1、Standard Method of Test for Laboratory Determination of Moisture Content of Soils AASHTO Designation: T 265-15 American Association of State Highway and Transportation Officials 444 North Capitol Street N.W., Suite 249 Washington, D.C. 20001 TS-1a T 265-1 AASHTO Standard Method of Test for Laborator
2、y Determination of Moisture Content of Soils AASHTO Designation: T 265-15 1. SCOPE 1.1. This method covers the laboratory determination of the moisture content of soils. 1.2. The following applies to all specified limits in this standard: For the purposes of determining conformance with these specif
3、ications, an observed value or a calculated value shall be rounded off “to the nearest unit” in the last right-hand place of figures used in expressing the limiting value, in accordance with ASTM E29. 2. REFERENCED DOCUMENTS 2.1. AASHTO Standard: M 231, Weighing Devices Used in the Testing of Materi
4、als 2.2. ASTM Standards: C670, Standard Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials E29, Standard Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications 2.3. Other Document: NCHRP Web-Only Document 164: Pre
5、cision Estimates of AASHTO T 265: Laboratory Determination of Moisture Content of Soils 3. TERMINOLOGY 3.1. Definition: 3.1.1. moisture or water content of a soilthe ratio, expressed as a percentage, of the mass of water in a given mass of soil to the mass of the solid particles. Practical applicati
6、on is to determine the mass of water removed by drying the moist soil to a constant mass in a drying oven controlled at 110 5C (230 9F) and to use this value as the mass of water in the given soil mass. The mass of soil remaining after oven-drying is used as the mass of the solid particles. 4. APPAR
7、ATUS 4.1. Drying OvenThermostatically controlled, preferably of the forced-draft type, capable of being heated continuously at a temperature of 110 5C (230 9F). 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicabl
8、e law.TS-1a T 265-2 AASHTO 4.2. BalanceThe balance shall have sufficient capacity, be readable to 0.1 percent of the sample mass, or better, and conform to the requirements of M 231. 4.3. ContainersSuitable containers made of material resistant to corrosion and not subject to change in mass or disin
9、tegration on repeated heating and cooling. Containers shall have close-fitting lids to prevent loss of moisture from samples before initial weighing and to prevent absorption of moisture from the atmosphere following drying and before final weighing. One container is needed for each moisture content
10、 determination. 5. TEST SAMPLE 5.1. Select a representative quantity of moist soil in the amount indicated in the method of test. If no amount is indicated, the minimum mass of the sample shall be in accordance with the following table: Maximum Particle Size Minimum Mass of Sample, g 0.425-mm (No. 4
11、0) sieve 10 4.75-mm (No. 4) sieve 100 12.5-mm (1/2in.) 300 25.0-mm (1 in.) 500 50-mm (2 in.) 1000 6. PROCEDURE 6.1. Weigh a clean, dry container with its lid and place the moisture content sample in the container. Replace the lid immediately and weigh the container, including the lid and the moist s
12、ample. Remove the lid and place the container with the moist sample in the drying oven maintained at a temperature of 110 5C (230 9F) and dry overnight (15 h minimum) or dry until the mass loss of the sample after 1 h of additional drying is less than 0.1 percent (constant mass) (Notes 1 and 2). Imm
13、ediately upon removal from the oven, place the lid and allow the sample to cool to room temperature. Weigh the container including the lid and the dried sample (Notes 3 and 4). Note 1 In cases where there is doubt concerning the adequacy of overnight drying, drying should continue until constant mas
14、s is achieved. Samples of sand may often be dried to constant mass in a period of several hours. Since dry soil may absorb moisture from wet samples, dried samples should be removed before placing wet samples in the oven. Note 2Oven-drying at 110 5C (230 9F) does not result in reliable moisture cont
15、ent values for soil containing gypsum or other minerals having loosely bound water from hydration or for soil containing significant amounts of organic material. Reliable moisture content values for these soils can be obtained by drying in an oven at approximately 60C (140F), or by vacuum desiccatio
16、n at a pressure of approximately 10 mm Hg and at a temperature not lower than 23C (73F). Note 3A container without a lid may be used provided the moist sample is weighed immediately after being taken, and provided the dried sample is weighed immediately after being removed from the oven or after coo
17、ling in a desiccator. Note 4Moisture content samples should be discarded and should not be used in any other tests. 7. CALCULATION 7.1. Calculate the moisture content of the soil as follows: 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplicati
18、on is a violation of applicable law.TS-1a T 265-3 AASHTO ( )( )( )( )122mass of moisture100 100mass of oven-dry soil = = cWWwWW(1) where: w = moisture content, percent; W1= mass of container and moist soil, g; W2= mass of container and oven-dried soil, g; and Wc= mass of container, g. 7.2. Calculate
19、 the percent of moisture content to the nearest 0.1 percent. 8. PRECISION AND BIAS 8.1. PrecisionCriteria for judging the acceptability of determining percentage of moisture content of soil using T 265 are given in Table 1: 8.1.1. Single-Operator Precision (Repeatability)The figures in Column 2 of T
20、able 1 are the standard deviations that have been found to be appropriate for percent moisture content of the materials in Column 1. Two results obtained in the same laboratory, by the same operator using the same equipment, in the shortest practical period of time, should not be considered suspect
21、unless the difference in the two results exceed the single-operator limits given in Table 1, Column 3. 8.1.2. Multilaboratory Precision (Reproducibility)The figures in Column 2 of Table 1 are the standard deviations that have been found to be appropriate for the percent moisture content of the mater
22、ials in Column 1. Two results submitted by two different operators testing the same material in different laboratories shall not be considered suspect unless the difference in the two results exceeds the multilaboratory limits given in Table 1, Column 3. Table 1Precision Estimates for T 265 Material
23、 and Type Index Standard Deviationa(Percent) Acceptable Range of Two Resultsa(Percent) Single-operator precision: Coarse aggregate-soil blend Fine aggregate-soil blend 0.05 0.16 0.1 0.5 Multilaboratory precision: Coarse aggregate-soil blend Fine-aggregate-soil blend 0.12 0.21 0.3 0.6 aThese values r
24、epresent the 1s and d2s limits described in ASTM C670. Note 5The precision estimates given in Table 1 are based on the analysis of test results from an AMRL interlaboratory study (ILS). The ILS data consisted of results from 26 to 29 laboratories that tested three replicates of four different aggreg
25、ate-soil blends each having about 7 percent passing a No. 200 sieve. The average moisture contents of the test specimens ranged from 3 to 6 percent. The details of this analysis are in NCHRP Web-Only Document 164. 8.2. BiasNo information can be presented on the bias of the procedure because no comparison with the material having an accepted reference value was conducted. 2015 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.
