AASHTO T 100-75-82 - ASTM D 854-58-72 - Grav - Espe.

 

326

METHOOS OF SAMPLING ANO TESTING

Standard M ethod ethod of Test or Specific Gravity of Soils AASHTO DESIGNATION DESIGNATION:: (ASTM DESIGNATION: DESIGNATION:

T 100-75 1982)1 D854-58 (1972»

1. SCOPE 1.1 This method of test is intended for determining the specific gravity of soils by means meansof of a pycnometer. When the soil is composed composedof of particles llarger arger than the 4.75 mm (N (No. o. 4) sieve. he method outlined in the Standard Method of Test for Specific Gravity and Absorption of Coarse A.ggregate (AASHTO T 85) shal shalll be ollowed. When the soil is composed composedof of particles both larger and smaller than the 4.75 mm sieve. the sampleshall be separated on the 4.75 mm sieveand sieveand the appropriate methodof test usedon usedon eachportion. eachportion. The specific gravity value for the soil shall be the weighted average averageof of the two values. When the specific gravity value is to be used n calculations in connection with the hydrometer portion of the Standard Method of Mechanical Analysis of Soils(AASHTO T 88) it is intended that the specific gravity test be made on that portion of the soil which passes he 2.00 mm (No. 10)or 0.425 mm (No. 40) sieve. as appropri appropriate. ate. 2. DEFINITION 2.1 SpeC tic Gravity'-Specific gravity is the ratio of the mass in air of a given volume of a material at a stated temperature to the mass n air of an equal volume of distilled water at a stated temperature.

3. APPARATUS 3.1 The apparatus shall consist of the 1()llowing: íl.I Pycnometer-Either a volumetric flask having a capacity of at least 100mI or a stoppered bottle having a capacity of at least 50 mI (Note 1). The stopper shall be of the salDematerial as the bottle, and of such size and shape that it can be easil easily y inserted to a fixed depth in the neck of the bottle, and shall have a small hole through its center to permit the emissioff of air and surplus water. NOTE1NOTE 1- The use of either the volurnetric nask or the stop~ stop~ bottle is a rnatter rnatter of individual preference. but in general. the nask should be used when a largor sarnple thancan be used in the stopperedbottle stopperedbottle is needed duo to rnaxirnurn grain sizo of the sarnple.

3.1.2 Balance--Either a balance sensitive to 0.01 g for use with the volumetric flask. or a balancesensitive o 0.001 g for use with the stoppered stopperedbottle. bottle. 3.1.3 Desiccator-A desiccator. about 8 in., (approx. 200 mm) in diameter containing anhydrous silica gel or other suitable desiccant. 3.1.4 Oven-A thermostatically controlled drying oyencapable of maintaini maintaining ng a temperature of 110.:f:.5 C (230.:f:. (230.:f:.9 9 F). 3.1.5 Thermometer-A thermometer covering the range of O-SOC (32-122 F), readable and accurate to l C (2 F).

.-

'Ex~pt for the requirementsiyen or desiccator, yen hermometer nd weighing weighings s the same sameas as ASTM D

854-58 1972).

'This delinition conforms o the standard standardDelinition Delinition of Terms Relating o Specilic SpecilicGrayity Grayity (AASHTO M 132).

 

TlOO

METHODS OF SAMPLING AND TESTING

327

4. GENERAL REQUIREMENTS FOR WEIGHING 4.1 When the volumetric tlask is used n the spe specific cific gravity determination all massesshall massesshall be determined to the nearest0.01 nearest0.01g. When the stoppered bottle bottle is used n the specific gravity determination all massesshall massesshall be determined to the nearest0.001 nearest0.001 g. S. CALIBRATION OF PYCNOMETER 5.1 The pycnometer pycnometer shall becleaned.dried. weigheC:, nd the mass ecorded. The pycnometer shall be tilled with distilled water (Note2) essentially essentiallyat at room temperature. temperature. The mass of the pycnometer and water. W". shall be determined and recorded. A thermometer shall be nserted in the water and its temperature Ti determined to the nearest whole degreeo NOTE 2-Kerosine is a better wetting agenllhan water for mosl soils and may be used in place of dislilled water for oven-dried sampleso

5.2 From the massW. determined at the observed observed emperature Ti a table of values values of massesW. shall beprepared beprepared for a seriesof temperatures that are likely to prevail when massesWb Wbare are determined later (Note 3). These values of W. shall becalculated becalculated as follows: W. (at T.) =

density of water at T. T.

o ~ (W.(at Ti) -Wj) denslty of water at Ti

+ Wj

W. = mass of pcynometer and water. in grams. W¡ = mass of pycnometer, in grams. T, = observed temperature of water, in degreesCelsius,and T. = any other desired temperature, temperature, in degreesCelsius. degreesCelsius. NOTE 3: This melhod provides a procedure hal is mosl convenien for laboratorios rnaking rnany delerminalions wilh Ihe sapycnomelero 1I is equally applicable applicable o a single delermination. Bringing the pycnometerand conlents lo some designaled emperalure when ma W. and W, are aken. aken. requires considerable ime. 1I s much more convenienllo prepare a lable of massesW. for various lemperalures likely to prevail when massesW, massesW, are lakeno lakeno 1I is importanl that massesW. massesW. and W, be based on water allhe satemperature. Values or Ihe relativo densilY of water allemperatures from 18 to 30 C are given in Table l.

6. SAMPLE 6.1 The soil to be used n the specific gravity test mar contain its natural moisture or be ovendriedoThe driedo The massof massof the test sample sample on an oven-drybasis shall be at least 25 g when tthe he volumetric tlask is lo be uscd. and at least 10 g when the stoppered bottle is to be used. 6.2 SamplesContaining SamplesContaining Natural Moisture--When the sample contains its natural moisture, he massofthe mass ofthe soil. Wo. on an oven-dry basis shall be determined determined at the end ofthe test by evaporating the water in an oyen maintained at 110.:1:.5C (230 :1:. F) (Note 4). Samplesof cIar soils containing their natural moisture content shall be dispersed in distilled water befo before re placing in the tlask. using the dispersing equipment specified in AASHTO T 88. 6.3 Oven-Dried Samples-When Samples-When an o oven-dried ven-dried sample s to be used, the sample shall be dried t'or at least 12h, or,to constant constant mass at 110.:1:.5C (230.:1:.9F) (Note4). (Note4). transferred transferred to pycnometerand pycnometerand weighed. The sample shall then be soaked soaked n distilled water for at least 12 h. NOTE4-Drying of certain soils al 110 C may bring aboulloss of moislure 01' composilion or hydraliono and in such casesdrying NOTE4-Drying casesdrying shall be done. if desiredo n reduced air pressureand pressureand al a lower emperalureo

7. PROCEDURE 7.1 The samplecontaining natural natural moisture shallbe placed n the pycnometer, pycnometer,Cl11C Cl11Ceing eing taken not to lose any of the soil in case he mass of the sample sample has been beendetermined. determined. Distilled water shall be added to fill the volumetric tlas~ about three.fourths full or the stoppered stopperedbottle bottle about half full. 7.2 Entrapped air shall be be removed by either of the following methods: ((J) J) by subjecting the CI)ntcnts o a partial vacuum (air pressure pressure not exceeding 100 mm of mercury) or (2) by boiling gently

 

328

METHOOS OF SAMPLING ANO TESTING

lo.. at least 10 mino while occasionally rolling the pycnometer to assist in the removal of the air. Subjcction of the contents to reduced air pfessure may be done either by connecting the pycnometer dircctly to an aspirator or vacuumpump. or by useof useof a bell jaro Some soils boj] vio]ently when subjected to rcduced air pressure. It will be necessary necessaryn n thosecases o reduce he air pressure at a slower ate or to use ¡ larger tlask. Samp]es hat hat are heatedshall be cooled o room temperature. 7.3 The pycnometershall then be filled filled with distilled water and the outside cleaned and dried with a clcan. dry cloth. The mass massof of the pycnometerand contents. W h. and the temperature in degrees Cel ;ius. Tx' of the contents shall be determined, determined, as described in Section4. Section4. (Note S) Note 5- The mínimum volum volume e of slurry that canbe p prepared repared by dis dispersing persing equipment specitied n AASHTO T 88 is such that a SOO mi. Ilask i, needed as the pyncometer

8. CALCULATION ANO REPORT 8.1 follows:

The specific gravity of the soil. based on water at a temperature temperature ~\"shall be calculated as w Specific ravity.T,IT.c ravity.T,IT.c = Wo + lit; a-W ~

w¡'.r..:

W = mass of sample ofoven-dry soil. in gr gramo. amo. w" = mass of pycnom pycnometer eter illed with water at temperature Tx (Note ó). in gramo. ~ = mas, of pycnometer illed with water and soil at temperature T .in gramo. and Tx = temperature of the cont contento ento of the pycnometer when w weight eight W b zwas etermined. in degrees degreesCelsius Celsius

Note -This valgo shall be taken from the labIo ofvalues of Wa prepared in accordancewith accordancewith 5.1 for the temperature temperature prevailing when mas, W b was aken.

8.2 Unless otherwiserequired. specific gravity gravity valuesreported shall be based basedon water at 20 C. Thc value based on water at 20 C shall be calculated from the value based on water at the observed temperature ~\:' as follows: Speciticgravity. Tx12.0 x12.0C C = K X specitic gravity. T T xC, wher,,: K = a number found by dividing the relativ relativo o density of water at temperature Tx by the relativo density ofwater at 20 C. Values for for a r'ln~e of te temperatures mperatures are given n Table l.

8.3 When it is desired to report the specific gravity value based on water at 4 C. such a specific specific ~":lvlty value may be ca]culated by multiplying the specific gravity value at temperature Tx by the rcl¡¡tive dcnsity of water ;¡t temperature T x. 8.4 When any portion of the original sample of soil is eliminated in the preparation of the test sample. thc portion on which the test has been made shall be reported. TABLE 1 Relative Density of Water and Conversion Factor K for Various Temperatures

If,\ ,

""'i

IlJ,r;? ,rll .1

,¡.r,

18 19 20 21 22

,

;

Temperature.

del. Ceot. ;

23

24 25

26 27... 28...

-

ro::::::::::::::::::::: ro:::::::::: :::::::::::::::::::::: :::::::::::::: :::

;;;.'""

Re ative Density

of Water :,...0.9986244 0.9984347 0.9982343 0.9980233 0.9978019

1.0004 1.0002 1.0000 0.9998 0.9996

0.9973286 0.9970770

0.9991 0.9989

0.9975702

0.9993

0.9968156 0.9965451 g:;;~~~~¡

0.9986 0.9983 g:;;~~

0.9956780

0.9974