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~) D 4643
<br />noncorrodible airtight containers at a temperature between
<br />approximately 3 and 30°C in an area that prevents direct
<br />exposure to sunlight
<br />8.2 The water content determination should be performed as
<br />soon as practical after sampling, especially if potentially
<br />coaodible containers (such as steel thin-walled tubes, paint
<br />cans, and the Itke) or unsealed sample bags are used.
<br />9. Test Specimen
<br />9.1 For water contents being determined as part of another
<br />ASTM test method, the specimen selection process and tech-
<br />niques specified in that test method should be followed.
<br />9.2 The manner in which the test specimen is selecud and
<br />its required mass is basically dependent on the purpose
<br />(application) of the test, type of material being tested, and the
<br />type of sample (specimen from another test, bag, tube, split-
<br />barrel, and the like). ]n all cases, however, a representative
<br />portion of the total sample shall be selected. If a thinly layered
<br />soil or more than one soil type is enwtmteted, select m
<br />average portion or individual portions, or bolt, and note which
<br />portion(s) was tested in the report of the resulu.
<br />9.2.1 For bulk samples, select the test specimen from the
<br />material after it has been mixed thoroughly. The mass ofmoist
<br />material selected shall be in accordance with Table I.
<br />9.2.2 For small (jar) samples, select a representative portion
<br />in accordance with the CoIlowing prmcadrae:
<br />9.2.2.1 For cohesionless soils, mix thorottgWy the material,
<br />then select a test specunen having a mass of moist material in
<br />accordance with Table 1.
<br />9.2.2,2 For cohesive soils, remove about 3 tram of material
<br />from the exposed periphery of the sample and slice the
<br />remaining specimen is half (to check if the material is layered),
<br />prior to selecting the test specimen. If the soil is layered, see
<br />9.2. The mass of moist material selected should be in accor-
<br />dance with Table 1, if coarse-grained particles are noted.
<br />Breaking trc cutting of cohesive samples to approximately
<br />6-mm (t/a-in.) particles will speed drying and prevea[ crusting
<br />or the overheating of the surface while drying the interior.
<br />9.3 Using a test specimen smaller than the minimum mass
<br />indicated previously requires discretion, though it may be
<br />adequate for the propose of the test. A specimen having a mass
<br />less than the previously indicated value shall be noted in the
<br />report of the results.
<br />Noce 5-ia many caves, whm working wi[h a sma0 sample containing
<br />a relatively large coarse-gained particle, ii is appropriate not to include
<br />dos pvdcle in the [est spaimm. It this oaun, it should be noted m dte
<br />report of the resdb.
<br />9.4 lNhea results of a water (moisttre) contem detemvna-
<br />tion by the use of this test method are to be compared to the
<br />results of another method, such as Test Method D 2216, a
<br />second sample should be oblaiaed daring the selection of the
<br />TA6LE t Tast Spaelttsan Nasaea
<br />Sieve RBlaiavq Not MatB Then ftawmmended Mesa of
<br />AboN 7016 d Semple Malst Spximen, g
<br />20 mm (NO. 10) 100 m 200
<br />4.75 mm (NO. 4) 300 W 500
<br />19 mm (i'. in.) 500 b 1000
<br />sample for this test method. Precautions should be taken to
<br />obtain a sample of the same water (moisture) content. The
<br />comparison sample should be processed as quickly as possible
<br />to avoid moisttae losses.
<br />10. Conditioning
<br />10.1 Prryate and process the specimens es quickly as
<br />possible to m;n;mi~e unrecorded moisture loss that will result
<br />in erroneous water content determinations.
<br />10.2 Cut or break up the soil into small size aggregations w
<br />aid in obtaining more uniform drying of the specimrn
<br />10.3 1f the specimens are not to be tested immediately, store
<br />them in sealed containers to prevent loss of moisture.
<br />11. Procedure
<br />ll.l Determine the mass of a ciean, dry container or dish,
<br />and record.
<br />11.2 Place the soil specimen in the container, and immedi-
<br />ately determine mtd record the mass.
<br />11.3 Place the soil and container im a microwave oven with
<br />the heat sink and ttan the ovm on far 3 min If experience with
<br />e particular soil type and specimen size indicates shorter or
<br />longer initial drying times can be used without overheating, the
<br />initial and subsequent drying times may be adjusted.
<br />Non 6--The 3-mm inidal xrdng is for a minimum s®ple mass of
<br />100 g, as indicated in Table 1. Smaller samples are not remmmmdcd
<br />whm using the microwave ovm because drying may b< too rapid for
<br />pmprr control. When very large samples are needed to represent soil
<br />containing Wge gravel particles, the sample may veed to he split imo
<br />segments and dried sepaately m obtain t~ dry mass of the total temple.
<br />Non 7-Most wens have a variable power xtting. For the majority of
<br />soils tested, a setting of "high" should be satisfacmry; however, far some
<br />soils such a xtung tnay be too severe. The proper setting csa be
<br />detemriaed ody tlnotrgh tlr ux of end experience with a pardmlar ovm
<br />for various soil types and sample sizes. The energy output of microwave
<br />ovens may decease witb age and usage; thaefoze, power se[dngs and
<br />drying time should be embGshed !or earl oven
<br />11.4 After the se[ time has elapsed, remove fire container
<br />and soil liven the ov®, either weigh the specimen immediately,
<br />ar place in desiccator to cool to allow handling and to prey®t
<br />damage to the balance. Determine and record tlu mass.
<br />11.5 With a small spatula ar knife or short length of glass
<br />rod carefully m;x the soil, taking special precaution not to lose
<br />any soil.
<br />11.b Remm the container and soil to the oven and reheat in
<br />the oven for 1 min.
<br />11.7 Repeat 11.4-ll.ti, tntil the change between two con-
<br />secutive mass detemminations would have an insignificant
<br />effect an Ore calculated moisttae tout®t A change of 0. I °/a ar
<br />less of the initial wet mass of the soil should be acceptable for
<br />most specimens.
<br />11.8 Use the final mass detemtjnadon in calculating the
<br />water content Obtain this value immediately otter the heating
<br />cycle, or, if the mass determination is to be delayed, after
<br />cooling in desiicata.
<br />l l.9 When routine testing of similar soils is cwtemplated,
<br />the drying times and ntmmber of cycles may be standardized for
<br />each oven, When standardized drying times and cycles are
<br />utilized, periodic verification m assure that the results of the
<br />final dry mass determination are equivalent to the procedure in
<br />
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