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J~1 D 4643
<br />I1.7 should be performed.
<br />Note 8-InmementN heating, together with st'uring, will minimize
<br />overheating and localized drying of the soil, thereby yielding results mare
<br />caasistrnt with results abmined by Test Method D 2216. The recom-
<br />mended tmre inaemmu hove been suitable for most specimens having
<br />particles smeller rhea a No. 4 sieve and with a mass of approximately 200
<br />g; however, they may not be appropriate for all soils and ovens, and
<br />adjustttrmt may be oecessery.
<br />Nrrrc 9-Water cmtmt specimens shoWd be discarded after testing and
<br />oat uud in any °ther tests due to Parocle breakdown, chemical changes or
<br />losses, melting, or loses of organic eaattimmtl.
<br />mass after the final incremental drying periods.
<br />13.1.8 Identification of comparison test(s) if performed, and
<br />the method of test utilized.
<br />13.1.9 Identification of the microwave oven and the drying
<br />settings and cycles used, when standazdized drying is utilized.
<br />Note 10-Water (moistare) c®tmt deoetmimtioav conducted in eccor-
<br />dance with Test Method D 2216 or other methods may be recorded oa the
<br />same reparL This is not a mandatary requiremm4 but may be cOrrvenimt
<br />when the resWts of the two methods ere m be cranpared
<br />14. Pretisio¢ and Bias
<br />12. Calctilations
<br />12.1 Calculate the water wntent of the soil as follows:
<br />w =[(mass oC water)/(mass of ovmdried soil)] x 1110 (1)
<br />w = [(M, - M~!(MZ - Mr)] x 100 = M,/M, x 100
<br />where:
<br />w =water content, %,
<br />Mt =mass of container and moist specimen, g,
<br />Mz =mass of container and avendried specimen, g,
<br />M° =mass of container, g,
<br />M,,, =mass of water, g, and
<br />M, =mass of solid particles, g,
<br />13. Report
<br />13.1 The report (data sheet) shall include the foLlawing.
<br />13.1.1 Identification of the sample (material) being tested,
<br />by boring number, sample ntnnbet, test number, and the like.
<br />13.1.2 Water content of the specimen to the nearest 0.1 or
<br />1 %, depending on the purpose of the test.
<br />13.1.3 Indicate if test specimen has a mass less than the
<br />minimum indicated in Table 1.
<br />13.1.4 Indicate if test specimen contains more than one soil
<br />type (layered, and the like).
<br />13.1.5 Indication of any material (size, amormt, and layer or
<br />layer sequences) excluded from Ote test specimen.
<br />13.1.6 Timc and setting of initial drying period and subse-
<br />quent incremental drying periods.
<br />13.1.7 Initial mass of test specimen prior w drying, and the
<br />14.1 Precision-Studies on microwave drying have indi-
<br />cated asingle-laboratory average precision of 0.96 °~6 or less,
<br />depending upon the soil type, initial moisture, and specimen
<br />size.
<br />14.2 The precision of this test method is opemtor-
<br />dependent, and is a function of the care exercised in perform-
<br />ing the steps of ilte procedttre, giving particulaz attention to
<br />careful control and systematic repetition of the procedures
<br />used.
<br />14.3 Bias-There is ¢o accepted reference value for this test
<br />method, therefore, bias cannot be determined.
<br />14.3.1 Studies to determine bias between this test method
<br />atld Test Method D 2216 using a convection drying oven
<br />indicate that the mean difl'enence between the value of water
<br />content, expressed as a percentage of mass, when tested by the
<br />microwave oven and the convection oven is 0.24 % for
<br />micaceous soils (having 5 to 25 %mica paRiclcs by mass), end
<br />0.61 % for other soils. The standazd deviation of the value of
<br />the difference between the water content, expressed as a
<br />percentage of mass, by the microwave and convection oven
<br />methods is 01 °fo for the micaceous soils and 0.3 % fair o01er
<br />soils.
<br />14.4 Subcommittee D18.08 is seeking pertinent data from
<br />users of this test method on precision and bias compazisons.
<br />15. Keywords
<br />15.L microwave; microwave moisuue; microwave oven;
<br />moisture content; rapid moisture test; water content
<br />REFERENCES
<br />(1) Hageny, D. J., Ullrich, C. R, and Dmro0. M M, "Microwave Drying
<br />of Soik;' Georahnieal Testing Journol, Yol ] 3, No. 2, Ittoe 1990, pp.
<br />136-141.
<br />(2) Hagerty, D. 7., Ullrich, C. R., and Callan, C. A.;' Microwave Drying
<br />of Highly Plastic and Organic Soils," Gealechrricol Tatting Journal,
<br />Vol 13, N°. 2, lone 1990, pp. 142-145.
<br />(3) Charlie, W. A., Yon Guatm, M W., and Doehring, D. O.,'Tempera-
<br />nrre Controlled Microwave Drying of Soils," Gearechniwl TuNng
<br />lournd, Vol 5, No. 3/4, SeptJDec. 1982.
<br />(4)Gilbert, P. A., "Computer Controlled Micmweve Oven System far
<br />Rapid Water Con[mt Determinetiaq" 7eclurical Report GL-SB-21,
<br />Department of the Amy, Waterways Experiment Station, Corps of
<br />Engineers, Ycksbtug, MS, November ]988.
<br />(5) U.S. Departmm[ of the Interior, "ITocedme for Determining Moisture
<br />Content of Soils by the Microwave Method" Earth Manual, Part 2,
<br />USHR S31S89, Bureau of Reclamation, Denver CO, 1986.
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