AASHTO T 265 - LABORATORY DETERMINATION OF MOISTURE CONTENT OF SOILS
Conduct this procedure according to AASHTO T 265. Consult the current edition of AASHTO for procedure in its entirety and equipment specification details.
SCOPE This procedure is used to determine the total moisture content of a soil. The soil is dried to remove all free moisture. This test measures the weight of the moisture removed from the soil.
APPARATUS Oven Balance Sample containers with cover
PROCEDURE Record all weights to the nearest 0.1 g or 0.1%. Weigh a clean, dry, and empty container including the cover and record as tare weight. Determine sample size needed from the table below. The sample obtained must be representative of the soil. Maximum Particle Size No. 40 (0.425 mm) sieve No. 4 (4.75-mm) sieve 1/2" (12.5 mm) 1" (25.0 mm) 2" (50 mm) Minimum Mass of Sample 10 g 100 g 300 g 500 g 1000 g
Place sample in container and cover to prevent moisture loss. Weigh sample and record as mass of original sample. To dry sample, remove cover and place in oven at temperature of 2309F (1105C). A sample allowed to dry overnight, or 15 to 16 hours, is considered dried
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to a constant weight. Remove sample from the oven, cover, and allow too cool before placing on balance. Weigh the sample with cover and record this weight as dry weight. If the sample is not allowed to dry overnight, place the sample in the oven for a period of time. Remove sample from the oven, cover, and allow too cool before placing on balance. Weigh the sample and record the reading. Repeat the process until two successive readings show a constant weight. Record the final weight as mass of dry sample. Discard sample after test.
CALCULATIONS Calculate the percent moisture as follows: A = ((B C)/C) x 100 A = Percent moisture B = Mass of original sample C = Mass of dry sample REPORT Report moisture to the nearest 0.1%.
NOTES Constant weight is defined as when further drying will cause less than 0.1% additional loss in mass when weighed at specified intervals. Specified weighing interval for oven drying of samples is one hour.
CALIBRATION Calibration is to be done annually, as a minimum, and whenever damage or repair is needed.
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AASHTO T 265 (Modified)
Laboratory Determination of Moisture Content of Soils AASHTO T 265 has been adopted by WSDOT with the following definition for Constant Mass.
Constant Mass Test samples dried at a temperature of F (C) to such a condition that it will not lose more than 0.1 per cent moisture after 2 hours of drying. Such a condition of dryness can be verified by determining the mass of the sample before and after successive 2 hour drying periods. In lieu of such determination, samples may be considered to have reached constant mass when they have been dried at a temperature of F (C) for an equal or longer period than that previously found adequate for producing the desired constant mass condition under equal or heavier loading condition of the oven.
WSDOT Materials Manual January 2009

M 46-01.03

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Laboratory Determination of Moisture Content of Soils

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WSDOT Materials Manual M 46-01.03 January 2009
Performance Exam Checklist
Laboratory Determination of Moisture Content of Soils FOP for AASHTO T 265

Participant Name

Exam Date Yes No
Procedure Element 1. The tester has a copy of the current procedure on hand? 2. All equipment is functioning according to the test procedure, and if required, has the current calibration/verification tags present? 3. Representative sample of appropriate mass obtained? 4. Mass of clean, dry container determined? 5. Sample placed in container and mass determined? 6. Test sample mass conforms to the required mass? 7. Sample mass determined to 0.1 percent? 8. Loss of moisture avoided prior to mass determination? 9. Sample dried in a drying oven at 0F (0C)? 10. Sample dried to a constant mass? 11. Sample cooled prior to mass determination? 12. Calculations performed properly and results reported to the nearest 0.1 percent or better of the original sample? First attempt: Pass Signature of Examiner Comments: Fail Second attempt: Pass Fail

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