i. Preparation of Specimen from Undisturbed Soil Samples: Clean and weigh the empty containe Cut-off the specimen either from undisturbed tube sample or from block sample, the latte generally being more representative of the field conditions. Remove about 30mm height of so from one end of the soil sample. Gradually insert the consolidation ring in the sample b pressing with hands and carefully removing the material around the ring. The soil specimen s cut shall project as far as 10mm on either side of the ring. Then trim the specimen smooth an flush with the top and bottom of the ring. Wipe the container ring clear of any soil sticking t the outside and weigh again with the soil. The whole process should be quick to ensur minimum loss of moisture and if possible shall be carried out in the moisture room. Th representative specimens from the soil trimming shall be taken in moisture content cans an their moisture content determined in accordance with IS:2720 (Part-XI).
ii. Preparation of Specimen from Disturbed Soil Sample: The soil sample shall be compacted to th desired (field) density and water content in a standard compaction proctor mould. Samples suitable sizes are cut from it as given in Para (i) above.
NOTE-1: Since swelling pressure of the soil is very much influenced by its initial wate content and dry density, it shall be ensured that in the case of undisturbed soil samples, th specimen shall be collected from the field for test during the driest season of the year, s that the swelling pressure recorded shall be maximum. In case of remoulded soil sample the initial water content shall be at the shrinkage limit or field water content, so that th swelling pressure recorded shall be maximum.
NOTE-2: The desiccated soil obtained from the field coupled with smaller thickness consolidation ring make the undisturbed soil specimen always in danger of being disturbe during trimming; hence great care shall be taken to handle the specimen delicately with th least pressure applied to the soil.
iii. Saturate the porous stones by boiling in distilled water for at least 15 minutes and moisten a surfaces of the consolidometer which are to be enclosed. Assemble the consolidometer with th soil specimen (in the ring) and porous stones at top and bottom of the specimen, providing wet filter paper between the soil specimen and the porous stone. Then position the loadin block centrally on the top porous stone.
iv. Mount this assembly on the loading frame such that load applied is transmitted to the so specimen through the loading cap.v. In the case of the lever loading system, the apparatus shall be properly counter-balanced. If jack with load measurements by platform scales is used as the loading systems the tare weigh with the empty consolidation apparatus, excluding those parts which will be on top of the so specimen, which rest on the platform shall be determined before filling the ring with the soil an this tare weight shall be added to the computed scale loads required to give the desire pressures at the time of loading the soil specimen.
vi. Screw the holder with the dial gauge to record the progressive vertical heave of the specime under no load
vii. Place initial setting load of 50 gf/cm2 (this includes weight of the porous stone and the loadin pad) on the loading hanger and note initial reading of the dial gauge. Fig. 2: Swell Pressure Test by Constant Volume Method The arrangement for Swell Pressure Test by Constant Volume Method consists of Loading unit (5 tonnes), Proving ring (with high sensitivity, 200 kg capacity) along with all Apparatus as used in Consolidometer method.
viii. Connect the system to a water reservoir with the level of water in the reservoir being at abou the same level as the soil specimen and allow water to flow in the sample. Then allow the soil t swell.
ix. Record the free swell readings shown by the dial gauge under the seating load at different tim intervals. The dial gauge readings shall be taken till equilibrium is reached. This is ensured b making a plot of swelling dial reading versus time in hours, which plot becomes asymptotic wit abscissa (time scale). The equilibrium swelling is normally reached over a period of 6 to 7 day in general for all expansive soils.
x. Then subject the swollen sample to consolidation under different pressures. Record th compression dial readings till the dial readings attain a steady state for each load applied ove the specimen. The consolidation loads shall be applied till the specimen attains its origin volume.
i. Preparation of Specimen from Undisturbed Soil Samples as well as Preparation of Specime from Disturbed Soil Sample: Same as for “Consolidometer Method”.
ii. Keep the consolidation specimen ring with the specimen between two porous stones saturate in boiling water providing a filter paper between the soil specimen and the porous stone. Th loading block shall then be positioned centrally on the top of the porous stone.
iii. Then place this assembly on the platen of the loading unit. The load measuring proving ring t attached to the load frame shall be placed in contact with the consolidation cell without an eccentricity. A direct strain measuring dial gauge shall be fitted to the cell. Inundate th specimen with distilled water and allow it to swell.
iv. Note down the initial reading of the proving ring. The swelling of the specimen with increasin volume shall be obtained in the strain measuring load gauge. To keep the specimen at constan volume, the platen shall be so adjusted that the dial gauge always show the original reading This adjustment shall be done at every 1 mm of swell or earlier. The duration of test sha conform to the requirements given in “Consolidometer method”. Then dismantle the assemb and extract the soil specimen from the consolidation ring to determine final moisture content accordance with IS: 2720 (Part-IX).