ASTM_D_2435_-_D_2435M_-_11_2020.pdf

Designation:D2435/D2435M11(Reapproved 2020)Standard Test Methods forOne-Dimensional Consolidation Properties of Soils UsingIncremental Loading1This standard is issued under the fixed designation D2435/D2435M;the number immediately following the designation indicates theyear of original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of lastreapproval.A superscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 These test methods cover procedures for determiningthe magnitude and rate of consolidation of soil when it isrestrained laterally and drained axially while subjected toincrementally applied controlled-stress loading.Two alterna-tive procedures are provided as follows:1.1.1 Test Method AThis test method is performed withconstant load increment duration of 24 h,or multiples thereof.Time-deformation readings are required on a minimum of twoload increments.This test method provides only the compres-sion curve of the specimen and the results combine bothprimary consolidation and secondary compression deforma-tions.1.1.2 Test Method BTime-deformation readings are re-quired on all load increments.Successive load increments areapplied after 100%primary consolidation is reached,or atconstant time increments as described in Test Method A.Thistest method provides the compression curve with explicit datato account for secondary compression,the coefficient ofconsolidation for saturated materials,and the rate of secondarycompression.NOTE1The determination of the rate and magnitude of consolidationof soil when it is subjected to controlled-strain loading is covered by TestMethod D4186/D4186M.1.2 These test methods are most commonly performed onsaturated intact samples of fine grained soils naturally sedi-mented in water,however,the basic test procedure isapplicable,as well,to specimens of compacted soils and intactsamples of soils formed by other processes such as weatheringor chemical alteration.Evaluation techniques specified in thesetest methods assume the pore space is fully saturated and aregenerally applicable to soils naturally sedimented in water.Tests performed on other unsaturated materials such as com-pacted and residual(weathered or chemically altered)soilsmay require special evaluation techniques.In particular,therate of consolidation(interpretation of the time curves)is onlyapplicable to fully saturated specimens.1.3 It shall be the responsibility of the agency requestingthis test to specify the magnitude and sequence of each loadincrement,including the location of a rebound cycle,ifrequired,and,for Test Method A,the load increments forwhich time-deformation readings are desired.The requiredmaximum stress level depends on the purpose of the test andmust be agreed on with the requesting agency.In the absenceof specific instructions,Section 11 provides the default loadincrement and load duration schedule for a standard test.NOTE2Time-deformation readings are required to determine the timefor completion of primary consolidation and for evaluating the coefficientof consolidation,cv.Since cvvaries with stress level and loading type(loading or unloading),the load increments with timed readings must beselected with specific reference to the individual project.Alternatively,therequesting agency may specify Test Method B wherein the time-deformation readings are taken on all load increments.1.4 These test methods do not address the use of a backpressure to saturate the specimen.Equipment is available toperform consolidation tests using back pressure saturation.Theaddition of back pressure saturation does not constitute non-conformance to these test methods.1.5 UnitsThe values stated in either SI units or inch-pound units given in brackets are to be regarded separately asstandard.The values stated in each system may not be exactequivalents;therefore,each system shall be used independentlyof the other.Combining values from the two systems mayresult in non-conformance with the standard.1.5.1 In the engineering profession it is customary practiceto use,interchangeably,units representing both mass and force,unless dynamic calculations(F=Ma)are involved.This im-plicitly combines two separate systems of units,that is,theabsolute system and the gravimetric system.It is scientificallyundesirable to combine two separate systems within a singlestandard.This test method has been written using SI units;however,inch-pound conversions are given in the gravimetricsystem,where the pound(lbf)represents a unit of force(weight).The use of balances or scales recording pounds ofmass(lbm),or the recording of density in lb/ft3should not beregarded as nonconformance with this test method.1These test methods are under the jurisdiction ofASTM Committee D18 on Soiland Rock and is the direct responsibility of Subcommittee D18.05 on Strength andCompressibility of Soils.Current edition approved April 1,2020.Published April 2020.Originallyapprove