ASTM D5918-2006 Standard Test Methods for Frost Heave and Thaw Weakening Susceptibility of Soils《土壤对冻胀和解冻变弱敏感性的标准试验方法》.pdf

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1、Designation: D 5918 06Standard Test Methods forFrost Heave and Thaw Weakening Susceptibility of Soils1This standard is issued under the fixed designation D 5918; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revi

2、sion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 These laboratory test methods cover the frost heave andthaw weakening susceptibilities of soil that is tested in thelaborator

3、y by comparing the heave rate and thawed bearingratio2with values in an established classification system. Thistest was developed to classify the frost susceptibility of soilsused in pavements. It should be used for soils where frost-susceptibility considerations, based on particle size such as thel

4、imit of 3 % finer than 20 mm in Specification D 2940, areuncertain. This is most important for frost-susceptibility crite-ria such as those used by the Corps of Engineers,3that requirea freezing test for aggregates of inconclusive frost classifica-tion. The frost heave susceptibility is determined f

5、rom theheave rate during freezing. The thaw weakening susceptibilityis determined with the bearing ratio test (see Test MethodD 1883).1.2 This is an index test for estimating the relative degree offrost-susceptibility of soils used in pavement systems. It cannotbe used to predict the amount of frost

6、 heave nor the strengthafter thawing, nor can it be used for applications involvinglong-term freezing of permafrost or for foundations of refrig-erated structures.1.3 The test methods described are for one specimen anduses manual temperature control. It is suggested that fourspecimens be tested simu

7、ltaneously and that the temperaturecontrol and data taking be automated using a computer.1.4 All recorded and calculated values shall conform to theguide for significant digits and rounding established in PracticeD 6026.1.4.1 The procedures used to specify how data are collected/recorded and calcula

8、ted in this standard are regarded as theindustry standard. In addition, they are representative of thesignificant digits that should generally be retained. The proce-dures used do not consider material variation, purpose forobtaining the data, special purpose studies, or any consider-ations for the

9、users objectives; and it is common practice toincrease or reduce significant digits of reported data to becommensurate with these considerations. It is beyond the scopeof this standard to consider significant digits used in analysismethods for engineering design.1.4.2 Measurements made to more signi

10、ficant digits orbetter sensitivity than specified in this standard shall not beregarded a nonconformance with this standard.1.5 This Standard is written using SI units. Inch-pound unitsare provided for convenience. The values stated in inch poundunits may not be exact equivalents; therefore, they sh

11、all beused independently of the SI system. Combining values fromthe two systems may result in nonconformance with thisstandard.1.5.1 The gravitational system of inch-pound units is usedwhen dealing with inch-pound units. In this system, the pound(lbf) represents a unit of force (weight), while the u

12、nit for massis slugs. The rationalized slug unit is not given, unless dynamic(F=ma) calculations are involved.1.5.2 It is common practice in the engineering/ constructionprofession to concurrently use pounds to represent both a unitof mass (lbm) and of force (lbf). This implicitly combines twosepara

13、te systems of units; that is, the absolute system and thegravitational system. It is scientifically undesirable to combinethe use of two separate sets of inch-pound units within a singlestandard. As stated, this standard includes the gravitationalsystem of inch-pound units and does not use/present t

14、he slugunit for mass. However, the use of balances or scales recordingpounds of mass (lbm) or recording density in lbm/ft3 shall notbe regarded as nonconformance with this standard.1.6 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresp

15、onsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:41These test methods are under the jurisdiction ofASTM Committee D18 on Soiland Rock and are

16、 the direct responsibility of Subcommittee D18.19 on Frozen Soilsand Rock.Current edition approved Nov. 1, 2006. Published December 2006. Originallyapproved in 1996. Last previous edition approved in 2001 as D 591896(2001).2Sometimes called California Bearing Ratio (CBR).3The Army Corps of Engineers

17、 uses a frost susceptibility classification proce-dure (TM 5-818-2) based on particle size criteria and the Unified Soil ClassificationSystem (MIL-STD-619) field. Furthermore, this test should only be used forseasonal freezing and thawing conditions and not for long-term freezing ofpermafrost or of

18、foundations of refrigerated structures.4For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1*A Summary of Changes

19、 section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.C 670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction MaterialsD75 Practice for Sampling AggregatesD 42

20、0 Guide to Site Characterization for Engineering De-sign and Construction PurposesD 653 Terminology Relating to Soil, Rock, and ContainedFluidsD 698 Test Methods for Laboratory Compaction Character-istics of Soil Using Standard Effort (12,400 ft-lbf/ft3(600kN-m/m3)D 1587 Practice for Thin-Walled Tub

21、e Sampling of Soilsfor Geotechnical PurposesD 1883 Test Method for CBR (California Bearing Ratio) ofLaboratory-Compacted SoilsD 2216 Test Methods for Laboratory Determination of Wa-ter (Moisture) Content of Soil and Rock by MassD 2940 Specification for Graded Aggregate Material ForBases or Subbases

22、for Highways or AirportsD 3550 Practice for Thick Wall, Ring-Lined, Split Barrel,Drive Sampling of SoilsD 3740 Practice for Minimum Requirements for AgenciesEngaged in the Testing and/or Inspection of Soil and Rockas Used in Engineering Design and ConstructionD 4083 Practice for Description of Froze

23、n Soils (Visual-Manual Procedure)D 6026 Practice for Using Significant Digits in Geotechni-cal DataE 105 Practice for Probability Sampling Of MaterialsE 122 Practice for Calculating Sample Size to Estimate,With a Specified Tolerable Error, the Average for aCharacteristic of a Lot or Process2.2 Milit

24、ary Standards:Army TM 5-818-2 Pavement Design for Frost Conditions,January 19855MIL-STD-619 Unified Soil Classification System forRoads, Airfields, Embankments and Foundations53. Terminology3.1 Definitions:3.1.1 Definitions of the soil components of a freezing andthawing soil system shall be in acco

25、rdance with the terminol-ogy in Terminology D 653.3.1.2 Definitions of the components of freezing and thawingsoils shall be in accordance with the terminology in PracticeD 4083.3.2 Definitions of Terms Specific to This Standard:3.2.1 The following terms are used in conjunction with thedetermination

26、of the frost-susceptibility of soils and supple-ment those in Practice D 4083 and in the glossary on perma-frost terms by Harris et al.63.2.1.1 degree of frost-susceptibility the relative propen-sity for frost heave or thaw weakening in comparison to that foranother soil or to an acceptable level of

27、 change.3.2.1.2 freeze-thaw cyclingthe repeated freezing andthawing of soil.3.2.1.3 freezing (soil)the changing of phase from water toice in soil.3.2.1.4 freezing, closed systemfreezing that occurs underconditions that preclude the gain or loss of any water in thesystem.3.2.1.5 freezing, open system

28、freezing that occurs underconditions that allow gain or loss of water in the system bymovement of pore water from or to an external source togrowing ice lenses.3.2.1.6 freezing-point depressionthe number of degreesby which the freezing point of an earth material is depressedbelow the freezing point

29、of pure water.3.2.1.7 frost heavethe upward or outward movement ofthe ground or pavement surface (in the direction of heat flow)caused by the formation of ice in the soil.3.2.1.8 frost heave ratethe rate at which the ground orpavement surface moves upward or outward.3.2.1.9 frost heave susceptibilit

30、ythe propensity for a soilto accumulate ice during freezing and to heave.3.2.1.10 frost-susceptible soilsoil in which ice accumula-tion causes frost heave during freezing or thaw weakeningduring thawing, or both.3.2.1.11 ice lensa lens-shaped body of ice of any dimen-sion that forms during unidirect

31、ional freezing of soil, the longdimension being in the direction normal to the direction of heatflow.3.2.1.12 ice nucleationthe formation of an ice nucleusfrom water.3.2.1.13 refrigerated structuresartificially refrigeratedstructures (cold storage facilities, liquefied gas tanks, iceskating rinks, c

32、hilled gas pipelines, and so forth) that cause thefreezing of their foundations.3.2.1.14 relative frost susceptibilitythe amount of frostheave or thaw weakening of a soil in relation to other soils.3.2.1.15 seasonally frozen groundground that freezes andthaws annually.3.2.1.16 thaw weakeningthe redu

33、ction in strength, bear-ing capacity, or stiffness modulus below the normal warm-season values. This is caused by the decrease in effective stressresulting from the generation and slow dissipation of excesspore water pressures when frozen soils containing ice arethawing.3.2.1.17 thaw weakening susce

34、ptibilitythe propensity forthe strength or stiffness modulus of a soil to decrease below thenormal warm season values.3.2.1.18 unidirectional freezingsoil freezing that occursin one direction only.4. Summary of Test Methods4.1 Two freeze-thaw cycles are imposed on compacted soilspecimens, 146 mm (5.

35、75 in.) in diameter and 150 mm (6 in.)in height. The soil specimen is frozen and thawed by applyingspecified constant temperatures in steps at the top and bottomof the specimen, with or without water freely available at the5Available from Superintendent of Documents, U.S. Government PrintingOffice,

36、Washington, DC 20402.6Harris, S. A. et al, Glossary of Permafrost and Related Ground-Ice Terms,Permafrost Subcommittee, Associate Committee on Geotechnical Research, Na-tional Research Council of Canada, Technical Memorandum No. 142, Availablefrom National Research Council of Canada, Ottawa, Ontario

37、, Canada, K1A0R6,1988.D5918062base; a surcharge of 3.5 kPa (0.5 lbf/in.) is applied to the top.The temperatures imposed on the specimen are adjusted to takeinto account the freezing point depression attributable to saltsin the soil. At the end of the second thawing cycle, the bearingratio is determi

38、ned. The entire testing procedure can becompleted within a five-day period.This testing procedure maybe conducted manually or it may be controlled by a computer.NOTE 1The quality of the results produced by this standard isdependent on the competence of the personnel performing it, and thesuitability

39、 of the equipment and facilities. Agencies that meet the criteriaof Practice D 3740 are generally considered capable of competent andobjective testing/sampling/inspection/etc. Users of this standard are cau-tioned that compliance with Practice D 3740 does not in itself assurereliable results. Reliab

40、le results depend on many factors; Practice D 3740provides a means of evaluating some of those factors.5. Significance and Use5.1 These test methods can be used to determine the relativefrost-susceptibility of soils used in pavement systems. Both thefrost heave susceptibility and the thaw weakening

41、susceptibil-ity can be determined.5.2 These test methods should be used only for seasonalfrost conditions and not for permanent or long-term freezing ofsoil. These test methods also have not been validated foranything other than pavement systems.5.3 These test methods cannot be used to predict the a

42、mountof frost heave or thaw weakening in the field. Its purpose is todetermine the relative frost-susceptibility classification for usein empirical pavement design methods for seasonal frostregions.6. Apparatus6.1 Compaction MoldThe mold assembly (see Fig. 1)shall consist of a steel base plate, a st

43、eel hollow cylinder splitinto three sections longitudinally, two acrylic spacer disks, sixacrylic rings, a steel collar, a rubber membrane, and four hoseclamps.6.1.1 Base PlateA 203-mm (8-in.) square steel base plate(see Fig. 1) with a thickness of 25 mm (1.0 in.) and a 6.0-mm(0.25-in.) recess to re

44、ceive and retain the steel side walls andbase of the specimen. Two 9.5-mm (0.375-in.) diameterthreaded holes at opposite corners accommodate clampingrods.6.1.2 Compaction CylinderA hollow steel cylinder withan inside diameter of 152.4 mm (6 in.), a wall thickness of 9.5mm (0.375 in.), and a length o

45、f 165.1 mm (6.5 in.). Thecylinder is to be made in three sections that part along thevertical axis (see Fig. 1).Arecess in the steel base plate acceptsthe steel cylinder and restrains it from expanding duringcompaction.6.1.3 CollarAsteel collar with a 146-mm (5.75-in.) insidediameter and a 185-mm (7

46、.25-in.) outside diameter with a152.4-mm (6-in.) diameter recess bored 6.35 mm (0.25 in.) intothe bottom. This collar slips over the top of the steel mold toconstrain expansion and to provide extra space for soil duringcompaction. Flanges slide over the steel rods to hold the collarin place.6.1.4 Sp

47、acer DiskTwo circular acrylic spacer disks (seeFig. 1), 158.8 mm (6.25 in.) in diameter and 6.4 mm (0.25 in.)in height. One spacer disk is placed at the bottom of thecompaction mold. The second disk is placed on the top of thespecimen during transport and storage.6.1.5 RingsSix acrylic rings (see Fi

48、g. 1 and Fig. 2) havingan inside diameter of 146 mm (5.75 in.) and a height of 25 mm(1 in.) with a wall thickness of 3.18 mm (0.125 in.).A3.18-mmdiameter hole shall be drilled at the midheight in each ring toreceive a temperature sensor. The top and bottom rings shallhave a 3.18-mm square notch cut

49、in one edge to receive the topand bottom temperature sensor leads. Each ring shall have asplit cut through its height at a location diametrically oppositethe temperature sensor hole.6.1.6 Clamping RodsTwo 9.5-mm (0.375-in.) diameter by215.9-mm (8.5-in.) long threaded steel rods with two wing nutsto clamp the assembly together.6.1.7 Rubber MembraneA0.36-mm (0.014-in.) thick rub-ber membrane without holes or defects. This is required to sealthe sides of a soil specimen that shall be 146.0 mm (5.25 in.)in diameter. The length of the membrane shall be at least