), of the mould. 12.4.5.2 Calculate the minimum dry density of the soil, ρdmin (in Mg/m3), from the formula: 12.4.6 Test report The test report shall affirm that the test was carried out in accordance with this British Standard, 12.4 and shall contain the following information: 12.5 Derivation of density index 13 Determination of the moisture condition value (MCV) 13.1 General |
| 51 | 13.2 Apparatus 13.2.1 Moisture condition apparatus, complete with mould, separating disc and a means of measuring the penetration or protrusion of the rammer to an accuracy of 0.1 mm. The main features are shown in Figure 9; other forms of apparatus are acceptable p… |
| 53 | 13.2.2 A balance of 2 kg, capacity reading to 1 g. 13.2.3 A 20 mm test sieve, and receiver. 13.2.4 A corrosion-resistant metal or plastics tray with sides, e.g. about 80 mm deep, of a size suitable for the quantity of material to be used. 13.2.5 Apparatus for extracting specimens from the mould (optional). 13.2.6 Apparatus for the determination of water content, as described in BS EN ISO 17892-1. 13.3 Checking the moisture condition apparatus 13.3.1 Before and after a series of tests the apparatus shall be checked and if necessary adjusted as follows: 13.3.1.1 The rammer shall be capable of dropping freely. 13.3.1.2 The height of drop of the rammer shall be set to 250 mm in accordance with the manufacturer’s instructions. 13.3.1.3 All components of the apparatus shall be secure. 13.3.1.4 The separating disc shall be of such a size that it will pass freely through the bore of the mould. Any disc oversize shall be discarded. 13.4 Determination of the MCV of a specimen of soil at its natural water content 13.4.1 Procedure 13.4.1.1 Pass the soil through a 20 mm test sieve, break down particle aggregations as necessary, and remove only individual particles coarser than 20 mm. Weigh the removed material to 1 g if the proportion of coarse particles is to be reported. 13.4.1.2 Take a representative specimen of material passing the 20 mm test sieve for determination of the water content. 13.4.1.3 Take a 1.5 kg ±20 g specimen of soil passing the 20 mm test sieve. The aggregations of soil placed in the mould need not be broken down any further after passing through the 20 mm sieve. Place the soil as loosely as possible in the clean, dry… |
| 54 | 13.4.1.4 With the rammer held in the raised position by the retaining pin, locate the mould on the base of the apparatus, and adjust the automatic counter to zero. 13.4.1.5 Hold the rammer steady and remove the retaining pin. Lower the rammer gently onto the separating disc and allow it to penetrate into the mould under its own weight until it comes to rest. Set the height of drop at 250 ±5 mm (see Note to 13.3…. 13.4.1.6 Apply one blow of the rammer to the specimen by raising the rammer until it is released by the automatic catch. Measure the penetration of the rammer into the mould, or the length of rammer protruding from the mould, to 0.1 mm. 13.4.1.7 Reset the height of drop to 250 mm. 13.4.1.8 Repeat 13.4.1.6 and 13.4.1.7, taking readings of penetration or protrusion after a selected accumulated number of blows (see Figure A.1) and resetting the height of drop to 250 mm as necessary, until no further significant increase in penetra… 13.4.1.9 Carefully raise the rammer and insert the retaining pin. 13.4.1.10 Remove the mould from the apparatus, take off its base and extract the specimen. This specimen shall not be used to determine the water content. 13.4.2 Calculations and expression of results (see Figure A.1) 13.4.2.1 Calculate the change in penetration between any given number of blows, n, and four times as many blows (total 4n; e.g. 1 and 4, 2 and 8, etc.) 13.4.2.2 Plot the change in penetration, on a linear scale, against the initial number of blows, n, on a logarithmic scale. 13.4.2.3 Draw the steepest possible straight line through the points lying immediately before or passing through the 5 mm change in penetration value. The MCV is then defined as 10 log B (to the nearest 0.1) where B is the number of blows at which the… |
| 56 | 13.4.2.4 Express the moisture condition value of the soil at natural water content to the nearest 0.1 for a laboratory test and to the nearest 0.5 for a field test. 13.4.3 Test report The test report shall affirm that the test was carried out in accordance with this British Standard, 13.4 and shall contain the following information: 13.5 Determination of the MCV/water content relation of a soil 13.5.1 Procedure 13.5.1.1 Soils not susceptible to crushing during compaction 13.5.1.1.1 Take a specimen of about 4 kg of the soil which has been allowed to partially air dry. Do not allow the soil to dry completely before the test. 13.5.1.1.2 Pass the soil through a 20 mm test sieve, break down particle aggregations as necessary, and remove only individual particles coarser than 20 mm. Weigh the removed material to 1 g if the proportion of coarse particles is to be reported. 13.5.1.1.3 Take a representative specimen of material passing the 20 mm test sieve for determination of the water content as described in BS EN ISO 17892-1. 13.5.1.1.4 Thoroughly mix the soil passing the 20 mm test sieve with a suitable amount of water. 13.5.1.1.5 Pass the mixed soil through a 20 mm test sieve to break down particle aggregations and take a 1.5 kg ±20 g specimen of the sieved soil. 13.5.1.1.6 Carry out the procedure described in 13.4.1.3 to 13.4.1.9. |
| 57 | 13.5.1.1.7 Remove the mould from the apparatus and take off its base. Extract the specimen from the mould and place it on the tray. Take a representative specimen and determine its water content, w, as described in BS EN ISO 17892-1. 13.5.1.1.8 Break up the remainder of the specimen and mix with the remainder of the original sample. Add a suitable increment of water and mix thoroughly into the specimen. 13.5.1.1.9 Repeat 13.5.1.1.5 to 13.5.1.1.8 for each increment of water added. Make at least four determinations. The range of water contents shall be such that the range of MCVs is approximately 3 to 14. 13.5.1.2 Soils susceptible to crushing during compaction 13.5.1.2.1 Take four or more specimens of about 2.5 kg of air-dried soil. Mix each specimen thoroughly with a different amount of water to give a suitable range of water contents. 13.5.1.2.2 Prepare and test each specimen as described in 13.5.1.1.2, 13.5.1.1.3, 13.5.1.1.6 and 13.5.1.1.7. 13.5.1.2.3 Discard the remainder of each soil specimen. 13.5.2 Calculations and expression of results 13.5.3 Test report 13.6 Rapid assessment of whether a soil is stronger than a precalibrated standard |
| 58 | 13.6.1 Procedure 13.6.1.1 Pass the soil through a 20 mm test sieve, break down particle aggregations as necessary, and remove only individual particles coarser than 20 mm. Weigh the removed material to 1 g. 13.6.1.2 Take a representative specimen of material passing the 20 mm test sieve for determination of the water content as described in BS EN ISO 17892-1. 13.6.1.3 Take a 1.5 kg ±20 g specimen of soil passing the 20 mm test sieve. The aggregations of soil placed in the mould need not be broken down any further after passing through the 20 mm sieve. Place the soil as loosely as possible in the clean, dry… 13.6.1.4 Locate the mould in the recess on the base of the apparatus and adjust the automatic counter to zero. 13.6.1.5 Hold the rammer steady and remove the retaining pin. Lower the rammer gently onto the separating disc and allow it to penetrate into the mould under its own weight until it comes to rest. Set the height of drop at 250 ±5 mm. 13.6.1.6 Apply one blow of the rammer to the specimen by raising the rammer until it is released by the automatic catch. 13.6.1.7 Reset the height of drop to 250 mm. 13.6.1.8 Apply further blows, resetting the height of drop as necessary, until the total number of blows is equal to that of the MCV equivalent to the precalibrated standard. Measure the penetration of the rammer into the mould, or the length of ramme… 13.6.1.9 Apply further blows equal to three times the initial number, without any further adjustment to the height of drop of the rammer. Measure the penetration or protrusion of the rammer as above. 13.6.1.10 Remove the mould from the apparatus, take off its base, and extract the specimen. 13.6.2 Calculations and expression of results Calculate the difference between the initial and final penetration readings. A difference of more than 5.0 mm indicates that the soil is stronger than the precalibrated standard; a difference of less than 5.0 mm indicates that it is weaker. 13.6.3 Test report The test report shall affirm that the test was carried out in accordance with this British Standard, 13.6 and shall contain the following information: |
| 59 | 14 Determination of the chalk crushing value (CCV) 14.1 General 14.2 Apparatus 14.2.1 Moisture condition apparatus complete with accessories, as described in 13.2 and shown in Figure 9. 14.2.2 A balance of 2 kg, capacity readable to 1 g. 14.2.3 A hammer, for example a 2 lb club hammer. 14.2.4 Test sieves, of aperture sizes 20 mm and 10 mm, and receiver. 14.2.5 A metal tray, with sides about 80 mm deep. 14.2.6 Apparatus for extracting specimens from the mould (optional). 14.3 Checking the moisture condition apparatus 14.4 Determination of the chalk crushing value (CCV) 14.4.1 Procedure 14.4.1.1 Take a 1 kg ±20 g specimen of the material passing the 20 mm test sieve and retained on the 10 mm test sieve. Determine the percentage of material retained on the 10 mm test sieve from a specimen of appropriate size. Break up lumps of chalk l… 14.4.1.2 Place the specimen loosely in the clean, dry mould and place the separating disc on top of the chalk. 14.4.1.3 With the rammer held in the raised position by the retaining pin, locate the mould on the base of the apparatus, and adjust the automatic counter to zero. 14.4.1.4 Hold the rammer steady and remove the retaining pin. Lower the rammer gently on to the separating disc and allow it to penetrate into the mould under its own weight until it comes to rest. Set the height of drop at 250 ±5 mm. 14.4.1.5 Apply one blow of the rammer to the specimen by raising the rammer until it is released by the automatic catch. Measure the penetration of the rammer into the mould, or the length of rammer protruding from the mould, to 0.1 mm. |
| 60 | 14.4.1.6 Reset the height of drop to 250 mm. 14.4.1.7 Repeat 14.4.1.5 and 14.4.1.6, taking readings of penetration or protrusion after selected accumulated numbers of blows and resetting the height of drop to 250 mm as necessary. 14.4.1.8 The test shall be deemed to be complete when water starts to ooze from the base of the mould, or no further penetration occurs, or a maximum of 50 blows is reached. 14.4.1.9 Carefully raise the rammer and insert the retaining pin. 14.4.1.10 Remove the mould from the apparatus, take off the base and extract the crushed chalk. 14.4.2 Calculations and expression of results (see Figure A.2) 14.4.2.1 Plot the penetration or protrusion of the rammer (in mm) on a linear scale against the number of blows on a logarithmic scale. 14.4.2.2 The greater part of the relation should form a straight line, the slope of which represents the rate at which the chalk was crushed. The chalk crushing value (CCV) is taken as one-tenth of the slope of the straight line. 14.4.3 Test report The test report shall affirm that the test was carried out in accordance with this British Standard, 14.4 and shall contain the following information: 15 Determination of the California Bearing Ratio (CBR) |
| 61 | 15.1 General 15.1.1 Limitations. Because of the size of the sample and of the plunger, the materials to test shall have a maximum particle size not exceeding 20 mm. (See 15.2.1.1.) 15.1.2 Test conditions. The following test conditions shall be specified before a test is started: 15.2 Preparation of test specimen 15.2.1 General |
| 62 | 15.2.1.1 Material. The CBR test shall be carried out on material passing the 20 mm test sieve prepared as described in BS 1377-1:2016, 8.6.5. If the soil contains particles larger than this the fraction retained on the 20 mm test sieve shall be remove… 15.2.1.2 Initial preparation. The initial soil sample for testing shall be obtained as described in BS 1377-1:2016, 8.6.1 and 8.6.5. After bringing it to the required water content the soil shall be thoroughly mixed and shall normally be sealed and st… 15.2.1.3 Mass of soil for test 15.2.1.3.1 When the density or air voids content of a compacted specimen is specified, the exact amount of soil required for the test can be calculated as described in 15.2.1.3.2 or 15.2.1.3.3. When a compactive effort is specified, the mass of soil c… 15.2.1.3.3 Air voids specification. The dry density, ρd (in Mg/m3), corresponding to an air voids content of Va (%) is given by the formula: |
| 63 | 15.2.1.3.4 Compactive effort specification. About 6 kg of soil shall be prepared for each specimen to be tested. The initial mass shall be measured to the nearest 5 g so that the mass used for the test specimen can be determined after compaction by di… 15.2.2 Apparatus 15.2.2.1 Test sieves, of aperture sizes 20 mm and 5 mm. 15.2.2.2 A cylindrical, corrosion-resistant, metal mould, i.e. the CBR mould, having a nominal internal diameter of 152 ±0.5 mm. The mould shall be fitted with a detachable baseplate and a removable extension. The essential dimensions are shown in Fig… |
| 64 | 15.2.2.3 A compression device for static compaction, [for methods (1) and (2)]. Horizontal platens shall be large enough to cover a 150 mm diameter circle and capable of a separation of not less than 300 mm. The device shall be capable of applying a f… 15.2.2.4 Metal plugs, 150 ±0.5 mm in diameter and 50 ±1.0 mm thick, for static compaction of a soil specimen [for methods (1) and (2)]. A handle which may be screwed into the plugs facilitates removal after compaction. The essential dimensions are sho… 15.2.2.5 A metal rammer, [for methods (3) and (5)]. These shall be either the 2.5 kg rammer as specified in 11.3.2, or the 4.5 kg rammer as specified in 11.5.2, depending on the degree of compaction required. A mechanical compacting apparatus may be u… 15.2.2.6 An electric, vibrating hammer and tamper, as specified in 11.7.2.2 and 11.7.2.3 [for methods (4) and (6)]. 15.2.2.7 A steel rod, about 16 mm in diameter and 600 mm long. 15.2.2.8 A steel straightedge, e.g. a steel strip about 300 mm long, 25 mm wide and 3 mm thick, with one bevelled edge. 15.2.2.9 A spatula. 15.2.2.10 A balance, capable of weighing up to 25 kg readable to 5 g. 15.2.2.11 Apparatus for water content determination, as described in BS EN ISO 17892-1. 15.2.2.12 Filter papers, 150 mm in diameter, e.g. Whatman No. 1 or equivalent. 15.2.3 Specimen preparation by static compression 15.2.3.1 General Static compression shall be carried out by one of the methods described in 15.2.3.2 and 15.2.3.3 [methods (1) and (2) respectively]. Initial preparation of the mould shall be as described in 15.2.3.1.1 to 15.2.3.1.4. 15.2.3.1.1 Weigh the mould with baseplate attached to the nearest 5 g (m2). 15.2.3.1.2 Measure the internal dimensions to 0.5 mm. 15.2.3.1.3 Attach the extension collar to the mould and cover the baseplate with a filter paper. 15.2.3.1.4 Measure the depth of the collar as fitted, and the thickness of the spacer plug or plugs, to 0.1 mm. 15.2.3.2 Method (1). Compression with tamping 15.2.3.2.1 Pour the weighed soil slowly into the mould while tamping it with the steel rod. Avoid segregation of particle sizes and ensure that the largest particles are uniformly distributed within the mould. 15.2.3.2.2 When all the soil is added, level off its surface which should then be about 5 mm to 10 mm above the top of the mould body if the correct amount of tamping has been applied. 15.2.3.2.3 Place a filter paper on the soil surface, followed by the 50 mm thick spacer plug. 15.2.3.2.4 Place the mould assembly in the compression device and apply a load to the sample until the top of the plug is flush with the collar. Hold the load constant for at least 30 s. 15.2.3.2.5 Release the load. If rebound occurs reapply the load for a longer period. 15.2.3.2.6 Remove the spacer plug, filter paper and collar. |
| 65 | 15.2.3.2.7 Weigh the mould, soil and baseplate to the nearest 5 g (m3). 15.2.3.2.8 Unless the specimen is to be tested immediately, seal the specimen (by screwing on the top plate if appropriate) to prevent loss of water. With clay soils, or soils in which the air content is less than 5%, allow the specimen to stand for a… 15.2.3.3 Method (2). Compression in layers 15.2.3.3.1 Divide the prepared quantity of soil into three portions equal to within 50 g and seal each portion in an airtight container until required for use, to prevent loss of water. 15.2.3.3.2 Place one portion of soil in the mould and level the surface. 15.2.3.3.3 Place the three spacer plugs on top of the soil and compress the soil using the compression device until the thickness of the soil, after removal of the load, is about one-third of the depth of the mould. 15.2.3.3.4 Repeat 15.2.3.3.2 and 15.2.3.3.3 using two plugs and then one plug. During the last operation compress the soil until the top surface of the plug is level with the top of the collar. 15.2.3.3.5 Weigh the mould, soil and baseplate to the nearest 5 g (m3). 15.2.3.3.6 Seal and store the sample as described in 15.2.3.2.8. 15.2.4 Specimen preparation by dynamic compaction 15.2.4.1 General Dynamic compaction shall be carried out by one of the methods described in 15.2.4.2 to 15.2.4.5 [methods (3) to (6) respectively]. 15.2.4.2 Method (3). Rammer compaction to a specified density 15.2.4.2.1 Divide the prepared quantity of soil into five portions equal to within 50 g and seal each portion in an airtight container until required for use, to prevent loss of water. 15.2.4.2.2 Stand the mould assembly on a solid base, e.g. a concrete floor or plinth. 15.2.4.2.3 Place the first portion of soil into the mould and compact it using either the 2.5 kg rammer or the 4.5 kg rammer, until the layer occupies about one-fifth of the height of the mould. Ensure that the blows are evenly distributed over the su… 15.2.4.2.4 Repeat 15.2.4.2.3 using the other four portions of soil in turn, so that the final level of the fifth layer is just above the top of the mould. 15.2.4.2.5 Remove the collar and trim the soil flush with the top of the mould with the scraper, checking with the steel straightedge. 15.2.4.2.6 Weigh the mould, soil and baseplate to the nearest 5 g (m3). 15.2.4.2.7 Seal and store the specimen as described in 15.2.3.2.8. 15.2.4.3 Method (4). Vibrating compaction to a specified density (suitable for coarse soils) 15.2.4.3.1 Divide the prepared quantity of soil into three portions equal to within 50 g and seal each portion in an airtight container until required for use, to prevent loss of water. |
| 66 | 15.2.4.3.2 Stand the mould assembly on a solid base, e.g. a concrete floor or plinth. 15.2.4.3.3 Place the first portion of soil into the mould and compact it using the vibrating hammer as described in 11.7.5.1.4. Continue the compaction until the thickness of the layer is about one-third of the height of the mould. 15.2.4.3.4 Repeat 15.2.4.3.3 using the other two portions of soil in turn, so that the final level of the third layer is just above the top of the mould. (See note to 15.2.4.2.4). 15.2.4.3.5 Remove the collar and trim the soil flush with the top of the mould with the scraper, checking with the steel straightedge. 15.2.4.3.6 Weigh the mould, soil and baseplate to the nearest 5 g (m3). 15.2.4.3.7 Seal and store the specimen as in 15.2.3.2.8. 15.2.4.4 Method (5). Rammer compaction with specified effort 15.2.4.4.1 The specified effort of compaction shall correspond to the 2.5 kg rammer method (see 11.4) or to the 4.5 kg rammer method (see 11.6) or to an intermediate value (see Note). When the 2.5 kg rammer method is used the procedure is as described… 15.2.4.4.2 Divide the prepared quantity of soil into three (five*) portions equal to within 50 g and seal each portion in an airtight container until required for use, to prevent loss of water. 15.2.4.4.3 Stand the mould assembly on a solid base, e.g. a concrete floor or plinth. 15.2.4.4.4 Place the first portion of soil into the mould and compact it, so that after 62 blows of the appropriate rammer the layer occupies about or a little more than one-third (one-fifth*) of the height of the mould. Ensure that the blows are even… 15.2.4.4.5 Repeat 15.2.4.4.4 using the other two (four*) portions of soil in turn, so that the final level of the soil surface is not more than 6 mm above the top of the mould body. |
| 67 | 15.2.4.4.6 Remove the collar and trim the soil flush with the top of the mould with the scraper, checking with the steel straightedge. 15.2.4.4.7 Weigh the mould, soil and baseplate to the nearest 5 g (m3). 15.2.4.4.8 Seal and store the specimen as described in 15.2.3.2.8. 15.2.4.5 Method (6). Vibrating compaction with specified effort (suitable for coarse soils) 15.2.4.5.1 Divide the prepared quantity of soil into three portions equal to within 50 g and seal each portion in an airtight container until required for use, to prevent loss of water. 15.2.4.5.2 Stand the mould assembly on a solid base, e.g. a concrete floor or plinth. 15.2.4.5.3 Place the first portion of soil into the mould and compact it using the vibrating hammer fitted with the circular steel tamper. Compact for a period of 60 ±2 s, applying a total downward force on the sample of between 300 N and 400 N (see 1… 15.2.4.5.4 Repeat 15.2.4.5.3 using the other two portions of soil in turn, so that the final level of the soil surface is not more than 6 mm above the top of the mould. (See Note to 15.2.4.4.5.) 15.2.4.5.5 Remove the collar and trim the soil flush with the top of the mould with the scraper, checking with the steel straightedge. 15.2.4.5.6 Weigh the mould, soil and baseplate to the nearest 5 g (m3). 15.2.4.5.7 Seal and store the specimen as described in 15.2.3.2.8. 15.2.5 Preparation of undisturbed specimen 15.3 Soaking 15.3.1 General If soaking is specified it shall be carried out as described in 15.3.3.1 to 15.3.3.13. 15.3.2 Apparatus 15.3.2.1 A perforated baseplate, fitted to the CBR mould in place of the normal baseplate (see Figure 13). 15.3.2.2 A perforated swell plate, with an adjustable stem to provide a seating for the stem of a deformation indicator. (See Figure 15). 15.3.2.3 Tripod, mounting to support the deformation indicator. A suitable assembly is shown in Figure 15. |
| 69 | 15.3.2.4 A deformation indicator, having a travel of 25 mm and reading to 0.01 mm. 15.3.2.5 A soaking tank, large enough to allow the CBR mould with baseplate to be submerged, preferably supported on an open mesh platform. 15.3.2.6 Annular surcharge discs, each having a mass known to ±50 g, an internal diameter of 52 mm to 54 mm and an external diameter of 145 mm to 150 mm. Alternatively, half-circular segments may be used. 15.3.2.7 Silicone grease or petroleum jelly. 15.3.3 Soaking procedure 15.3.3.1 Remove the baseplate from the mould and replace it with the perforated baseplate. 15.3.3.2 Fit the collar to the other end of the mould, packing the screw threads with silicone grease or petroleum jelly to obtain a watertight joint. 15.3.3.3 Place the mould assembly in the empty soaking tank. Place a filter paper on top of the specimen, followed by the perforated swell plate. Fit the required number of annular surcharge discs around the stem on the perforated plate. 15.3.3.4 Mount the deformation indicator support on top of the extension collar, secure the deformation indicator in place and adjust the stem on the perforated plate to give a convenient zero reading. (See Figure 15.) 15.3.3.5 Fill the immersion tank with water to just below the top of the mould extension collar. Start the timer when the water has just covered the baseplate. 15.3.3.6 Record readings of the deformation indicator at suitable intervals of time, depending on the rate of movement. 15.3.3.7 Record the time taken for water to appear at the top of the specimen. (This might not necessarily indicate the end of the swelling stage.) If this has not occurred within 3 days, flood the top of the specimen and leave to soak for a further d… 15.3.3.8 Plot a graph of swelling (as indicated by the deformation indicator movement) against elapsed time or square-root time. Flattening of the curve indicates when swelling is substantially complete. 15.3.3.9 Take off the deformation indicator and its support, remove the mould assembly from the immersion tank and allow the specimen to drain for 15 min. If the tank is fitted with a mesh platform leave the mould there to drain after emptying the tank. 15.3.3.10 Remove the surcharge discs, perforated plate and extension collar. Remove the perforated baseplate and refit the original baseplate. |
| 70 | 15.3.3.11 Weigh the specimen with mould and baseplate to the nearest 5 g if the density after soaking is required. 15.3.3.12 If the specimen has swollen, trim it level with the end of the mould and reweigh. 15.3.3.13 The specimen is then ready for test in the soaked condition. 15.4 Penetration test procedure |
| 71 | 15.4.1 Apparatus 15.4.1.1 A cylindrical metal plunger, the lower end of which shall be of hardened steel and have a nominal cross-sectional area of 1 935 mm2, corresponding to a specified diameter of 49.65 ±0.10 mm. A cylindrical metal plunger approximately 250 mm lon… |
| 72 | 15.4.1.2 A machine for applying the test force through the plunger, having a means for applying the force at a controlled rate. The machine shall be capable of applying at least 45 kN. The unloaded machine approach speed shall be 1.2 ±0.2 mm/min. 15.4.1.3 A calibrated force-measuring device, complying with BS 1377-1:2016, 5.2.1.6. The device shall be supported by the crosshead of the compression machine so as to prevent its own weight being transferred to the test specimen. 15.4.1.4 A means of measuring the penetration of the plunger into the specimen, to within 0.01 mm, such as a deformation indicator or a digital micrometer. The measuring device shall have a travel of at least 20 mm, reading to 0.01 mm or better and f… 15.4.1.5 A stopclock or stopwatch, readable to 1 s. 15.4.1.6 The CBR mould, as described in 15.2.2.2. 15.4.1.7 Surcharge discs, as described in 15.3.2.6. 15.4.2 Procedure 15.4.2.1 Place the mould with baseplate containing the specimen, with the top face of the specimen exposed, centrally on the lower plate of the testing machine. 15.4.2.2 Place the appropriate annular surcharge discs on top of the specimen. 15.4.2.3 Fit into place the cylindrical plunger and force-measuring device assembly with the face of the plunger resting on the surface of the specimen. 15.4.2.4 Apply a seating force to the plunger, depending on the expected CBR value, as follows. 15.4.2.5 Secure the penetration deformation indicator in position. Record its initial zero reading or reset it to read zero. 15.4.2.6 Start the test so that the plunger penetrates the specimen at a nominal rate of 1 mm/min, and at the same instant start the timer. 15.4.2.7 Record readings of the force gauge at intervals of penetration of 0.25 mm, to a total penetration not exceeding 7.5 mm. |
| 73 | 15.4.2.8 If no further test is to be made on the specimen, proceed to 15.4.3.13. 15.4.2.9 If a test is to be carried out on both ends of the specimen, raise the plunger and level the surface of the specimen by filling in the depression left by the plunger and cutting away any projecting material. Check for flatness with the straig… 15.4.2.10 Remove the baseplate from the lower end of the mould, fit it securely on the top end and invert the mould. Trim the exposed surface if necessary. 15.4.2.11 If the specimen is to be soaked before carrying out a test on the base, follow the procedure described in 15.3.3 and then proceed to 15.4.2.12. 15.4.2.12 Carry out the test on the base by repeating 15.4.2.1 to 15.4.2.8. 15.4.2.13 After completing the penetration test or tests, determine the water content of the test specimen as follows. 15.5 Calculation and plotting 15.5.1 Force-penetration curve 15.5.1.1 Calculate the force applied to the plunger from each reading of the force-measuring device observed during the penetration test. 15.5.1.2 Plot each value of force as ordinate against the corresponding penetration as abscissa and draw a smooth curve through the points. |
| 74 | 15.5.2 Calculation of California Bearing Ratio |
| 76 | 15.5.3 Density calculations 15.5.3.1 Calculate the internal volume of the mould, Vm (in cm3). 15.5.3.2 Bulk density. The initial bulk density, ρ (in Mg/m3), of a specimen compacted with a specified effort [preparation methods (5) and (6); see 15.2.4.4 and 15.2.4.5], or of an undisturbed specimen, is calculated from the formula: 15.5.3.3 Dry density. The initial dry density, ρd (in Mg/m3), of the sample is calculated from the formula: 15.6 Test report |
| 78 | 16 Determination of the one-dimensional consolidation properties 16.1 Test method The test shall be carried out in accordance with BS EN ISO 17892-5:2017. 16.2 Test results The tests results shall include both mandatory and optional reporting in accordance with BS EN ISO 17892-5:2017, 8.1 and 8.2, together with the following additional parameters calculated for each load increment in accordance with BS EN ISO 17892-5:201… 17 Determination of swelling and collapse characteristics |
| 79 | 17.1 General 17.2 Apparatus 17.2.1 The apparatus required for these tests, and its calibration, is specified in BS EN ISO 17892-5. In addition the following are required. 17.2.1.2 For the measurement of swelling, a flanged disc of corrosion-resistant metal with flat and parallel faces, of a diameter about 1 mm less than the diameter of the consolidation ring. The upstand above the flange shall be such as to displace a… 17.2.1.3 For measurement of settlement on saturation, damp cloth and waterproof plastic film, for protecting the specimen from drying out. See 17.5. 17.3 Measurement of swelling pressure 17.3.1 Preparation of specimen. Prepare the test specimen in the consolidation ring by one of the methods described in BS EN ISO 17892-5:2017, 6.2 and weigh the soil and ring as described in BS EN ISO 17892-5:2017, 6.3. If this test is to be followed … 17.3.2 Preparation and assembly of apparatus. The procedure shall be generally as described in BS EN ISO 17892-5. Prepare the porous plates as described in BS EN ISO 17892-5:2017, 5.2 depending on the type of soil. 17.3.3 Test procedure 17.3.3.1 When the specimen is in equilibrium under the small seating load and the deformation gauge has been set and its reading recorded, add water to fill the consolidation cell. At the same instant start the timer. 17.3.3.2 Observe the deformation gauge and, when it indicates that swelling occurs, add weights to the beam hanger to maintain the gauge reading within 0.01 mm of the corrected zero reading. Record the magnitude of each weight added and the correspon… 17.3.3.3 The corrected zero reading is the initial gauge reading adjusted by the correction necessary to allow for deformation of the apparatus due to the present load on the beam hanger. Obtain the correction from the calibration curve derived in BS … 17.3.3.4 Continue to adjust the hanger weight until equilibrium is established with a deformation gauge reading within ±0.01 mm of the relevant corrected zero reading. This procedure could take several hours or days in some cases, and the approach of … |
| 80 | 17.3.3.5 When equilibrium is established, calculate the pressure, σs (in kPa), applied to the specimen from the weights on the beam hanger (including the initial seating load). 17.3.3.6 Then either increase the pressure to the next convenient pressure in the required sequence for a consolidation test as described in BS EN ISO 17892-5:2017, 6.5, or reduce the pressure to a convenient value for a swelling test as described in … 17.3.4 Reporting result. When equilibrium is established report the pressure on the specimen to two significant figures as the swelling pressure. 17.4 Measurement of swelling 17.4.1 Preparation of specimen 17.4.1.1 Prepare the test specimen in the consolidation ring by one of the methods described in BS EN ISO 17892-5:2017, 6.2. The following additional procedure is required. 17.4.1.2 Determine the thickness of the upstand of the flanged disc to 0.01 mm. 17.4.1.3 Place the flanged disc on the flat, glass plate and place the prepared specimen in the consolidation ring, cutting edge downwards, centrally over the disc, with a disc of filter paper interposed. 17.4.1.4 Push the ring steadily downwards without tilting until the cutting edge is firmly in contact with the flange of the disc. 17.4.1.5 Cut off the extruded portion of soil and trim the specimen flat and flush with the upper end of the ring. Remove the flanged disc and filter paper. 17.4.1.6 Weigh the specimen in its ring on the watch glass or tray and determine the mass of the specimen to 0.1 g. 17.4.1.7 From the thickness of the disc and the measured thickness of the ring calculate the specimen height, H0, in mm. 17.4.2 Preparation and assembly of apparatus 17.4.2.1 The procedure shall be as described in BS EN 17892-5:2017, 6.4, but the porous plates shall be air dried after saturation. 17.4.2.2 Mount the ring containing the specimen with the displaced face uppermost and fit the top porous plate centrally inside the ring. Make the necessary adjustments to bring the beam of the loading apparatus to a horizontal position. 17.4.2.3 Secure the deformation gauge in position to allow for measurement of swelling over a range at least equal to the thickness of specimen displaced. 17.4.2.4 Do not add water to the cell at this stage. 17.4.3 Test procedure 17.4.3.1 Determine the swelling pressure, as described in 17.3.3.1 to 17.3.3.5. 17.4.3.2 Record the compression gauge reading. Do not reset it to zero. 17.4.3.3 Reduce the pressure on the specimen to a suitable value by removing weights from the beam hanger. |
| 81 | 17.4.3.4 Record readings of the deformation gauge and plot the readings so that the completion of swelling can be identified. Record the final reading of the compression gauge. 17.4.3.5 Repeat 17.4.3.3 and 17.4.3.4 for further stages of the sequence of unloading down to the selected minimum pressure. The total height of the specimen shall not be allowed to exceed the height of the ring. 17.4.3.6 Reload the specimen back to the swelling pressure, following the same sequence of pressures in reverse. 17.4.3.7 If required, further loading stages may be applied following the procedure described in BS EN ISO 17892-5:2017, 6.5.2. 17.4.3.8 Drain water from the cell and make final measurements as described in BS EN ISO 17892-5:2017, 6.6. 17.4.4 Calculation and plotting 17.4.5 Reporting results 17.5 Measurement of settlement on saturation 17.5.1 Preparation of specimen Prepare the test specimen in the consolidation ring by one of the methods described in BS EN ISO 17892-5:2017, 6.2 and weigh the soil and ring as described in BS EN ISO 17892-5:2017, 6.3. 17.5.2 Preparation and assembly of apparatus The procedure shall be as described in BS EN ISO 17892-5:2017, 6.4 but the porous plates shall be air dried after saturation. 17.5.3 Test procedure 17.5.3.1 Cover the consolidation cell to prevent the specimen drying out, for example by using damp cloth under plastic film. 17.5.3.2 Apply a suitable sequence of pressure to the specimen as described in BS EN ISO 17892-5, 6.5 but omitting 6.5.2.3, up to the specified pressure. 17.5.3.3 When equilibrium is established under the selected load, fill the cell with water so that the specimen is completely submerged, and start the timer. 17.5.3.4 Record readings of the compression gauge at suitable intervals of time while the pressure on the specimen remains constant, until equilibrium is re-established. 17.5.3.5 Carry out further loading and unloading stages as described in BS EN ISO 17892-5:2017, 6.5 as required, with the specimen remaining saturated. Dismantle as described in BS EN ISO 17892-5:2017, 6.6. 17.5.4 Calculation and plotting The calculations and graphical plots shall be as described in BS EN ISO 17892-5, Clause 7. On the plot of compression or void ratio against log pressure the decrease in height of the specimen due to saturation shall be indicated by a vertical line at … |
| 82 | 17.5.5 Reporting results Test data as listed in 16.2 shall be reported as appropriate. 18 Determination of dispersibility 18.1 Pinhole method 18.1.1 General 18.1.2 Apparatus 18.1.2.1 Pinhole test apparatus, as shown in Figure 19(a), consisting essentially of the following. |
| 83 | 18.1.2.2 A standpipe tube of glass, or transparent plastics, of about 3 mm internal diameter and about 1 200 mm long. 18.1.2.3 A scale for the standpipe tube marked in millimetres. 18.1.2.4 A hypodermic needle, or similar, about 100 mm long, with an external diameter of 1.00 mm ±0.1 mm. 18.1.2.5 A burette stand for supporting the pinhole apparatus, standpipe and scale. 18.1.2.6 Graduated glass measuring cylinders, 10 mL, 25 mL, 50 mL (at least two of each). 18.1.2.7 A stopclock, or timer, readable to 1 s. |
| 85 | 18.1.3 Specimen preparation and assembly 18.1.3.1 Do not allow the specimen to dry before testing. 18.1.3.2 Take a specimen of about 150 g of the soil to be tested, at its natural water content. Take a second similar specimen for the determination of the liquid limit and plastic limit, to be carried out as described in BS EN ISO 17892-12. 18.1.3.3 Remove any particles retained on a 2 mm test sieve from the test sample. 18.1.3.4 Increase or decrease the water content to bring the sample to about its plastic limit. Use the thread-rolling procedure described in BS EN ISO 17892-12 as an indication of the required consistency. 18.1.3.5 Determine the resulting water content of the specimen as described in BS EN ISO 17892-1. 18.1.3.6 Fit the outlet end plate to the body of the pinhole apparatus, making a watertight joint. 18.1.3.7 Support the body of the apparatus vertically and place pea gravel to a depth of approximately 50 mm in the bottom of the apparatus, taking care not to block the outlet hole. Level the surface of the gravel and place two discs of wire mesh on … 18.1.3.8 Compact the test specimen into the apparatus in five equal layers, to give a total sample depth of 38 ±2 mm. Apply an equal compactive effort to each layer such that the resulting dry density of the sample is about 95% of the dry density corr… 18.1.3.9 Level the surface of the specimen and push the nipple into the soil at the centre, using finger pressure, until the upper face is flush with the specimen surface. 18.1.3.10 Insert the needle through the nipple and through the compacted specimen to form a continuous hole and then remove the needle. 18.1.3.11 Place a disc of wire mesh over the specimen followed by pea gravel to the top of the body of the apparatus. 18.1.3.12 Fit the top plate to the body, making a watertight joint. 18.1.3.13 Support the apparatus in the burette stand with its cylindrical axis horizontal. 18.1.3.14 Set the constant-head reservoir of the distilled water supply so that the water level can be maintained at a height of 50 ±5 mm above the centre-line of the apparatus. Close the inlet valve. 18.1.4 Test procedure 18.1.4.1 Open the inlet valve to allow water from the reservoir to enter the apparatus and to flow through the specimen until a steady rate of flow is obtained with H = 50 ±5 mm [see Figure 19(a)]. If there is no flow, disconnect the apparatus, reform… |
| 86 | 18.1.4.2 Within 5 min measure the rate of flow, q (in mL/s), by observing the time required to fill the 10 mL measuring cylinder. 18.1.4.3 Observe and record the appearance, including colour, of the water collected in the measuring cylinder. If it is clear, record that fact. 18.1.4.4 Observe and record the clarity and colour of the collected water by looking through the side of the cylinder against a sheet of white paper, and vertically through the water. If individual particles are discernible, record that fact, together… 18.1.4.5 If the collected water is substantially clear after running for about 5 min, continue at 18.1.4.8. 18.1.4.6 If the water is not substantially clear and the rate of flow has increased to between 1.0 and 1.4 mL/s the test is complete. Proceed to 18.1.4.16. 18.1.4.7 If the rate of flow in 18.1.4.6 is less than 1.0 mL/s, continue the test for a further 5 min. If the water is then clear or is only slightly turbid, and the rate of flow is between 0.4 mL/s and 0.8 mL/s, continue at 18.1.4.8. If the water is … 18.1.4.8 Increase the head of water, H, to 180 ±5 mm, and allow the flow to continue for 5 min. Repeat 18.1.4.3 and 18.1.4.4. 18.1.4.9 If the collected water continues to be clear, or has only a slight trace of turbidity, and the rate of flow is between 0.8 mL/s and 1.4 mL/s, record the fact and proceed to 18.1.4.11. 18.1.4.10 If the water is not clear and the rate of flow increases to about the limiting value (see Note 3 to 18.1.4.6), stop the test. Proceed to 18.1.4.16. 18.1.4.11 Increase the head of water, H, to 380 ±5 mm, and allow the flow to continue for 5 min. Repeat 18.1.4.3 and 18.1.4.4. |
| 87 | 18.1.4.12 If the water continues to be clear, or has only a slight trace of turbidity, and the rate of flow is between 1.0 mL/s and 1.8 mL/s, record the fact and continue at 18.1.4.14. 18.1.4.13 If the water is not clear, or the rate of flow has increased to between 1.4 mL/s and 2.7 mL/s (see note 3 to 18.1.4.6), stop the test. Proceed to 18.1.4.16. 18.1.4.14 Increase the head of water, H, to 1 020 ±5 mm and allow the flow to continue for 5 min. Repeat 18.1.4.3 and 18.1.4.4. 18.1.4.15 Observe and record the rate of flow and whether the collected water continues to be clear, or the extent of turbidity, then stop the test. 18.1.4.16 When the flow tests are completed disconnect the distilled water supply, dismantle the apparatus and remove the specimen intact from the body of the apparatus. 18.1.4.17 Cut the sample in half through its axis. 18.1.4.18 Examine the hole and estimate its diameter, d (in mm), by comparison with the needle, or measure its diameter to 0.5 mm using a steel rule. Sketch the configuration of the hole, with measurements, if it is not of uniform diameter. (18.1.4.3 … |
| 88 | 18.1.5 Analysis of test data |
| 89 | 18.1.6 Reporting results The test report shall affirm that the test was carried out in accordance with this British Standard, 18.1, and shall contain the following information, in addition to the relevant information listed in BS 1377-1:2016, Clause 10: 18.2 Crumb method |
| 90 | 18.2.1 Apparatus and reagent 18.2.1.1 A 100 mL glass beaker. 18.2.1.2 A 0.001 M solution of sodium hydroxide (1 milli-equivalent per litre). 18.2.2 Procedure 18.2.2.1 Prepare a few crumbs, each about 6 mm to 10 mm diameter, from representative portions of the soil at the natural water content. 18.2.2.2 Drop the crumbs into a beaker about one-third full of the sodium hydroxide solution. 18.2.2.3 Observe the reaction after allowing to stand for 5 min to 10 min. 18.2.3 Observations Observe the behaviour of the crumbs in accordance with the following guidelines. 18.2.4 Test report The test report shall affirm that the test was carried out in accordance with this British Standard, 18.2, and shall contain the following information, in addition to the relevant information listed in BS 1377-1:2016, Clause 10: 18.3 Dispersion method |
| 91 | 18.3.1 Apparatus The apparatus shall be the same as specified in BS EN ISO 17892-4:2016, 4.3, except that four 100 mL glass measuring cylinders are required; and in addition, the following: 18.3.1.1 Sodium hexametaphosphate solution, as specified in BS EN ISO 17892-4:2016, 4.5.3. 18.3.1.2 Apparatus shall be calibrated as specified in BS EN ISO 17892-4:2016, Annex A. 18.3.2 Sample preparation Prepare two test specimens of equal mass from the fraction of the undried soil passing the 2 mm sieve, as described in BS 1377-1:2016, 8.3 and 8.4.5. The dry mass of soil required depends upon the type of soil. For a sandy soil about 100 g is required, for a silt soil about 50 g, and for clay soil about 30 g is required. 18.3.3 Test procedure 18.3.3.1 Specimen A The procedure shall be as follows. |
| 92 | 18.3.3.2 Specimen B Carry out the test in accordance with BS EN ISO 17892-4:2016, 5.3.3. 18.3.4 Calculations and plotting 18.3.4.1 Calculate the particle sizes and percentages in accordance with BS EN ISO 17892-4:2016, 6.2. (The value of R0 relates to the hydrometer reading in distilled water for specimen A, and in the dispersant solution for specimen B). 18.3.4.2 Draw the resulting particle size distribution curves on a semi-logarithmic chart. 18.3.4.3 Calculate the percentage dispersion, equal to: 18.3.5 Test report The test report shall affirm that the test was carried out in accordance with this British Standard, 18.3, and shall contain the following information, in addition to the relevant information listed in BS 1377-1:2016, Clause 10: |
| 93 | 19 Determination of frost heave 19.1 General 19.2 Preparation of test specimens 19.2.1 Preparation of soil for test on compacted soil The minimum mass of soil required for the complete test is the sum of the following. The mass of each portion will depend on the type of soil. 19.2.2 Preparation of specimens of compacted soil Prepare test specimens in accordance with BS 812-124:2009, Clause 9. 19.2.3 Preparation of undisturbed specimens Prepare test specimens of undisturbed soil from undisturbed samples taken in sampling tubes or as block samples. Preparation of undisturbed specimens shall be in accordance with BS 1377-1:2016, 9.3 or 9.5. 19.3 Test procedure |
| 94 | 20 Determination of consolidation properties using a hydraulic cell 20.1 General Figure 22 – Drainage and loading conditions for consolidation tests in hydraulic cells |
| 96 | 20.1.1 Test conditions The following test conditions shall be specified before starting a test: 20.1.2 Environmental requirements and safety 20.1.2.1 Temperature These tests shall be carried out in a test location in which the temperature is maintained within ±2 C, in accordance with BS 1377-1:2016, 7.1. All apparatus shall be protected from direct sunlight, from local sources of heat and from draughts. 20.1.2.2 Hazard warning |
| 97 | 20.2 Apparatus 20.2.1 Hydraulic consolidation cell and accessories 20.2.1.1 General requirements for the cell 20.2.1.1.1 All metal body components shall be impervious and corrosion resistant. The cell body, top and base shall all be of the same material to minimize the possible effects of electrolytic corrosion. 20.2.1.1.2 The cell when assembled shall be capable of withstanding sustained internal water pressures of up to 1 000 kPa without significant leakage or distortion. 20.2.1.2 Components of the cell 20.2.1.2.1 Cell body, the inside face of which shall be smooth and free from pitting. |
| 100 | 20.2.1.2.2 Top cover, fitted with an air bleed plug and a bushing or seal for a hollow rod (the drainage stem) which is attached to an impermeable flexible diaphragm, e.g. of butyl rubber. Since the drainage stem permits drainage to take place from th… 20.2.1.2.3 The diaphragm, selected from a range of diaphragms of various stiffnesses so that it is appropriate to the soil type and the type of test. 20.2.1.2.4 Cell base, incorporating a central recess for a porous insert (the pore pressure measurement point) connected to a valve on the periphery. 20.2.1.2.5 Connection ports incorporated into the top cover and cell base, as shown in Figure 23. Each port shall be fitted with either a valve, or a blanking plug if it is not required for the test. The ports shall be connected as follows (the corres… 20.2.1.2.6 Porous discs, for the drainage and pore pressure measuring points. Their permeability shall be substantially greater than that of the soil, and they shall withstand the maximum vertical pressure likely to be imposed. The discs shall be chec… 20.2.1.2.7 On-off valves, capable of withstanding the maximum working pressure without leakage. They shall produce negligible volume displacement during operation. 20.2.1.2.8 Flexible porous disc, to act as a drainage layer through which water from the specimen can drain into the hollow spindle to the back pressure line. The diameter of the disc shall be about 1 mm less than the internal diameter of the cell. It… |
| 101 | 20.2.1.2.9 Rigid metal circular loading plate, with detachable lifting handle, to provide “equal strain” loading when required. A plug shall be provided to fill the central hole when necessary. 20.2.1.2.10 Peripheral drain, of porous plastics material of about 1.5 mm thick, for radial drainage tests. The inside face of the material shall be smooth. 20.2.1.2.11 Drainage disc, of porous plastics material up to 3 mm thick, for use as a drainage layer when two-way vertical drainage is used. 20.2.2 Instrumentation attached to the cell 20.2.2.1 A calibrated gauge or displacement transducer, referred to as the deformation gauge, complying with BS 1377-1:2016, 5.2.1.3. It shall be suitably supported for measuring the vertical compression or swelling of the specimen throughout the test… 20.2.2.2 A calibrated pore water pressure measuring device, consisting of a pressure transducer reading to 1 kPa mounted in a de-airing block fitted with an air bleed plug. One side of the block shall be fitted to the pore pressure valve on the cell b… 20.2.3 Ancillary equipment for preparation and operation of the cell 20.2.3.1 Two independent pressure systems, for applying and maintaining the desired pressure in the cell and in the specimen drainage line (referred to as the diaphragm pressure system and back pressure system respectively). They shall be capable of m… 20.2.3.2 A calibrated pressure transducer, for independent measurements of diaphragm pressure and back pressure, complying with BS 1377-1:2016, 5.2.1.7. They shall be capable of measuring the pressure to within 1 kPa or ±0.5 % for the full range of th… 20.2.3.3 A calibrated volume-change indicator, (burette, transducer or stepper motor type) complying with BS 1377-1:2016, 5.2.1.8, connected into the back pressure line. |
| 102 | 20.2.3.4 Suitable tubing, to connect the components of each pressure system to the cell. The expansion coefficient of the tubing due to internal pressure shall not exceed 0.001 mL/m for every1 kPa increase in pressure. 20.2.3.5 Timing device, readable to 1 s. 20.2.3.6 Materials, as follows: 20.2.3.7 Pressurized system for distribution of de-aerated water. 20.2.3.8 Immersion tank (optional), to enable the cell to be assembled under water. 20.2.3.9 A calibrated thermometer, readable to 0.5 C. 20.2.4 Equipment for specimen preparation and measurement 20.2.4.1 Procedures Procedures are given for the preparation of three types of specimen: 20.2.4.2 Equipment for preparation of specimen from an undisturbed sampling tube or block sample 20.2.4.2.1 Two cutting shoes, each clearly identified, having internal diameters as follows: 20.2.4.2.2 Extruder (for a sample taken in a sampling tube), suitable for ejecting the undisturbed sample from the sampling tube through the cutting shoe directly into the cell body. Extrusion shall be vertically upwards to avoid distortion of soft so… |
| 103 | 20.2.4.2.3 A means of holding the cell (for a block sample), with cutting ring and maintaining it in alignment while it is pushed into the block sample. 20.2.4.2.4 Balance, of sufficient capacity and accuracy to determine the mass of the specimen in the cell to an accuracy of within 0.1%. 20.2.4.2.5 Equipment for determination of water content (BS EN ISO 17892-1). 20.2.4.2.6 Equipment for determination of soil particle density (see BS EN ISO 17892-3). 20.2.4.2.7 Cutting and trimming tools, appropriate to the type of soil, such as: 20.2.4.2.8 A flat surface, about 500 mm square (or flat glass plate for the smallest size of cell). 20.2.4.2.9 Vernier or digital callipers, for measuring the internal diameter of cells up to 150 mm diameter. 20.2.4.2.10 A calibrated depth gauge, for measuring the height of the test specimen in the cell, readable to 0.1 mm. 20.2.4.2.11 Mandrel and guide jig, for forming a central drainage hole (required only for tests in which drainage takes place to the centre). 20.2.4.2.12 Fine sand, or other suitable drainage material, for use in a central drainage well. 20.2.4.2.13 A reference straightedge, such as an engineer’s steel rule. 20.2.4.3 Equipment for preparation of a specimen of compacted soil 20.2.4.3.1 The items listed in 20.2.4.3.2 to 20.2.4.3.6 are required for the preparation of soil and for compacting it into the consolidation cell, in addition to the items listed in BS 1377-1:2016, 8.2. 20.2.4.3.2 Test sieve of aperture size, approximately one-sixth of the height of the test specimens to be prepared. 20.2.4.3.3 Measuring cylinder. 20.2.4.3.4 Metal rammer, as described either in 11.3.2.2 (2.5 kg rammer), or in 11.5.2.2 (4.5 kg rammer), as appropriate. 20.2.4.3.5 Trimming tool, for preparing a flat surface on the specimen inside the cell at a given depth below the top end of the cell. 20.2.4.3.6 Items 20.2.4.2.4 to 20.2.4.2.12, as appropriate. 20.2.5 Calibration of cell 20.2.5.1 Measurements The following measurements of the cell and its accessories shall be determined and recorded; linear measurements shall be made to an accuracy of 0.5% and measurements of mass to an accuracy of 0.1%: |
| 104 | 20.2.5.2 Calibration of diaphragm 20.2.5.2.1 The force exerted by the diaphragm on a rigid top platen might be less than that calculated from the hydraulic pressure and cross-sectional area of the cell, owing to diaphragm stiffness and side friction. 20.2.5.2.2 The force applied by the diaphragm can be measured by the following method, which has been found to be satisfactory, but alternative methods may be used. |
| 105 | 20.2.6 Preparation and checking of apparatus 20.2.6.1 General Apparatus used for tests in the hydraulic cell shall be subjected to rigorous inspection and check testing before use. The checks described in 20.2.6.2 to 20.2.6.6 shall be carried out on the diaphragm pressure, back pressure and pore pressure systems… 20.2.6.2 Diaphragm pressures system (complete check) A pressure test of the diaphragm and its pressure system shall be made to ensure that the maximum test pressure stated in 20.2.1 can be maintained at all times during a test. 20.2.6.3 Back pressure system (complete check) 20.2.6.3.1 Flush freshly de-aerated water through the back pressure connecting line from the volume-change indicator and through the specimen drainage line. In this operation, work the indicator at least twice to its limits of travel, allowing water t… |
| 106 | 20.2.6.3.2 Seal the end of the drainage stem with a watertight plug. 20.2.6.3.3 Pressurize the back pressure to 750 kPa with the drainage line valve open and record the volume change indicator reading when steady. 20.2.6.3.4 Leave the system pressurized for at least 12 h and record the volume-change indicator reading again. 20.2.6.3.5 If the difference between the two readings, after deducting the volume change due to expansion of the tubing, does not exceed 0.1 mL the system can be considered to be leak-free and ready for a test. 20.2.6.3.6 If the corrected difference exceeds 0.1 mL, investigate the leaks and rectify them so that when 20.2.6.3.1 to 20.2.6.3.4 are repeated the requirement 20.2.6.3.5 is achieved. 20.2.6.4 Back pressure system (drainage stem or rim drain) (routine check) 20.2.6.4.1 Flush the back pressure line and drainage connections as in 20.2.6.3.1. Close the drainage line valve. 20.2.6.4.2 Increase the pressure in the back pressure system to 750 kPa, and record the volume change indicator reading after 5 min. 20.2.6.4.3 Proceed as in 20.2.6.3.4 to 20.2.6.3.6. 20.2.6.5 Pore pressure system (complete check) 20.2.6.5.1 Open the valve between the transducer mounting block and the flushing system. Pass freshly de-aerated water through the mounting block and cell base and out through the base port. Continue until no air bubbles are visible in the emerging wa… 20.2.6.5.2 Close the pore pressure valve on the cell base and then remove the bleed plug in the transducer mounting block. 20.2.6.5.3 Inject a solution of soap into the bleed plug hole. Open the flushing system valve so that water flows from the de-aerated supply and out of the bleed hole. 20.2.6.5.4 Screw the bleed plug back into the transducer mounting while water continues to emerge. 20.2.6.5.5 Open the pore pressure valve and allow about 500 mL of de-aerated water to pass out of the pore pressure measurement port (see note), then close the valve. 20.2.6.5.6 Seal the porous insert in the pore pressure measurement port, while water is emerging in order to avoid trapping air, by covering with a piece of latex rubber and a small flat metal disc held down by a clamping arrangement. 20.2.6.5.7 Pressurize the system to 700 kPa and again allow about 500 mL of water to pass out of the pore pressure measurement port. 20.2.6.5.8 Leave the system pressurized for at least 12 h. 20.2.6.5.9 After this period, check for leaks and if none are found, allow about 500 mL of water to pass out of the pore pressure measurement port. |
| 107 | 20.2.6.5.10 When checks confirm that the system is free of leaks, open the flushing system valve and the pore pressure valve and apply the maximum pressure achievable within the limitations of the pressure system and the pore pressure transducer to th… 20.2.6.5.11 Close the flushing system valve on the transducer mounting block and record the pore pressure reading. 20.2.6.5.12 If the pore pressure reading remains constant over a minimum of 6 h, the pore pressure connections can be assumed to be air and leak free. 20.2.6.5.13 If there is a decrease in the pressure reading, this indicates that there is a defect in the system, which shall be rectified. The complete pore pressure system check described above shall be repeated until the system is proved to be free … 20.2.6.5.14 Pass freshly de-aerated water through the connection to any ports in the cell base that are not to be used. When they are completely filled, close the valves on these lines and keep them closed throughout the test. 20.2.6.6 Pore pressure system (routine check) 20.2.6.6.1 Follow the procedures described in 20.2.6.5.1 to 20.2.6.5.9. 20.2.6.6.2 When checks confirm that the system is free of leaks, close the flushing system valve on the transducer mounting block. 20.2.6.6.3 Keep the cell base covered with de-aerated water until the test specimen is ready for setting up. 20.2.6.7 Porous media 20.2.6.7.1 The drainage disc shall be inspected and checked to ensure that water drains freely through it. A disc that is clogged by soil particles shall be rejected. 20.2.6.7.2 Boil porous insets for pore pressure measuring points in distilled/deionized water for the times stated in 20.2.6.7.1 before use and discard them when clogged with soil particles. 20.2.6.7.3 Boil porous plastic lining material in distilled water for at least 30 min before use. Place the smooth side towards the soil, but do not grease it. The material shall be used once only and then discarded. 20.2.6.7.4 Sand for use in a central drainage well shall be de-aerated by boiling in distilled water and allowed to cool in an airtight container. 20.3 Preparation of specimens 20.3.1 General 20.3.1.1 Types of specimen Test specimens shall be cylindrical with plane ends normal to the axis, and of a height/diameter ratio of 1/2.5 to 1/4. Specimens may be of undisturbed soil, or of disturbed soil that is compacted or compressed into the cell. |
| 108 | 20.3.1.2 Undisturbed specimens Specimens shall prepared by method 1 or method 2, depending on the type of sample. Method 2 may also be used for taking a specimen from a suitably trimmed exposure on site. 20.3.1.3 Compacted specimens Specimens shall be prepared by dynamic compaction (methods 3 and 4), or by static compression (method 5). These methods relate to compaction or compression into the larger sizes of consolidation cell. Specimens of smaller sizes can be trimmed from soi… 20.3.2 Preparation of undisturbed specimen from sample tube 20.3.2.1 Samples taken from site in tubes shall, whenever possible, be extruded, trimmed and fitted into the cell body in one operation. 20.3.2.2 Attach the cutting shoe of the correct diameter to the top end of the cell body, ensuring that the cutting edge is exactly in alignment with the cell wall. If the test is to be carried out with radial drainage to the periphery, fit the satura… 20.3.2.3 Assemble the sample tube and cell body with shoe on the extruder, ensuring correct alignment and secure fixing. |
| 109 | 20.3.2.4 Extrude the sample until the cell is filled with a few millimetres surplus at the top end. Remove parings from around the shoe during extrusion to prevent obstruction to movement of the sample. 20.3.2.5 Sever the sample at the level of the cutting edge of the shoe. 20.3.2.6 Detach the cell and shoe from the extruder and remove the cutting shoe. Support the underside of the specimen by spatula blades before lifting. 20.3.2.7 Trim the specimen at each end flush with the cell body flange. 20.3.2.8 Use a cylindrical spacer of appropriate thickness, and slightly smaller than the cell diameter, to push out the unwanted length of specimen; cut off this length. 20.3.2.9 Trim the cut end of the specimen (which will be the bottom face) flush with the upper edge of the cell. Remove any protruding particles carefully; fill the resulting void with fine material from the trimmings, and press in well. 20.3.2.10 Weigh the cell with the specimen to an accuracy of within 0.1%. Measure the distance from the surface of the specimen to the top end of the cell body to 0.5 mm and calculate the initial specimen height (Ho). 20.3.2.11 Cover the de-aired cell base (prepared as in 20.2.6.6) with a thin film of de-aerated water. 20.3.2.12 Place two thin steel spatulas under the bottom flange of the cell body to retain the specimen flush with the flange while it is lifted. Slide the specimen on to the flooded cell base without entrapping any air and remove the spatulas. Bolt t… 20.3.2.13 Fill the top of the cell above the specimen with de-aerated water only if the soil is not susceptible to swelling or is not sensitive to a water content change under zero stress. For a soil that is susceptible to swelling or sensitive to water content change, the swelling pressure shall be determined by the procedure in 20.5.1.1, by allowing water to percolate up from the base. 20.3.2.14 Take representative specimens from the soil trimmings for determination of water content in accordance with BS EN ISO 17892-1. 20.3.2.15 Assemble the cell top in accordance with 20.4. |
| 110 | 20.3.3 Preparation of specimen from block sample 20.3.3.1 The procedure given in 20.3.2.2 to 20.3.3.8 enables a specimen to be fitted into the cell body from a block sample, or from a specimen already extruded from a tube, or from a suitably trimmed exposure on site. 20.3.3.2 Trim the surfaces of the specimen level and reasonably flat. 20.3.3.3 Place the cell, fitted with plastics liner if needed and the appropriate cutting shoe, on the levelled surface, cutting edge down. 20.3.3.4 With a sharp blade trim the soil a few centimetres ahead of the shoe to about 3 mm larger than its internal diameter. 20.3.3.5 Push the cell downwards, keeping its axis vertical, so that the cutting shoe pares away the outer 1.5 mm or so of the soil. With soft soils the weight of a 250 mm cell alone may be enough to advance it downwards. For stiff soils, pre-trimming… |
| 111 | 20.3.3.6 Continue 20.3.3.4 and 20.3.3.5 until the cell is completely filled, with a few millimetres surplus projecting at the top. 20.3.3.7 Lift off the cell with specimen, underpinning it with spatulas, take off the cutting shoe, and complete the trimming as in 20.3.2.7 to 20.3.2.14. 20.3.3.8 Assemble the cell top in accordance with 20.4. 20.3.4 Preparation of soil for compacted specimens 20.3.4.1 Soil for compaction into a large consolidation cell shall be prepared as described in 20.3.4.2 to 20.3.4.5. 20.3.4.2 Remove any particles larger than one-sixth of the height of the specimen to be tested, by passing the soil through the appropriate sieve if necessary. 20.3.4.3 Bring the soil to the desired water content by thoroughly mixing with the appropriate amount of water, allowing for evaporation loss. 20.3.4.4 Take at least two representative specimens for determination of the water content. 20.3.4.5 Place the prepared soil in a sealed container, weigh to an accuracy of 0.1% and store for at least 24 h before use. 20.3.5 Compaction by specified compactive effort 20.3.5.1 The prepared and weighed soil is compacted into the cell and made ready for test as described in 20.3.5.2 to 20.3.5.14. 20.3.5.2 Attach the cell base to the body. The cell is first fitted with a peripheral drain if appropriate; the drainage material shall not be greased. 20.3.5.3 Close the valves between the cell and the pore pressure measuring system. 20.3.5.4 Place the cell assembly on a solid base, e.g. a concrete floor or plinth. 20.3.5.5 Place a quantity of prepared soil in the cell such that when compacted it occupies a little over one-half or one-third or one-fifth of the final specimen height, depending on the number of layers used. 20.3.5.6 Apply the requisite compactive effort equivalent to 2.5 kg compaction or 4.5 kg compaction (see 11.3 and 11.5). 20.3.5.7 Repeat 20.3.5.5 and 20.3.5.6 the appropriate number of times to produce a specimen of the required height. 20.3.5.8 Trim the top face of the compacted specimen to form a flat level surface, using a gauged depth trimming tool. Avoid tearing out hard particles. Return the trimmings to the remains of the prepared sample, and weigh the total remains to an accu… 20.3.5.9 Determine the mass of soil used in the specimen by difference. 20.3.5.10 Determine the height of the specimen (H0) to the nearest 0.5 mm by measuring down to the trimmed surface from the top of the cell body. 20.3.5.11 Take representative specimens from the remaining soil for determination of water content in accordance with BS EN ISO 17892-1. |
| 112 | 20.3.5.12 If the soil is susceptible to swelling or is sensitive to a water content change it shall not be covered with water. If the swelling pressure is to be determined the procedure in 20.5.1.1 shall be followed by allowing water to percolate up f… 20.3.5.13 Seal the specimen and allow it to stand for at least 24 h before starting a test, to enable excess pore pressures to dissipate. 20.3.5.14 Assemble the cell top in accordance with 20.4. 20.3.6 Compaction to a specified density 20.3.6.1 The procedure is similar to that given in 20.3.5 but is modified as described in 20.3.6.2 to 20.3.6.7. 20.3.6.2 Assemble and connect the cell body and base as in 20.3.5.2 and 20.3.5.3. 20.3.6.3 Calculate the mass of soil required to form a specimen of the desired height and volume from the specified density. 20.3.6.4 Weigh out this mass of soil from the prepared specimen. 20.3.6.5 Compact the soil into the cell in layers, using a controlled degree of compaction, so that it forms a homogeneous specimen of the desired height (see Note to 20.3.5.6). 20.3.6.6 Trim, measure and prepare the specimen as in 20.3.5.8 to 20.3.5.13. 20.3.6.7 Assemble the cell top in accordance with 20.4. 20.3.7 Preparation of specimen under static pressure 20.3.7.1 A specimen is prepared in the consolidation cell by static compression to give a specified dry density as described in 20.3.7.2 to 20.3.7.12. 20.3.7.2 Attach the cell base, prepared as in 20.2.6.6, to the body. First fit the cell with a peripheral drain if appropriate; the drainage material shall not be greased. 20.3.7.3 Close the valves between the cell and the pore pressure measuring system. 20.3.7.4 Place a weighed quantity of soil corresponding to one layer into the cell and spread it evenly, using a tamping rod if appropriate. 20.3.7.5 Place suitable spacer blocks on the soil and apply a static load until the required height of soil is formed. 20.3.7.6 Repeat 20.3.7.4 and 20.3.7.5 for succeeding layers until the specimen is of the required height. 20.3.7.7 Level the surface of the specimen as in 20.3.5.8 and weigh any soil removed. Determine the mass of specimen by difference. 20.3.7.8 Verify the height of the specimen (H0) to the nearest 0.5 mm by measuring down to the trimmed surface from the top of the cell body. 20.3.7.9 Take representative specimens from the remaining soil for determination of water content in accordance with BS EN ISO 17892-1. 20.3.7.10 If the soil is susceptible to swelling or is sensitive to a water content change it shall not be covered with water. If the swelling pressure is to be determined the procedure in 20.5.1.1 shall be followed by allowing water to percolate up f… |
| 113 | 20.3.7.11 Seal the specimen and allow it to stand for at least 24 h before starting a test, to enable excess pore pressures to dissipate. 20.3.7.12 Assemble the cell top in accordance with 20.4. 20.4 Cell assembly 20.4.1 General Before the cell can be finally assembled the operations given in one of 20.4.2 to 20.4.5 shall be carried out, depending on the type of test to be performed. These operations follow on from the preparation of the specimen (see 20.3) and relate to 20.5… 20.4.2 Consolidation with vertical drainage and pore pressure measurement 20.4.2.1 “Free strain” loading 20.4.2.1.1 Place a saturated flexible porous disc centrally on the surface of the specimen, without entrapping air. 20.4.2.1.2 Pore pressure and drainage connection are as shown in Figure 23. The rim drain valve remains closed. 20.4.2.1.3 Cover the specimen and porous disc with de-aerated water, as appropriate. 20.4.2.2 “Equal strain” loading 20.4.2.2.1 Place a porous disc on top of the specimen, followed by the rigid loading plate. Avoid entrapping air. Ensure that the central hole of the plate aligns with the hole in the drainage spindle. 20.4.2.2.2 Pore pressure and drainage connections are as in 20.4.2.1. 20.4.2.2.3 Cover the specimen and porous disc with de-aerated water, if appropriate. 20.4.3 Consolidation with two-way vertical drainage 20.4.3.1 The procedure is similar to that given in 20.4.2.2, with the following variations. 20.4.3.2 Before transferring the specimen to the cell base (see 20.3.2.12), place a saturated porous disc of the specimen diameter on the base, without entrapping air. 20.4.3.3 When tightening the cell body on to the base allow the thickness of the disc to displace the specimen upwards. 20.4.3.4 Allow for the thickness of the disc when measuring the specimen height, and the mass of the disc when weighing. Otherwise the setting-up procedure is the same as in 20.3.2, and 20.4.2.1 or 20.4.2.2. 20.4.3.5 The flushing system valve (see Figure 23) is connected to the same back pressure system as the back pressure valve and becomes the bottom drainage valve. Pore pressures are not measured. The volume-change indicator measures the total volume o… |
| 114 | 20.4.3.6 Cover the specimen and porous disc with de-aerated water, if appropriate. 20.4.4 Consolidation with outward radial drainage 20.4.4.1 The procedure is similar to that given in 20.4.2, with the variations given in 20.4.4.2 to 20.4.4.6. 20.4.4.2 Fit a lining of porous plastics material against the cell wall, to act as a peripheral drain, before inserting the specimen. 20.4.4.3 Place an impervious membrane, such as a disc of latex rubber, on the surface of the specimen without entrapping air. For a “free strain” test the membrane shall be flexible. 20.4.4.4 For and “equal strain” test, place the circular steel plate on top of the membrane without entrapping air, and plug the central hole. 20.4.4.5 Connect the back pressure system to the rim drain valve (see Figure 25a), through which drainage takes place. The back pressure valve is not used and remains closed, with the connection between it and the end of the hollow stem filled with de… 20.4.4.6 Cover the specimen and porous disc with de-aerated water, if appropriate. 20.4.5 Consolidation with inward radial drainage 20.4.5.1 The procedure is similar to that given in 20.4.2 with the variations given in 20.4.5.2 to 20.4.5.10.and set up according to Figure 25b). 20.4.5.2 Pore pressure shall be measured at a point offset from the centre, usually 0.55 R from the centre, where R is the radius of the specimen. The central point is used for drainage, and the pore pressure valve is connected to the back pressure sy… 20.4.5.3 The back pressure valve and the rim drain valve are not used for consolidation, but the rim drain valve is used to make connection with the porous periphery during a permeability stage, and remain closed. 20.4.5.4 Immediately after trimming the surface of the specimen form a vertical hole in its centre by using a suitable mandrel. 20.4.5.5 Flush the hole with de-aerated water upwards from the central base port to ensure that there is no obstruction and no smeared material remaining on the porous insert. 20.4.5.6 Add clean de-aerated water to the hole to approximately two-thirds full. 20.4.5.7 Place the saturated sand (prepared as in 20.2.6.7.4) steadily into the hole through a tube, so as to obtain a loose state of packing. Avoid jolting or vibrating the cell after placing. 20.4.5.8 When the hole is full check that water drains freely through the sand and out through the pore pressure valve, keeping the sand saturated. Trim the top surface of the specimen if necessary and cover with de-aerated water if appropriate. 20.4.5.9 For a “free strain” test place an impervious flexible disc on top of the specimen without entrapping air. 20.4.5.10 For an “equal strain” test place the circular steel plate on top of the specimen without entrapping air and plug the central hole. |
| 115 | 20.4.6 Fitting the cell cover 20.4.6.1 After preparing the specimen for test in the cell by one of the methods given above fit the cell cover to the cell body over a sink or large tray, as described in 20.4.6.2 to 20.4.6.5. 20.4.6.2 Support the cell cover over the cell body and partly fill the diaphragm with water so that it can be lowered into the cell without creasing. 20.4.6.3 Bolt the cell cover to the body, tightening the bolts evenly ensuring that the flange of the diaphragm is properly seated between them. 20.4.6.4 Fill the space above the diaphragm with water, displacing air through the air bleed, which is connected to a moderate vacuum to facilitate removal of all the air. 20.4.6.5 Apply a small seating pressure, pd0 (not exceeding 10 kPa), to the diaphragm. Open the rim drain valve momentarily to release excess water from behind the diaphragm and to ensure that it remains seated on the disc covering the specimen. 20.4.7 Final adjustments 20.4.7.1 Adjustments necessary before starting the test, and initial observations, are as described in 20.4.7.2 to 20.4.7.8. 20.4.7.2 Ensure that the flushing system valve remains closed throughout the test, so as to isolate the pore pressure transducer from the flushing system. 20.4.7.3 Secure the deformation indicator in position with the stem properly seated, allowing for a small upward movement. 20.4.7.4 Record the compression gauge reading as the datum value corresponding to the diaphragm seating pressure, pd0. 20.4.7.5 Record the initial steady pore water pressure, u0, corresponding to pd0. 20.4.7.6 From the diaphragm pressure calibration data ascertain the pressure, po, applied to the specimen corresponding to the diaphragm seating pressure, pd0. 20.4.7.7 Set the back pressure system to the desired value, not less than u0, keeping the appropriate drainage line valve closed. 20.4.7.8 Record the reading of the volume-change indicator on the back pressure line when equilibrium is established. 20.5 Procedure for consolidation test with one-way vertical drainage |
| 116 | 20.5.1 Saturation 20.5.1.1 Measurement of swelling pressure A soil that is susceptible to swelling shall not be allowed free access to water without provision for applying a vertical confining stress to prevent swell. Initial saturation is effected by allowing de-aerated water to enter at the base and to perco… 20.5.1.2 Saturation procedure 20.5.1.2.1 Apply increments of diaphragm and back pressure alternately. The diaphragm pressure increment stages shall be carried out without allowing drainage into or out of the specimen, which enables values of the pore pressure ratio u/σ to be det… 20.5.1.2.2 Record the initial pore water pressure (u0) as soon as it has reached a steady value after applying the pressure on the specimen corresponding to the diaphragm seating pressure . Ensure that the back pressure valve (see Figure 23) is closed. 20.5.1.2.3 Increase the diaphragm pressure to give the required first stage pressure on the specimen (p1). 20.5.1.2.4 Calculate the value of ratio δu/δσ from the formula: |
| 117 | 20.5.1.2.5 Keeping the back pressure valve closed, increase the pressure in the back pressure line to a value equal to the vertical pressure 1 less the selected differential pressure (see Note 2 to 20.5.1.1). Record the reading of back pressure line… |
| 118 | 20.5.1.2.6 Open the back pressure valve to admit the back pressure into the specimen. 20.5.1.2.7 Observe the pore pressure and the volume-change indicator readings. When the pore water pressure becomes equal to the applied back pressure, and the volume-change indicator shows that movement of water into the specimen has virtually ceased… 20.5.1.2.8 Calculate the volume of water taken in by the specimen during this increment from the difference between v1 and v2. 20.5.1.2.9 Increase the diaphragm pressure by a further increment to give a pressure increase on the specimen of δσ Observe the resulting change in pore pressure δμ, as in 20.5.1.2.3 When equilibrium is established calculate the new value of δμ/δσ. 20.5.1.2.10 Repeat the operations described in 20.5.1.3.5 to 20.5.1.3.9 until the pore pressure ratio δμ/δσ indicates that saturation is achieved. 20.5.1.2.11 The specimen is considered to be saturated when the value of δμ/δσ is equal to or greater than 0.95, or such other value appropriate to the soil type (see commentary on 20.5.1). 20.5.1.2.12 Calculate the total volume of water taken up by the specimen into the air voids by totalling the differences obtained from 20.5.1.3.8. |
| 119 | 20.5.1.2.13 A graph of δμ/δσ against diaphragm pressure at the end of each increment, or against pore pressure responses to cell pressure changes, may be plotted. 20.5.2 Undrained loading 20.5.2.1 Each increment of load is applied to the specimen with the drainage valve closed. The additional applied stress is carried by the consequent increase in pore water pressure which is monitored during this build-up stage. 20.5.2.2 Record the initial readings of pore pressure, the compression gauge and the pressure applied to the diaphragm. 20.5.2.3 Close the diaphragm pressure valve and set the diaphragm pressure line to the value needed to give the desired vertical stress on the specimen, taking into account the diaphragm calibration (see 20.2.5.2). 20.5.2.4 Open the diaphragm pressure valve to admit the pressure to the diaphragm, and at the same instant start the timer. 20.5.2.5 Observe and record readings of the pore pressure transducer at suitable intervals of time for plotting a curve of pore pressure build-up against time. 20.5.2.6 Open and close the rim drain valve to allow escape of excess water from behind the diaphragm into a measuring cylinder. 20.5.3 Consolidation (drained stage) 20.5.3.1 Consolidation is effected by opening the drainage valve, which allows water to drain from the specimen while the applied stress is transferred to the soil “skeleton”, i.e. the effective stress increases. Pore pressure changes, volume changes … 20.5.3.2 Record the diaphragm pressure and back pressure, and the initial readings of pore pressure, the compression gauge and the volume-change indicator corresponding to zero time. 20.5.3.3 Open the back pressure valve thus permitting drainage and at the same instant start the timer. 20.5.3.4 Record readings of pore pressure, the compression gauge and the volume-change indicator at suitable intervals of time after opening the drainage valve. Intervals of 0, ¼, ½, 1, 2, 4, 8, 15, 30, 60 min; 2, 4, 8, 24 h, are convenient for plotti… |
| 120 | 20.5.3.5 Hold the applied pressure constant until the pore pressure dissipation (calculated as in 20.5.7.2) eaches at least 95% (see Note 1). Pore pressure dissipation of 100% represents the end of primary consolidation (see Note 2). 20.5.3.6 Close the back pressure valve to terminate the load stage. Record the final readings of pore pressure, settlement gauge and volume-change indicator. 20.5.3.7 Increase the diaphragm pressure to give the next vertical stress on the specimen, as described in 20.5.2.2 o 20.5.2.6. 20.5.3.8 Allow consolidation as in 20.5.3.1 to 20.5.3.6. 20.5.3.9 Repeat 20.5.3.7 and 20.5.3.8 for each value of applied stress in the desired loading sequence. 20.5.4 Unloading 20.5.4.1 After completing the consolidation stage under the maximum applied pressure record the final readings and close the back pressure valve. 20.5.4.2 Unload the specimen in a sequence of decrements of diaphragm pressure (see Note), similar in principle to the procedures described in 20.5.2 and 20.5.3. However, in each undrained stage, the pore pressure decreases to a steady value, and in e… 20.5.4.3 When equilibrium is established at an applied stress equal to the initial seating pressure, record the readings of pore pressure, compression gauge and volume-change indicator and close the pore pressure valve and the back pressure valve. 20.5.5 Dismantling and final measurements 20.5.5.1 Open the back pressure valve and the rim drain valve to the atmosphere to allow surplus water to escape, reduce the diaphragm pressure to zero, and remove the cell top and drainage disc (and loading plate if used). Remove any free water from … 20.5.5.2 Using a straightedge placed across the top edge of the cell body, measure down to the surface of the specimen at several points using a steel rule or depth gauge to an accuracy of 0.5% to obtain a surface profile, from which the final volume … |
| 121 | 20.5.5.3 Weigh the specimen in the cell body to an accuracy of 0.1%. 20.5.5.4 Remove the specimen from the cell and take representative portions from two or more points for determination of final water content. 20.5.5.5 Break open a representative portion of the specimen on a vertical line for detailed examination and description of the soil. Record details of the soil fabric by sketches and, if required, by colour photographs. 20.5.6 Graphical plots 20.5.6.1 Loading stage Plot the following graphs for each loading stage: 20.5.6.2 Unloading stage Plot the following graphs for each unloading stage: 20.5.6.3 End of test Plot the voids ratio at the end of each drained loading or unloading stage (calculated as described in 20.5.7.3), if required, as ordinates against applied effective stress on a logarithmic scale as the abscissa (the e/log’ curve). 20.5.7 Calculations and analysis of data 20.5.7.1 Initial specimen data 20.5.7.1.1 Calculate the initial bulk density of the specimen, (in Mg/m3), from its initial measurements and mass. 20.5.7.1.2 Using the initial water content, wo (%), determined from trimmings, calculate the initial dry density, (in Mg/m3), from the formula: 20.5.7.1.3 Calculate the initial voids ratio (eo) if required from the formula: |
| 122 | 20.5.7.1.4 Calculate the initial degree of saturation. So (%), if required from the formula: 20.5.7.2 Pore pressure dissipation 20.5.7.3 Voids ratio (if required) 20.5.7.3.1 For tests with “equal strain” loading, changes in voids ratio can be related to changes in vertical settlement by the formula: 20.5.7.3.2 For tests with “free strain” loading (and optionally for “equal strain” loading), changes in voids ratio might be calculated from measured volume of water draining out of the specimen using the formula: |
| 123 | 20.5.7.4 Compressibility 20.5.7.4.1 For tests with “equal strain” loading, calculate the coefficient of volume compressibility, mv (in m2/MN), from the formula: 20.5.7.4.2 For tests with “free strain” loading, calculate the coefficient of volume compressibility, mv (in m2/MN) for each consolidation stage from the formula: |
| 124 | 20.5.7.5 Coefficient of consolidation 20.5.7.5.1 Method (a): Pore pressure dissipation From the graph of pore pressure dissipation against log time for each loading stage, read off the time t50 (in min) corresponding to a dissipation of 50%. Calculate cv (in m2/year) from the formula: 20.5.7.5.2 Method (b): Log time curve fitting On the initial (convex upwards) portion of the plot of settlement against log time, locate the theoretical zero point (denoted by do) as follows (see Figure 5). |
| 125 | 20.5.7.5.3 Method (c): Square-root time curve fitting (see note 2 to 20.5.7.5.2) On the plot of settlement against square-root time (see Figure 27) for each loading stage, draw the straight line which best fits the approximately linear early portion (within about the first 50% primary consolidation) and extend it to intersect the … |
| 126 | 20.5.7.5.4 Temperature correction If the average laboratory temperature during a consolidation stage differs by more than ±2 C from 20 C, the derived value of cv shall be corrected to the 20 C value by multiplying the appropriate correction factor obtained from Figure 28. 20.5.7.6 Coefficient of secondary compression 20.5.7.6.1 Extend the linear portion of the secondary compression portion of the curve (see Figure 5) so that it covers one complete cycle of log time. It may be necessary to prolong the duration of the load increment to establish a linear relationship. 20.5.7.6.2 Read off the compression gauge readings at the beginning and end of the cycle, e.g. at 1 000 min and 10 000 min, and calculate the difference, ()s (in mm), between them. 20.5.7.6.3 Calculate the coefficient of secondary compression, Csec, from the formula: 20.5.7.6.4 Repeat 20.5.7.6.1 to 20.5.7.6.3 for each of the applied loading stages. 20.5.8 Test report The test report shall affirm that the test was carried out in accordance with this British Standard, 20.5, and shall contain the following information, in addition to the relevant information listed in BS 1377-1:2016, Clause 10: |
| 128 | 20.6 Procedure for consolidation test with two-way vertical drainage 20.6.1 Saturation If during the saturation stage the bottom drainage valve (see Figure 23) remains closed, the conditions are similar to those referred to in 20.5.1. Apply saturation as described in 20.5.1. 20.6.2 Undrained loading When a load increment is applied by increasing the diaphragm pressure, leave the bottom drainage valve and the back pressure valve (Figure 23) closed so that pore water pressure build-up can be observed and recorded as described in 20.5.2. |
| 129 | 20.6.3 Consolidation (drained stage) Effect consolidation by opening both the top and bottom drainage valves at the same time as the timer is started. Proceed as in 20.5.3 except that pore pressure changes cannot be observed. 20.6.4 Unloading Unload the specimen in decrements, as described in 20.5.4, except that pore water pressure can be observed only during the undrained unloading stage. Judge the equilibrium condition at the end of a drained swelling stage from volume-change readings of… 20.6.5 Dismantling and final measurements Proceed as in 20.5.5. 20.6.6 Graphical plots 20.6.6.1 During each loading stage. Proceed as in 20.5.6.1, except that item c) is not applicable. 20.6.6.2 During each unloading stage. Proceed as in 20.5.6.2, except that item c) is not applicable. 20.6.6.3 End of test. Proceed as in 20.5.6.3. 20.6.7 Calculations and analysis of data 20.6.7.1 Calculations Carry out calculations in accordance with 20.5.7.1 and 20.5.7.3 to 20.5.7.6. In calculating values of cv (see 20.5.7.5), use only methods (b) or (c) with the following modifications. 20.6.7.2 Method (b): Log time curve fitting Calculate cv from the formula: 20.6.7.3 Method (c): Square-root time curve fitting Calculate cv from t50 as in method (b) above, or from t90 using the formula: 20.6.7.4 Temperature correction |
| 130 | 20.6.8 Test report The test report shall affirm that the test was carried out in acccordance with this British Standard, 20.6. It shall include the information as listed in 20.5.8, except for data relating to pore pressure measurements. 20.7 Procedure for consolidation test with drainage radially outwards 20.7.1 Saturation Carry out the saturation procedure as described in 20.5.1.2 except that the back pressure is applied through the rim drain valve (see Note 2 of 20.3.1.2). 20.7.2 Undrained loading Apply increments of loading and observe the build-up of pore water pressure, as in 20.5.2. In 20.5.2.6 excess water can be allowed to escape from behind the diaphragm by momentarily opening the rim drain valve and measuring the volume of water thus re… |
| 131 | 20.7.3 Consolidation (drained stage) Initiate consolidation by opening the rim drain valve. Otherwise proceed and record data as in 20.5.3 for each stage of consolidation. 20.7.4 Unloading Carry out decremental unloading as in 20.5.4 except that the rim drain valve is used instead of the back pressure valve. 20.7.5 Dismantling and final measurements Proceed as in 20.5.5. Discard porous plastics material used as the peripheral drain. 20.7.6 Graphical plots 20.7.6.1 Loading stage Plot graphs for each loading stage as described in 20.5.6.1, except for the square-root time method of item b) when “free strain” loading is used. In this case, plot settlement and volume change against t0.465 instead of t0.5, where t is the elapsed t… 20.7.6.2 Unloading stage Plot graphs for each unloading stage as in 20.5.6.2, except for item b) when “free strain” loading is used. In this case t0.465 shall be used instead of t0.5. 20.7.6.3 End of test Proceed as in section 20.5.6.3. 20.7.7 Calculations and analysis of data 20.7.7.1 General Carry out calculations of initial specimen data, pore pressure dissipation, voids ratios and coefficient of volume compressibility as in 20.5.7.1 to 20.5.7.4. 20.7.7.2 Method (a): Pore pressure dissipation Calculate cro (m2/year) from one of the following formulas, as applicable: |
| 132 | 20.7.7.3 Method (b): Log time curve fitting Calculate cro (m2/year) from one of the following formulas, as applicable: 20.7.7.4 Method (c): “Free strain” loading (special power curve fitting) From the graph of volume change against t0.465 obtain the point corresponding to zero theoretical primary consolidation (represented by do) in the same way as in 20.5.7.5.3. Draw the straight line through the do point which at all points has abscissae… 20.7.7.5 Method (d): “Equal strain” loading (square-root time curve fitting) Derive t50 and t90 as in 20.5.7.5 using square-root time as the abscissa for the plot, except that the line drawn through the do point has abscissae 1.17 (instead of 1.15) times those of the best fit line. In Figure 6, for this type of test m = 1.17 a… 20.7.7.6 Temperature correction A temperature correction shall be applied to the calculated value of cro, if appropriate, as in 20.5.7.5.4. 20.7.8 Test report The test report shall affirm that the test was carried out in accordance with this British Standard, 20.7 and shall contain the following information, in addition to the relevant information listed in BS 1377-1:2016, Clause 10: |
| 133 | 20.8 Procedure for consolidation test with drainage radially inwards |
| 134 | 20.8.1 Saturation Carry out the saturation procedures as described in 20.5.1 except that the back pressure is applied through the central base drainage port. 20.8.2 Undrained loading Apply increments of loading and observe the build-up of pore water pressure as in 20.5.2 except that pore water pressure is measurement off-centre. 20.8.3 Consolidation (drained stage) Initiate consolidation by opening the central base drainage valve. Measure pore water pressure offset from centre. Otherwise proceed and record data as described in 20.5.3 for each stage of consolidation. 20.8.4 Unloading Carry out decremental unloading as in 20.5.4 but with base drainage. 20.8.5 Dismantling and final measurements Proceed as in 20.5.5. The central drainage material shall be discarded and not re-used. 20.8.6 Graphical plots Plot graphs during each loading and unloading stage, and at the end of test, as described in 20.5.6. 20.8.7 Calculations and analysis of data 20.8.7.1 General Carry out calculations of initial specimen data, pore pressure dissipation, voids ratios and coefficient of volume compressibility as in 20.5.7.1 to 20.5.7.4. 20.8.7.2 Method (a): Pore pressure dissipation |
| 135 | 20.8.7.3 Method (b): Log time curve fitting Calculate cri (m2/year) from the same formula as in 20.8.7.2. 20.8.7.4 Method (c): Square-root time curve fitting 20.8.7.5 Temperature correction Apply a temperature correction to the calculated value of cri, if appropriate, as in 20.5.7.5.4. 20.8.8 Test report The test report shall affirm that the test was carried out in accordance with this British Standard, 20.8 and shall contain the following information, in addition to the relevant information in BS 1377-1:2016, Clause 10: |
| 136 | 21 Determination of permeability in a hydraulic consolidation cell 21.1 General 21.1.1 Test conditions The following test conditions shall be specified before starting a test: |
| 137 | 21.1.2 Environmental requirements and safety 21.1.2.1 Temperature These tests shall be carried out in a laboratory in which the temperature is maintained constant to within ±2 C, in accordance with BS 1377-1:2016, 7.1. All apparatus shall be protected from direct sunlight, from local sources of heat and from draughts. 21.1.2.2 Hazard warning 21.2 Apparatus for preparation of specimens 21.3 Apparatus for permeability test 21.3.1 Hydraulic consolidation cell. The hydraulic consolidation cell and its accessories and instrumentation are described in 20.2.1 to 20.2.3. 21.3.2 Ancillary equipment for permeability tests in the cell 21.3.2.1 Three independent pressure systems, as specified in 20.2.3.1 for applying and maintaining the desired pressures for the following: 21.3.2.2 A calibrated pressure transducer, for independent calibrated measurements of the pressure in each pressure system, as specified in 20.2.3.2, except that the transducer shall be connected to the three pressure systems. Alternatively, independe… |
| 138 | 21.3.2.3 Two calibrated volume-change indicators (burette or transducer type), one on each of the drainage lines connected to the specimen, as specified in 20.2.3.3. 21.3.2.4 Timing device, readable to 1 s. 21.3.2.5 A plentiful supply of de-aerated tap water, at room temperature. 21.3.2.6 Silicone grease or petroleum jelly. 21.3.2.7 For vertical permeability tests: 21.3.2.8 For horizontal permeability tests. 21.3.2.9 A calibrated thermometer, readable to 0.5 C. 21.4 Calibration of apparatus 21.4.1 Measurements. Determine the dimensions of the cell and accessories as in 20.2.5.1. 21.4.2 Calibration of diaphragm. Calibrate the force exerted by the diaphragm as in 20.2.5.2. 21.4.3 Head losses 21.4.3.1 General. Determine the head losses in pipelines and other restrictions, for various rates of flow of water, as follows. 21.4.3.2 For tests with vertical flow, assemble and connect the cell as described in 21.7.2, except that the cell is filled with water instead of a soil specimen and spacer blocks separate the two discs of porous material. 21.4.3.3 For tests with radial flow, assemble and connect the cell as described in 21.7.3, except that the cell is filled with fine uniform gravel and the central drainage well of fine sand is wrapped in mesh fine enough to retain the finest particles. 21.4.3.4 Apply a suitable seating pressure to the diaphragm. 21.4.3.5 Adjust the pressure in the inlet and outlet drain pressure systems (kPa) and (kPa) respectively to give a small difference, measured with a differential pressure gauge or manometer. Both pressures should be significantly less than the diaph… |
| 139 | 21.4.3.6 Open the appropriate inlet and outlet valves and start the timer. Record readings of the volume change gauges on both lines at regular intervals of time. 21.4.3.7 Plot a graph of the cumulative volume of water, Q (mL), as recorded from each volume change gauge, as ordinates, against time (in min) as abscissae. Continue until the relationship is linear and the two lines are parallel. 21.4.3.8 From the linear relationship bewteen Q and time, determine the slope, which gives the mean rate of flow, q (mL/min). 21.4.3.9 Repeat steps 21.4.3.5 to 21.4.3.8 at least three more times over a range of rates of flow, q, which covers the likely rates of flow to be encountered in a series of tests. 21.4.3.10 Plot the results as a graph of pressure difference, (σ1 – σ2) (denoted by σc) as ordinate, against rate of flow, q, as abscissa. This is the calibration graph referred to in 21.9.1.3 and 21.9.2.2. 21.5 Preparation and checking of apparatus Prepare and check the cell and ancillary items as described in 20.2.6. 21.6 Preparation of test specimen Prepare the test specimen by one of the methods described in 20.3, as appropriate to the type of specimen and method of test. 21.7 Assembly of cell 21.7.1 General Assemble the cell with specimen generally as described in 20.4.1. The rigid loading plate is normally placed on top of the specimen to maintain a uniform thickness of soil. Detailed requirements for the two types of test are described in 21.7.2 to 21…. 21.7.2 Test with vertical flow 21.7.2.1 Assemble the cell as described in 20.4.3 (with reference to 20.4.2.2). The top and bottom faces of the specimen are in contact with a porous disc. 21.7.2.2 Connect the inlet pressure line to the back pressure valve, and the outlet pressure line to the pore pressure valve, without entrapping air, to give flow vertically downwards through the specimen. 21.7.3 Tests with radial flow 21.7.3.1 Assemble the cell as described in 20.4.4 (with reference to 20.4.2.2.1 and 20.4.2.2.3). The periphery of the specimen is in contact with the porous plastic material. 21.7.3.2 Install the central drain as described in 20.4.5.4 to 20.4.5.8. 21.7.3.3 Place the rigid circular steel plate on top of the specimen and plug the central hole. Do not permit drainage from the top and bottom faces of the specimen. 21.7.3.4 For outwards flow of water, connect the inlet pressure line to the pore pressure valve and the outlet to the rim drain valve, without entrapping air. 21.7.3.5 For inward flow of water, reverse the above connections. 21.7.4 Final assembly and adjustments 21.7.4.1 Fit the cell cover to the cell body as described in 20.4.6. 21.7.4.2 Make final adjustments and initial observations as described in 20.4.7.3 to20.4.7.8. |
| 140 | 21.8 Test procedures 21.8.1 Saturation Saturate the specimen by the procedure given in 20.5.1.2. When applying an increment of diaphragm pressure to determine the value of the ratio , ensure that the pore pressure valve is closed. 21.8.2 Consolidation 21.8.2.1 Consolidate the specimen to achieve the desired effective stress, as described in 21.8.2.2 to 21.8.2.4. 21.8.2.2 For a vertical flow test, follow the procedures of 20.6.3 and 20.6.4. Evaluate the results, if necessary, as in 20.6.6 and 20.6.7 21.8.2.3 For a radial flow test with outward flow, follow the procedures in 20.7.3 and 20.7.4. Evaluate the results, if necessary, as in 20.7.6 and 20.7.7. 21.8.2.4 For a radial flow test with inward flow follow the procedures in 20.8.3 and 20.8.4. Evaluate the results, if necessary, as in 20.8.6 and 20.8.7. 21.8.3 Measurement of vertical permeability 21.8.3.1 Carry out a permeability test with flow vertically downwards on the consolidated specimen as described in 21.8.3.2 to 21.8.3.10. 21.8.3.2 With the pore pressure valve and the back pressure valve closed adjust the pressure in the outlet drain line connected to the pore pressure valve, p2 (in kPa), to equate with the back pressure, p1 (in kPa), already applied to the top of the s… 21.8.3.3 Increase the pressure σ1 to a value such that the pressure difference (p1 – p2) is equal to the desired pressure difference across the specimen for the permeability test (see note). The difference between the diaphragm pressure pd (kPa) and p… |
| 141 | 21.8.4 Measurement of horizontal permeability 21.8.4.1 Carry out a permeability test with horizontal flow radially outwards on the consolidated specimen as described in 21.8.4.2 to 21.8.4.10. For flow radially inwards the procedure is similar but with the inlet and outlet connections interchanged. 21.8.4.2 The back pressure valve remains closed. With the pore pressure valve and the rim drain valve closed adjust the pressure in the outlet drain line connected to the pore pressure valve, 21.8.4.3 Increase the pressure p1 to a value such that the pressure difference () is equal to the desired pressure difference across the specimen for the permeability test (see Note to 21.8.3.3). The difference between the diaphragm pressure (in kPa… 21.8.4.4 Record the readings of the volume-change indicators in the inlet and outlet pressure lines when they reach steady values. 21.8.4.5 Open the rim drain valve and start the timer. Record readings of both volume-change indicators at suitable regular intervals of time. The mean effective vertical stress for the test is equal to . 21.8.4.6 Plot a graph of the cumulative volume of water flowing through the specimen, Q (in mL), as recorded from each volume change indicator, as ordinates, against time (in min) as abscissae. Continue to test until the relationship is linear and the… 21.8.4.7 Record the temperature in the vicinity of the consolidation cell to ±0.5 C. 21.8.4.8 Stop the test by closing the pore pressure valve and the rim drain valve. 21.8.4.9 If an additional test at a lower effective stress is required, repeat 21.8.4.2 to 21.8.4.8 with the values of and increased as appropriate. 21.8.4.10 If an additional test at a higher effective stress is required, consolidate the specimen as in 21.8.2, using the appropriate pressures, and repeat 21.8.4.2 to 21.8.4.8. 21.9 Calculations 21.9.1 Vertical permeability 21.9.1.1 Calculate the circular area of cross section of the soil specimen, A (in mm2). 21.9.1.2 From the graphs plotted in 21.8.3.6 or 21.8.4.6, determine the mean slope of the linear portion, which is equal to the mean rate of flow, q (in mL/min), during steady flow conditions in the test. 21.9.1.3 From the calibration graph derived as in 21.4.3.9, determine the pressure difference, pc (in kPa), corresponding to the rate of flow q in the test. 21.9.1.4 Calculate the coefficient of permeability, kv (in m/s), at 20 C, from the formula: |
| 142 | 21.9.2 Horizontal permeability 21.9.2.1 From the graphs plotted in 21.8.3.6 determine the mean slope of the linear portion, which is equal to the mean rate of flow, q (in mL/min), during steady flow conditions in the test. 21.9.2.2 From the calibration graph derived as in 21.4.3.10, determine the pressure difference, pc (in kPa), corresponding to the rate of flow q in the test. 21.9.2.3 Calculate the coefficient of permeability in the horizontal direction, kH (in m/s), at 20 C from the formula: 21.10 Test report |
| 143 | 22 Determination of isotropic consolidation properties using a triaxial cell 22.1 Test method The test shall be carried out in accordance with BS EN ISO 17892-9 following the specimen preparation, saturation and consolidation procedures in BS EN ISO 17892-9:2018, 6.1 to 6.4, 6.6 and 6.8. 22.2 Calculations 22.2.1 General initial data 22.2.1.1 Calculate the initial water content, w0 (%), from the formula: 22.2.1.2 Calculate the initial dry density, d (in Mg/m3) from the formula: 22.2.1.3 Calculate the initial bulk density, (in Mg/m3) from the formula: 22.2.1.4 Calculate the initial voids ratio, e0, if required, from the formula: |
| 144 | 22.2.1.5 Calculate the initial degree of saturation, S0, if required, as a percentage from the formula: 22.2.2 Saturation data 22.2.2.1 If saturation was achieved by the application of increments of back pressure, plot the calculated value of the pore pressure coefficient B, calculated from BS EN ISO 17892-9:2018, Formula (1) against pore pressure or cell pressure. 22.2.3 Consolidation data 22.2.3.1 For each undrained phase calculate the value of the pore pressure coefficient B from BS EN 17982-9:2018, Formula (1). 22.2.3.2 Plot the pore pressure at the end of each undrained phase and each drained phase against cell confining pressure. 22.2.3.3 For each drained phase plot the: 22.2.3.4 From each graph given by 22.2.3.3 b) read off the time, t50 (minutes) corresponding to 50% pore pressure dissipation. 22.2.3.5 Calculate the height of specimen H (in mm) at the end of each consolidation stage from the formula: 22.2.3.6 Calculate the voids ratio, e, if required, at the end of each consolidation stage from the formula: |
| 145 | 22.2.3.7 Calculate the coefficient of volume compressibility for isotropic consolidation, 22.2.3.8 Calculate the value of the coefficient of consolidation for isotropic consolidation, cvi (in m2/year), for each stage from the formula: 22.2.3.9 If appropriate apply a temperature correction to the calculated value of cvi, as described in 20.5.7.5.4. . 22.2.3.10 Plot the calculated values of voids ratio, or change in volume, against effective pressure to a logarithmic scale (the e/log p’ plot), including the initial voids ratio eo, or initial volume, corresponding to the effective pressure immediate… 22.3 Test report |
| 146 | 23 Determination of permeability Laboratory permeability tests on soils shall be carried out in accordance with BS EN ISO 17892-11 including tests carried out in rigid wall permeameters, oedometer cells and flexible wall permeameters, e.g. tests in triaxial cells, under either consta… 24 Determination of shear strength by the laboratory vane method 24.1 General |
| 147 | 24.2 Apparatus 24.2.1 Laboratory vane apparatus shall consist of the following. (A schematic arrangement is shown in Figure 29.) |
| 149 | 24.2.2 Calibration curve for each torsion spring. 24.2.3 Means of attaching the specimen container or tube to the base of the vane instrument. 24.2.4 Soil trimming tools. 24.2.5 Steel rule, readable to 0.5 mm. 24.2.6 Equipment for the determination of water content, as given in BS EN ISO 17892-1. 24.2.7 Stopclock, readable to 1 s. 24.3 Procedure 24.3.1 Attach the specimen container securely to the base of the vane apparatus, with the sample axis vertical and located centrally under the axis of the vane. 24.3.2 Trim the upper surface of the specimen flat and perpendicular to the axis. 24.3.3 Select a torsion spring that is most appropriate for the estimated strength of the soil and assemble it into the vane apparatus. 24.3.4 Set the pointer and the graduated scale on the torsion head to their zero readings and ensure that there is no backlash in the mechanism for applying torque. 24.3.5 Lower the vane assembly until the end of the vane just touches the surface of the specimen. This provides the datum from which the depth of penetration of the vane can be measured. 24.3.6 Lower the vane assembly further to push the vane steadily into the specimen to the required depth. The top of the vane should be at a distance not less than four times the blade width below the surface. Record the depth of penetration. 24.3.7 Apply torque to the vane by rotating the torsion head at a rate of 6 /min to 12 /min, until the soil has sheared. 24.3.8 Record the maximum angular deflection of the torsion spring and the angle of rotation of the vane at the instant of failure. 24.3.9 If remoulded strength is required, rotate the vane rapidly through two revolutions so as to remould the soil in the sheared zone. 24.3.10 Immediately set the scales to zero as in 24.3.4 and repeat 24.3.7 and 24.3.8 for the soil in the remoulded condition. 24.3.11 Raise the vane steadily. As it emerges from the specimen prevent excessive disturbance due to tearing of the surface. Wipe the blades clean. 24.3.12 Repeat 24.3.4 to 24.3.11 with the vane positioned at two or more additional locations at the same level in the specimen. |
| 150 | 24.3.13 Extrude the specimen from its container and take specimens from the level at which the tests were carried out for determining the soil water content, using the procedure given in BS EN ISO 17892-1. 24.3.14 Record a visual description of the soil at the same level. 24.4 Calculations 24.4.1 For each determination, calculate the torque applied to shear the soil, M(in N mm), by multiplying the maximum angular rotation of the torsion spring (in degrees) by the calibration factor (in N mm per degree). 24.4.2 Calculate the vane shear strength of the soil, (v (in kPa) from the formula: 24.4.3 Calculate the average value of the vane shear strength of the undisturbed soil, v (in kPa). 24.4.4 Calculate the average value of the vane shear strength of the remoulded soil, vr (in kPa). 24.5 Calculate the water content of the soil at the test horizon in accordance with BS EN ISO 17892-1. 24.6 Test report |
| 151 | 25 Determination of shear strength by direct shear (shearbox methods) 25.1 Shearbox methods 25.1.1 Types of test Shear box tests shall be carried out in accordance with BS EN ISO 17892-10. The size of shearbox used shall fulfil the minimum requirement that the largest grain size should not be greater than 1/6 of the specimen height and if particles greater than … 25.1.2 Test conditions The following test conditions shall be specified before a series of tests is started: |
| 152 | 25.2 Determination of shear strength by the small shearbox apparatus 25.2.1 Types of test Small shear box tests shall be carried out under drained conditions in accordance with BS EN ISO 17892-10. Both peak and residual strength determinations may be carried out. 25.2.2 Test report The test report shall state that the test was carried out in accordance with this British Standard, 25.2 and shall include both mandatory and optional reporting in accordance with BS EN 17892-10:2018, 8.1 and 8.2. 25.3 Determination of shear strength by the large shearbox apparatus 25.3.1 Types of test Large shear box tests shall be carried out under drained conditions in accordance with BS EN ISO 17892-10. Both peak and residual strength determinations may be carried out. 25.3.2 Test report The test report shall state that the test was carried out in accordance with this British Standard, 25.3 and shall include both mandatory and optional reporting in accordance with BS EN 17892-10, 8.1 and 8.2. 26 Determination of residual strength using the small ring shear apparatus 26.1 General 26.1.1 Test method The ring shear test shall be carried out in accordance with BS EN ISO 17892-10 which describes two types of ring shear apparatus; Type A and Type B. 26.1.2 Test conditions The following test conditions shall be specified before a series of tests is started: |
| 153 | 26.1.3 Test report The test report shall state that the test was carried out in accordance with this British Standard, Clause 26 and shall include both mandatory and optional reporting in accordance with BS EN 17892-10:2018, 8.1 and 8.2. 27 Determination of the unconfined compressive strength 27.1 General 27.1.1 Test method Unconfined compression tests shall be carried out in accordance with BS EN ISO 17892-7. 27.1.2 Test report 28 Determination of the unconsolidated undrained triaxial test 28.1 Type of test The test shall be carried out in accordance with BS EN ISO 17892-8. The test shall be carried out in the triaxial apparatus on specimens in the form of right cylinders of height approximately equal to twice the diameter. Specimen diameters normally ra… |
| 154 | 28.2 Test conditions The following test conditions shall be specified before starting a series of tests: 28.3 Test report The test report shall state that the test was carried out in accordance with this British Standard, Clause 28 and shall include mandatory reporting in accordance with BS EN 17892-8:2018, 8.1. 29 Consolidated-undrained triaxial compression test with measurement of pore pressure 29.1 Test procedure Consolidated undrained triaxial compression tests with measurement of pore water pressure shall be carried out in accordance with BS EN ISO 17892-9. |
| 155 | 29.2 Test conditions The following test conditions shall be specified before starting a series of tests: 29.3 Test report The test report shall state that the test was carried out in accordance with this British Standard, Clause 29 and shall include mandatory and optional reporting in accordance with BS EN ISO 17892-9:2018, 8.1 to 8.3. 30 Consolidated-drained triaxial compression test with measurement of volume change 30.1 Test procedure Consolidated drained triaxial compression tests shall be carried out in accordance with BS EN ISO 17892-9. The cell pressure shall be maintained constant during the compression stage while the specimen is sheared at a constant rate of axial deformatio… |
| 156 | The volume of pore fluid draining out of or into the specimen shall be measured by means of the volume change indicator in the back pressure line and is equal to the change in volume of the specimen during shear. 30.2 Test conditions The test conditions described in 29.2 shall be specified before starting a series of tests. 30.3 Test report The test report shall state that the test was carried out in accordance with this British Standard, Clause 30 and shall include mandatory and optional reporting in accordance with BS EN ISO 17892-9:2018, 8.1 to 8.3. |
| 157 | Annex A (informative) Example forms |
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