The determination of material finer than a 75-μm (No.
200) sieve in aggregate by washing is conducted by the AASHTO T 11-05/ASTM C 117-13 test method. Clay and other
aggregate particles are dispersed by
the wash water and removed from the aggregate during the test.
Two procedures are described in the standard;
- Procedure A: where only water is used for the washing operation.
- Procedure B: where a wetting agent is used to assist the loosening of the material during the washing
Procedure A is generally adopted unless otherwise specified.
Step 1: Sampling
Aggregates are sampled in accordance with AASHTO T 2. In most instances, the same test
will be subjected to sieve analysis test according to AASHTO T 27; in which case, applicable requirements of
AASHTO T 27 shall be complied with. Otherwise, the mass of the dried test sample shall conform with
the requirements given in table below.
Nominal Maximum Size
Minimum Mass, g
|4.75 mm (No. 4) or smaller
|9.5 mm (3/8 in.)
|19.0 mm (3/4 in.)
|37.5 mm (11/2 in.) or larger
For nominal maximum size of the aggregate to be tested which are not listed above, the next larger size listed
shall be used to determine sample size.
Dry the test sample to constant mass at a temperature of 110 ± 5°C (230 ± 9°F). Determine
the mass (B) to the nearest 0.1 percent of the mass of the test sample.
Place the dry test sample in the
container and add
sufficient water to cover it. Any suitable dispersing agent, such as liquid dishwashing detergents, that will
promote separation of the fine materials may be added during this stage. Agitate the sample to result in
complete separation of all particles finer than
the 75-μm (No. 200) sieve from the coarser particles, and to bring the fine material into suspension. Pour the
wash water containing the suspended and dissolved solids over the nested sieves, arranged with the coarser
sieve on top.
Add a second charge of water to the sample in the container, agitate, and decant as before
and repeat this until the wash water is clear.
Dry the washed aggregate to constant mass at a temperature of 110 ± 5°C (230 ± 9°F) and
determine the mass (C) to the nearest 0.1 percent of the original mass of the sample.
Calculate the amount of material passing a 75-μm (No. 200) sieve by washing as follows: