ASTM_D_4546_-_21.pdf

Designation:D454621Standard Test Methods forOne-Dimensional Swell or Collapse of Soils1This standard is issued under the fixed designation D4546;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope*1.1 This standard covers two laboratory test methods formeasuring the magnitude of one-dimensional wetting-inducedswell or collapse of unsaturated soils and one method formeasuring load-induced compression subsequent to wetting-induced deformation.1.1.1 Test Method A is a procedure for measuring one-dimensional wetting-induced swell or hydrocompression(col-lapse)of reconstituted specimens simulating field condition ofcompacted fills.The magnitude of swell pressure(the mini-mum vertical stress required to prevent swelling),and freeswell(percent swell under a pressure of 1 kPa or 20 lbf/ft2)canalso be determined from the results of Test Method A.1.1.2 Test Method B is a procedure for measuring one-dimensional wetting-induced swell or collapse deformation ofintact specimens obtained from a natural deposit or from anexisting compacted fill.The magnitude of swell pressure andfree swell can also be determined from the results of TestMethod B.1.1.3 Test Method C is a procedure for measuring load-induced strains on a reconstituted or intact specimen after thespecimen has undergone wetting-induced swell or collapsedeformation.1.2 In Test Method A,a series of reconstituted specimensduplicating compaction condition of the fine fraction of the soilin the field(excluding the oversize particles)are assembled inconsolidometer units.Different loads corresponding to differ-ent fill depths are applied to different specimens and eachspecimen is given access to free water until the process ofprimary swell or collapse is completed(Fig.1)under aconstant vertical total stress(Fig.2).The resulting swell orcollapse deformations are measured.This test method can bereferred to as wetting-after-loading tests on multiple reconsti-tuted specimens.The data from these tests can be used toestimate one-dimensional ground surface heave or settlementthat can occur due to full wetting after fill construction.Inaddition,the magnitude of swell pressure and the magnitude offree swell can be interpreted from the test results.1.3 Test Method B is commonly used for measuring one-dimensional wetting-induced swell or hydrocompression ofindividual intact samples.This method can be referred to assingle-point wetting-after-loading test.The vertical pressure atwetting for the specimen is chosen equal to the vertical in-situstress(overburden stress plus structural stress,if any)corre-sponding to the sampling depth.The test result indicates theamount of heave or hydrocompression that can result when thesoil at a given fill depth is wetted from the current moisturecondition to full inundation condition.If intact specimens fromvarious depths are tested,the swell or collapse strain data canbe used to estimate heave or settlement of the ground surface.If the objective of the test is to measure swell pressure for anexpansive soil,a series of intact specimens from a given depthzone can be wetted under a range of pressures(similar to TestMethod A)and the results interpreted to determine the magni-tude of the swell pressure.1.4 Test Method C is for measuring load-induced strainsafter wetting-induced swell or collapse deformation has oc-curred.This method can be referred to as loading-after-wettingtest.The test can be performed on either intact or reconstitutedspecimens,and can be on one specimen or a series ofspecimens.The results would apply to situations where newfill,additional structural loads,or both,are applied to theground that has previously gone through wetting-inducedheave or settlement.The first part of the test is the same as inTest Method A or B.After completion of the swell or collapseunder a given vertical load,additional vertical load incrementsare applied to the specimen in the same manner as in aconsolidation test(Test Methods D2435/D2435M)and theload-induced strains are measured.1.5 It shall be the responsibility of the agency requestingthis test to specify the magnitude of each load for Test MethodA and Test Method B.For Test Method C,the agencyrequesting the test should specify the magnitude of the stressunder which the specimen is wetted,and the magnitudes of theadditional stress increments subsequent to wetting.1.6 These test methods do not address the measurement ofsoil suction and suction-controlled swell-collapse tests.Theaddition of suction-controlled wetting does not constitutenonconformance to these test methods.1These test methods are under the jurisdiction ofASTM Committee D18 on Soiland Rock and are the direct responsibility of Subcommittee D18.05 on Strength andCompressibility of Soils.Current e