AASHTO T 99

Description / Abstract: These methods of test are intended for determining the relation between the moisture content and density of soils compacted in a mold of a given size with a 2.5-kg (5.5-lb) rammer dropped from a height of 305 mm (12 in.). Four alternate procedures are provided as follows:

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  Method A—A 101.60-mm (4-in.) mold: Soil material passing a 4.75-mm (No. 4) sieve (see Sections 4 and 5);
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  Method B—A 152.40-mm (6-in.) mold: Soil material passing a 4.75-mm (No. 4) sieve (see Sections 6 and 7);
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  Method C—A 101.60-mm (4-in.) mold: Soil material passing a 19.0-mm (3/4-in.) sieve (see Sections 8 and 9); or
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  Method D—A 152.40-mm (6-in.) mold: Soil material passing a 19.0-mm (3/4-in.) sieve (see Sections 10 and 11).

The method to be used should be indicated in the specifications for the material being tested. If no method is specified, the provisions of Method A shall govern.

This test method applies to soil mixtures that have 40 percent or less retained on the 4.75 mm- (No. 4) sieve, when Method A or B is used and 30 percent or less retained on the 19.0-mm (3/4-in.) sieve, when Method C or D is used. Material retained on these sieves shall be defined as oversized particles (coarse particles).

If the test specimen contains oversized particles, dry density and moisture corrections must be made in accordance with Annex A1. The person or agency specifying this method may specify a minimum percentage of oversized particles above which a correction must be applied. If no minimum percentage is specified, correction for the oversized particles shall be applied to material containing more than 5 percent by weight of oversized particles.

If the specified oversized particle maximum percentage is exceeded, other methods of compaction control must be used.

Note 1—One method for the design and control of the compaction of such soils is to use a test fill to determine the required degree of compaction and a method to obtain that compaction. Then use a method specification to control the compaction by specifying the type and size of compaction equipment, the lift thickness, and the number of passes.

The following applies to all specified limits in this standard: For the purposes of determining conformance with these specifications, 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.

The values stated in SI units are to be regarded as the standard.