Standard Test Methods for One-Dimensional Swell or Settlement Potential of Cohesive Soils 1

Transcription

1 Designation: 96 AMERICAN SOCIETY FOR TESTING AND MATERIALS 100 Barr Harbor Dr., West Consoocken, PA Reprinted from te Annual Book of ASTM Standards. Copyrigt ASTM Standard Test Metods for One-Dimensional Swell or Settlement Potential of Coesive Soils 1 Tis standard is issued under te fixed designation ; te number immediately following te designation indicates te year of original adoption or, in te case of revision, te year of last revision. A number in parenteses indicates te year of last reapproval. A superscript epsilon (e) indicates an editorial cange since te last revision or reapproval. 1. Scope * 1.1 Tese test metods cover tree alternative laboratory metods for determining te magnitude of swell or settlement of relatively undisturbed or compacted coesive soil. NOTE 1 Refer to Section 5 to determine te best metod for a particular application. 1.2 Te test metods can be used to determine (a) te magnitude of swell or settlement under known vertical (axial) pressure, or (b) te magnitude of vertical pressure needed to maintain no volume cange of laterally constrained, axially loaded specimens. 1.3 Te values stated in SI units are to be regarded as te standard. Te values stated in inc-pound units are approximate. 1.4 Tis standard does not purport to address all of te safety concerns, if any, associated wit its use. It is te responsibility of te user of tis standard to establis appropriate safety and ealt practices and determine te applicability of regulatory limitations prior to use. 2. Referenced Documents 2.1 ASTM Standards: D 422 Test Metod for Particle-Size Analysis of Soils 2 D 653 Terminology Relating to Soil, Rock, and Contained Fluids 2 D 698 Test Metod for Laboratory Compaction Caracteristics of Soil Using Standard Effort ( ft-lbf/ft 3 (600 kn-m/m 3 )) 2 D 854 Test Metod for Specific Gravity of Soils 2 D 1557 Test Metod for Laboratory Compaction Caracteristics of Soils Using Modified Effort ( ft-lbf/ft 3 (2.700 kn-m/m 3 )) 2 D 1587 Practice for Tin-Walled Tube Sampling of Soils 2 D 2216 Test Metod for Laboratory Determination of Water (Moisture) Content of Soil and Rock 2 D 2435 Test Metod for One-Dimensional Consolidation Properties of Soils 2 1 Tese test metods are under te jurisdiction of ASTM Committee D-18 on Soil and Rock and are te direct responsibility of Subcommittee D18.05 on Structural Properties of Soils. Current edition approved May 10, Publised December Originally publised as 85. Last previous edition Annual Book of ASTM Standards, Vol D 3550 Practice for Ring-Lined Barrel Sampling of Soils 2 D 3740 Practice for Minimum Requirements for Agencies Engaged In te Testing and/or Inspection of Soil and Rock as Used In Engineering Design and Construction 2 D 3877 Test Metods for One-Dimensional Expansion, Srinkage, and Uplift Pressure of Soil-Lime Mixtures 2 D 4220 Practices for Preserving and Transporting Soil Samples 2 D 4318 Test Metod for Liquid Limit, Plastic Limit, and Plasticity Index of Soils 2 3. Terminology 3.1 Definitions Refer to Terminology D 653 for standard definitions of terms. 3.2 Definitions of Terms Specific to Tis Standard: eave (L) increase in vertical eigt, D, of a column of in situ soil of eigt following sorption of water percent eave or settlement, % increase or decrease in te ratio of te cange in vertical eigt, D, to te original eigt of a column of in situ soil; or D / settlement, L decrease in vertical eigt, D, of a column of in situ soil of eigt swell, L increase in elevation or dilation of soil column following sorption of water free swell, % percent eave, D / 3 100, following sorption of water at te seating pressure s se primary swell, L an arbitrary sort-term swell usually caracterized as being completed at te intersection of te tangent of reverse curvature to te curve of a dimensional cange-logaritm of time plot wit te tangent to te straigt line portion representing long-term or secondary swell (Fig. 1) secondary swell, L an arbitrary long-term swell usually caracterized as te linear portion of a dimensional cange-logaritm of time plot following completion of sortterm or primary swell (Fig. 1) swell index slope of te rebound pressure - void ratio curve on a semi-log plot swell pressure, FL 2 (1) a pressure wic prevents te specimen from swelling as obtained in Metod C, or (2) tat pressure wic is required to return te specimen back to its original state (void ratio, eigt) after swelling in Metod A or B. NOTE 2 Swell pressures by Metod C corrected for specimen disturbance may be similar to or sligtly greater tan tose by Metod A. *A Summary of Canges section appears at te end of tis standard. 1

2 FIG. 1 Time - Swell Curve 4. Summary of Test Metods 4.1 Te following tree alternative test metods require tat a soil specimen be restrained laterally and loaded axially in a consolidometer wit access to free water Metod A Te specimen is inundated and allowed to swell vertically at te seating pressure (pressure of at least 1 kpa (20 lbf/ft 2 ) applied by te weigt of te top porous stone and load plate) until primary swell is complete. Te specimen is loaded after primary swell as occurred until its initial void ratio/eigt is obtained Metod B A vertical pressure exceeding te seating pressure is applied to te specimen before placement of free water into te consolidometer. Te magnitude of vertical pressure is usually equivalent to te in situ vertical overburden pressure or structural loading, or bot, but may vary depending on application of te test results. Te specimen is given access to free water. Tis may result in swell, swell ten contraction, contraction, or contraction ten swell. Te amount of swell or settlement is measured at te applied pressure after movement is negligible Metod C Te specimen is maintained at constant eigt by adjustments in vertical pressure after te specimen is inundated in free water to obtain swell pressure. A consolidation test is subsequently performed in accordance wit Test Metod D Rebound data is used to estimate potential eave. 5. Significance and Use 5.1 Te relative swell/settlement potential of soil determined from tese test metods can be used to develop estimates of eave or settlement for given final moisture and loading conditions. Te initial water content and void ratio sould be representative of te in situ soil immediately prior to construction. Selection of test metod, loading, and inundation sequences sould, as closely as possible, simulate any construction and post-construction wetting and drying effects and canges in loading conditions. 5.2 Soils containing montmorillonites (Smectite) are likely to ave a significant potential for swell and are commonly tested by tese test metods. NOTE 3 Montmorillonites wit divalent cations usually swell less tan wit monovalent cations. It is useful to know te type of cation as well as te cation excange capacity of montmorillonite. 5.3 Laboratory-prepared test specimens sould duplicate te in situ soil or field-compacted soil conditions as closely as possible because relatively small variations in unit weigt and water content can significantly alter te measured eave and swell pressure. Differences in soil fabric of te compacted specimens, suc as obtained by kneading or static compaction, could also ave a significant impact on te swell/settlement beavior of coesive soils. 5.4 Tese test metods are applicable to undisturbed test or remolded specimens, or bot, as follows: Metod A Tis test metod measures (a) te free swell, (b) percent eave for vertical confining pressures up to te swell pressure, and (c) te swell pressure Metod B Tis test metod measures (a) te percent eave or settlement for vertical pressure usually equivalent to te estimated in situ vertical overburden and oter vertical pressure up to te swell pressure, and (b) te swell pressure Metod C Tis test metod measures (a) te swell pressure, (b) preconsolidation pressure, and (c) percent eave or settlement witin te range of applied vertical pressures. NOTE 4 Metods A and C ave produced estimates of eave consistent wit observed eave. Metod B may lead to estimates of eave less tan observed eave. Metod A as not been recommended for evaluation of swell pressure and consolidation parameters for settlement estimates because sorption of water under practically no restraint may disturb te soil structure. NOTE 5 Notwitstanding te statement on precision and bias contained in tis standard: Te precision of tis test metod is dependent on te competence of te personnel performing te test and te suitability of te equipment and facilities used. Agencies wic meet te criteria of Practice D 3740 are generally considered capable of competent and objective testing. Users of tis test metod are cautioned tat compliance wit Practice D 3740 does not in itself assure reliable testing. Reliable testing depends on several factors; Practice D 3740 provides a means of evaluating some of tese factors. 6. Interferences 6.1 Estimates of te swell and settlement of soil determined by tese test metods are often of key importance in design of floor slabs on grade and evaluation of teir performance. However, wen using tese estimates it is recognized tat swell parameters determined from tese test metods for te purpose of estimating in situ eave of foundations and compacted soils may not be representative of many field conditions because: Lateral swell and lateral confining pressure are not simulated Swell in te field usually occurs under constant overburden pressure, depending on te availability of water. Swell in te laboratory is evaluated by observing canges in volume due to canges in applied pressure wile te specimen is inundated wit water. Metod B is designed to avoid tis limitation Rates of swell indicated by swell tests are not always reliable indicators of field rates of eave due to fissures in te in situ soil mass and inadequate simulation of te actual availability of water to te soil. Te actual availability of water to te foundation may be cyclic, intermittent, or depend on in-place situations, suc as pervious soil-filled trences and broken water and drain lines Secondary or long-term swell may be significant for 2

3 some soils and sould be added to primary swell Cemical content of te inundating water affects volume canges and swell pressure; tat is, field water containing large concentrations of calcium ions will produce less swelling tan field water containing large concentrations of sodium ions or even rain water Disturbance of naturally occurring soil samples greatly diminises te meaningfulness of te results. 7. Apparatus and Materials 7.1 Consolidometer Te apparatus sall comply wit te requirements of Test Metod D Te apparatus sall be capable of exerting a pressure on te specimen of (1) at least 200 % of te maximum anticipated design pressure, or (2) te pressure required to maintain te original specimen eigt wen te specimen is inundated (Metod C), wicever is greatest Consolidometer rigidity influences te observed swell, particularly wit Metod C. Terefore, consolidometers of ig rigidity sould be used wit Metod C (see Test Metod D 2435). NOTE 6 Small increases in soil volume can significantly relieve swell pressures. Terefore, variations in displacements tat occur during determination of swell pressures by Metod C sould be as small as possible to reduce te magnitude of correction required in Te measurements, especially swell pressure measurements, sould be based on corrections for compression of members. 7.2 Porous Stones Te stones sall be smoot ground and fine enoug to minimize intrusion of soil into te stones if filter paper is not used and sall reduce false displacements caused by seating of te specimen against te surface of porous stones (Note 7). Suc displacements may be significant, especially if displacements and applied vertical pressures are small Porous stones sall be air dry Porous stones sall fit close to te consolidometer ring to avoid extrusion or puncing at ig vertical pressures. Suitable stone dimensions are described in 5.3 of Test Metod D NOTE 7 A suitable pore size is 10 µm if filter paper is not used. Filter paper is not recommended because of its ig compressibility and sould not be used wen measuring te swell/settlement of stiff clays and wen measuring swell pressure by Metod C. 7.3 Plastic Membrane, Aluminum Foil, or Moist Paper Towel, a loose fitting cover to enclose te specimen, ring, and porous stones prior to inundating te specimen, used to minimize evaporation from te specimen. 8. Sampling of Naturally Occurring Soils 8.1 Disturbance of te soil sample from wic specimens are to be obtained greatly diminises te meaningfulness of results and sould be minimized. Practice D 1587 and Practice D 3550 cover procedures and apparatus tat may be used to obtain satisfactory undisturbed samples. 8.2 Storage in sampling tubes is not recommended for swelling soils even toug stress relief may be minimal. Te influence of rust and penetration of drilling fluid or free water into te sample may adversely influence laboratory test results. Water and oxygen from te sample could cause te formation of rust witin te tube wic could result in te sample adering to te tube. Terefore, sampling tubes sould be brass, stainless steel, or galvanized or lacquered inside to inibit corrosion in accordance wit Practice D If samples are to be stored prior to testing, tey sould be extruded from te sampling tubes as quickly as possible after sampling and torougly sealed to minimize furter stress relief and moisture loss. Te sample sould be extruded from te sampling tube in te same direction as sampled, to minimize furter sample disturbance. If te sample cannot be extruded from te tubes immediately, tey sould be andled and sipped in accordance wit Practices D 4220, Group D. 8.4 Prior to sealing in storage containers, samples extruded from tubes tat were obtained wit slurry drilling tecniques sould be wiped clean to remove drilling fluid adering to te surface of te sample. An outer layer of 3 to 6 mm (0.1 to 0.3 in.) sould be trimmed from te cylindrical surface of te samples so tat moisture or te slurry will not penetrate into te sample and alter te swell potential, swell pressure, and oter soil parameters. Suc trimming will also remove some disturbance at te peripery due to sidewall friction. Drilling wit air or foam instead of slurry will reduce moisture penetration. 8.5 Containers for storage of extruded samples may be eiter cardboard or metal and sould be approximately 25 mm (1 in.) greater in diameter and 40 to 50 mm (1.5 to 2.0 in.) greater in lengt tan te sample to be encased. 8.6 Soil samples stored in containers sould be completely sealed in wax. Te temperature of te wax sould be 8 to 14 C (15 to 25 F) above te melting point wen applied to te soil sample; wax tat is too ot will penetrate pores and cracks in te sample and render it useless and will also dry te sample. Aluminum foil, ceese clot, or plastic wrap may be placed around te sample to prevent penetration of molten wax into open fissures. A small amount of wax (about 113-mm or 0.5-in. tickness) sould be placed in te bottom of te container and allowed to partly congeal. Te sample sould subsequently be placed in te container, completely immersed and covered wit molten wax, and ten allowed to cool before moving. NOTE 8 A good wax for sealing expansive soils consists of a1to1 mixture of paraffin and microcrystalline wax or 100 % beeswax. 8.7 Examine and test samples as soon as possible after receipt; owever, samples required to be stored sould be kept in a umid room and may require rewaxing and relabeling before storage. Samples encased in wax or sampling tubes may be cut using a band-saw. Te soil specimen sould be adequately supported wile trimming to size using sarp and clean instruments. Te specimen may be extruded from a section of sampling tube and trimmed in one continuous operation to minimize sampling disturbance. 9. Specimen Preparation 9.1 Undisturbed or laboratory-compacted specimens may be used for testing. Prepare laboratory-compacted specimens to duplicate compacted fills as closely as possible. NOTE 9 Te compaction metod, suc as kneading or static compaction, may influence te volume cange beavior wen prepared wet of optimum water content. Compaction of laboratory specimens is described in Test Metods D 698 and Test Metods D Swelling soil is 3

4 sometimes adequately treated wit lime and test specimens compacted as described in Test Metods D Trim te specimen in accordance wit Test Metod D A ring extension or guide ring as sown in Test Metods D 3877 may be added to te consolidometer assembly to accommodate specimen swell. Alternatively, a tin ard disk may be inserted in te bottom of te specimen ring during compaction or trimming of a specimen into te ring. Turn te ring and specimen upside down and remove te tin disk insert to provide space for specimen swell. Take precaution to minimize disturbance of te soil or canges in moisture and unit weigt during sample transportation and preparation. Vibration, distortion, and compression must be avoided. NOTE 10 Tests wit specimens recessed 5 mm (0.2 in.) in rings of 25-mm (1.0-in.) eigt ave performed adequately. 10. Calibration 10.1 Calibrate te consolidation macine in accordance wit Test Metod D Measure te compressibility of te apparatus wit a smoot copper, brass, or ard steel disk substituted for te soil specimen. Te disk sould be approximately te same eigt as te specimen and 1 mm (0.04 in.) smaller in diameter tan tat of te ring. Place moistened filter papers between te porous stones and metal disk if filter papers are to be used during te test. Allow sufficient time for moisture to be squeezed from te filter paper during eac load increment and decrement. Te deflections of te calibration test are subtracted from te deflections of te soil test for eac load increment and decrement. NOTE 11 Wen filter paper is used, calibration must duplicate te exact load increment/decrement sequence due to inelastic compression of paper; tus, calibration is needed for eac test. Periodic calibration will suffice for tests witout filter paper. 11. Associated Soil Properties 11.1 Determine te initial (or natural) water content, wet and dry unit weigts, volume, and initial void ratio in accordance wit Test Metod D Determine te specific gravity in accordance wit Test Metod D 854 wen results are required in terms of void ratio. Te liquid limit, plastic limit, and plasticity index as determined in accordance wit Test Metod D 4318 and te particle size distribution for soils wit substantial granular material as determined in accordance wit Metod D 422 are useful in identifying te soil and correlating results of tests on different soils. 12. Procedure 12.1 Assemble te ring wit te specimen recessed in te ring, dry filter paper if used, and air-dry porous stones in te loading device. Enclose te specimen, ring, filter paper, if any, and porous stones as soon as possible wit a loose fitting plastic membrane, moist paper towel, or aluminum foil to minimize cange in specimen water content and volume due to evaporation. Tis wrapping may be cut away and discarded at te time of specimen inundation Apply a seating pressure, s se, of at least 1 kpa (20 lbf/ft 2 ). Witin 5 min after application of s se, adjust te extensometer deformation device for te initial or zero reading A grapical representation of results of te tree alternative test metods sown in Fig. 2 includes corrections for consolidometer compressibility. Tese test metods are performed in accordance wit Test Metod D 2435 except as follows: Metod A After te initial deformation reading at te seating pressure is recorded, inundate te specimen and record deformations after various elapsed times. Readings at 0.1, 0.2, 0.5, 1.0, 2.0, 4.0, 8.0, 15.0, and 30.0 min and 1, 2, 4, 8, 24, 48, and 72 are usually satisfactory. Continue readings until primary swell is complete, as determined by te metod illustrated in Fig. 1. After completion of swell, apply a vertical pressure of approximately 5, 10, 20, 40, 80, etc., kpa (100, 200, 400, 800, 1600, etc., lbf/ft 2 ) wit eac pressure maintained constant in accordance wit 10.4 of Test Metod D Maintain pressure until te specimen is recompressed to its initial void ratio/eigt. Te duration of eac load increment sall be equal and of a duration wic assures 100 % primary consolidation (see section 11.2 or 11.6 of Test Metod D 2435). NOTE 12 Some secondary swell must be recorded in order to determine grapically te end of primary swell. NOTE 13 Te duration of a typical loading increment is 1 day. NOTE 14 Vertical pressures may be applied to recompress te specimen to void ratios less tan te initial void ratio (point 6, Fig. 2 (Metod A)) because te exact magnitude of vertical pressure required to recompress te specimen to its initial void ratio is unknown. Loading units equipped wit pneumatic regulators are ideally suited for tis purpose Metod A may be modified to place an initial vertical stress, s 1, on te specimen equivalent to te estimated vertical pressure on te in situ soil witin 5 min of placing te seating pressure and securing te zero deformation reading. Read te deformation witin 5 min and remove te vertical stress, except for te seating pressure. Record te deformation witin 5 min after removal of s 1, inundate te specimen, and continue te test as in Tis modification provides a correction to te initial deformation reading at s se in an effort to more closely duplicate te in situ void ratio of te soil Metod B Apply a vertical pressure exceeding te seating pressure witin 5 min of placing te seating pressure. Read te deformation witin 5 min of placing te vertical pressure. Te specimen is inundated immediately after te deformation is read and deformation recorded after elapsed times similar to until primary swell is complete. Continue te test as in Metod C Apply an initial stress, s 1, equivalent to te estimated vertical in situ pressure or swell pressure witin 5 min after placement of te seating pressure. Read te deformation witin 5 min after placing s 1, and immediately inundate te specimen wit water. Apply increments of vertical stress as needed to prevent swell (see Note 14). Variations from te deformation reading at te time te specimen is inundated at stress s 1 sall be kept preferably witin mm ( in.) and not more tan mm ( in.). Load te specimen in accordance wit , following no furter tendency to swell (usually overnigt). Load increments sall be sufficient to define te maximum point of curvature on te consolidation curve and to determine te slope of te virgin compression curve. Te rebound curve following consolidation sall also be determined as illustrated in Fig. 2 (Metod C). 4

5 FIG. 2 Void Ratio - Log Pressure Curves Duration of rebound load decrements sall be in accordance wit 10.6 of Test Metod D NOTE 15 Te use of small weigt increments, suc as lead sot, provide adequate control as needed to prevent swell Measurements sall include te time of reading, applied stress, observed deformation, and corrections for compression of members. 13. Calculation 13.1 Compute te initial void ratio or eigt, water content, wet and dry unit weigts, and degree of saturation in accordance wit Test Metod D Te void ratio or percent eave calculations are based on te final dial reading for eac swell increment and load increment or decrement. Te void ratio or percent eave may be plotted versus logaritm of te vertical pressure, as for examples of te tree metods grapically illustrated in Fig. 2. Te percent eave sall be relative to an initial specimen eigt, o, observed for an appropriate applied vertical pressure, s (see 4.1.2). Void ratio or percent eave versus vertical pressure on an aritmetic scale may also be useful for practical applications Te data points from a plot of e versus log 10 s (Fig. 2) may be used to evaluate te swell and settlement parameters of te tested soil Metod A Te free swell at te seating pressure relative to te initial void ratio, e o, is given as follows (see Fig. 2 (Metod A)): D o e se 2 e o 1 1 e o S g do g dse 2 1D 100 (1) were: D 5 cange in specimen eigt, o 5 initial specimen eigt, e se 5 void ratio after stabilized swell at te seating pressure s se, e o 5 initial void ratio, g do 5 dry unit weigt at void ratio e o, and g dse 5 dry unit weigt at void ratio e se. NOTE 16 Fig. 2 (Metod A) illustrates te free swell at a seating pressure s se 5 1 kpa (20 lbf/ft 2 ). D % (2) Te percent eave of 6.9 % may be read directly from te rigt ordinate of Fig. 2 (Metod A) for e se , point 4. 5

6 Te percent eave at a vertical pressure, s, up to te swell pressure s sp, relative to e o or an appropriate initial vertical pressure s vo, is as follows (see Fig. 2 (Metod A)): D o e 2 e o 1 1 e o S g do g d 2 1D 100 (3) were: e 5 void ratio at vertical pressure, and g d 5 dry unit weigt at void ratio e. NOTE 17 Fig. 2 (Metod A) illustrates a percent eave, as follows: D % were: e 5 e vo , and s 5 s vo kpa (2000 lbf/ft 2 ). Te swell pressure, s sp, is given by 400 kpa (8350 lbf/ft 2 ) relative to e o Fig. 2 may be plotted wit dry unit weigt, g d, versus logaritm of applied pressure, s, instead of void ratio e versus logaritm s if specific gravities were not determined. Te swell for any cange in dry unit weigt witin limits of te test results may be determined in a manner similar to tat described in Metod B Te percent eave at te vertical pressure s vo, applied following te seating pressure, (see 4.1.2) relative to e o is given as follows (see Fig. 2 (Metod B)): D o e vo 2 e o 1 1 e o S g do g dvo 2 1 D 100 (4) were: e vo 5 void ratio after stabilized swell at te applied vertical pressure s vo, and g dvo 5 unit dry weigt at void ratio e vo. NOTE 18 Fig. 2 (Metod B) illustrates a percent eave, as follows: D % were: s5s vo kpa (2000 lbf/ft 2 ), and s sp 5 swell pressure kpa (7300 lbf/ft 2 ) for e o Computations of settlement are similar if te specimen contracts at te applied vertical pressure following access to water Metod C Te swell pressure s sp (point 3, Fig. 2 (Metod C)) sall be corrected upward by a suitable construction procedure. Soil disturbance and te process of adjusting vertical pressures may allow some volume expansion to occur, wic reduces te maximum observed swell pressure. NOTE 19 Suitable correction procedures include tose based on te preconsolidation pressure s vm. A construction procedure for soils tat break onto a virgin compression curve wen te recompression curve is not apparent is as follows: (a) locate te point of maximum curvature (point 5, Fig. 2 (Metod C)), (b) draw orizontal, tangential, and bisector lines troug te point of maximum curvature, (c) draw te virgin part of te compression curve backward to intersect te bisector at te preconsolidation pressure s vm, or 780 kpa (Fig. 2 (Metod C)). Te swell pressure is taken as te preconsolidation pressure. Te slope of te rebound curve of tese soils is usually muc less tan tat of te compression curve. NOTE 20 A modified construction procedure may be used for soils tat break onto te recompression curve, Fig. 2 (Metod C). Te construction procedure is as follows: (a) locate te point of maximum curvature (point 4, Fig. 2 (Metod C)), (b) draw orizontal, tangential, and bisector lines troug te point of maximum curvature, (c) extend te recompression line troug te bisector line. Intersection of te recompression line wit te bisector line is designated te corrected swell pressure, s8 sp, wic is 380 kpa for te example in Fig. 2 (Metod C). A detail of tis construction is sown in Fig. 3. s8 sp in tis case is less tan s vm. If te recompression line is not well defined, draw a line parallel wit te rebound curve for void ratios greater tan e o troug te bisector line. Frequent load increments may be necessary to define any recompression curve Draw a suitable curve parallel wit te rebound (or recompression) curve for void ratios greater tan e o troug te corrected swell pressure s8 sp at te initial void ratio e o given by point 3, Fig. 2 (Metod C), to obtain te percent eave for any vertical pressure relative to s8 sp and e o witin te range of test results. NOTE 21 Percent eave calculated by Metod C for s vo kpa (2000 lbf/ft 2 ) is as follows: D e vo 2 e o o 1 1 e 2.4 % Te percent settlement (negative percent eave) may be evaluated from te void ratio e 2 exceeding te corrected swell pressure, as follows: D e 2 2 e o o 1 1 e (5) o NOTE 22 Fig. 2 (Metod C) illustrates te percent settlement, as follows: D % were: e , and s kpa ( lbf/ft 2 ). 14. Report 14.1 Te report sall include te information required in Test Metod D 2435, and sall also include te following: All departures from procedures, including canges in loading sequences Te percent eave or settlement for te given vertical pressure and swell pressure s sp, or corrected swell pressure s8 s p. Te compression index, C c, and swell index, C s, sould be reported if tese are evaluated. All departures from te described procedures for computing tese parameters and correction procedures used to determine percent eave or settlement FIG. 3 Construction Detail for Metod C 6

7 and s8 sp sall be described Te type of water used to inundate te specimen. 15. Precision and Bias 15.1 Precision Data are being evaluated to determine te precision of tis test metod. In addition, Subcommittee D18.05 is seeking pertinent data from users of te test metod Bias Tere is no accepted reference value for tis test metod, terefore, bias cannot be determined. 16. Keywords 16.1 Expansive soil; eave; laboratory tests; settlement; swell pressure; swell index. SUMMARY OF CHANGES Tis section identifies location of canges to tese test metods since te last edition. (1) Standard Practice D 3740 was added to Section 2, Referenced Documents. (2) A new Note 5 was inserted in Section 5, Significance and Use, immediately after Note 4. (3) Te remaining Notes 5-21 were renumbered. (4) A new Section entitled Summary of Canges was added. Te American Society for Testing and Materials takes no position respecting te validity of any patent rigts asserted in connection wit any item mentioned in tis standard. Users of tis standard are expressly advised tat determination of te validity of any suc patent rigts, and te risk of infringement of suc rigts, are entirely teir own responsibility. Tis standard is subject to revision at any time by te responsible tecnical committee and must be reviewed every five years and if not revised, eiter reapproved or witdrawn. Your comments are invited eiter for revision of tis standard or for additional standards and sould be addressed to ASTM Headquarters. Your comments will receive careful consideration at a meeting of te responsible tecnical committee, wic you may attend. If you feel tat your comments ave not received a fair earing you sould make your views known to te ASTM Committee on Standards, 100 Barr Harbor Drive, West Consoocken, PA