The specific procedures that you should follow when testing for these fine materials can be found in ASTM C 117 and in NAVFAC MO-330. Briefly, you oven-dry and weigh a sample of the aggregate. Then the dried sample is brought to suspension in water and is carefully poured through a nest of sieves (No. 16 and No. 200) until the wash water is clear. Finally, the material remaining on the sieves is oven-dried and weighed. The percent of material finer than the No. 200 sieve is then calculated using the following formula:

The method described above is accurate, but time-consuming. When time is critical and less accurate results are acceptable, you can place a 1,000-gram sample into a quart mason jar to a depth of about 2 inches. Then fill the jar three-fourths full of water, shake the mixture vigorously, and allow it to stand for 1 hour. The silt and clay will form a layer at the top of the sand. If the layer is more than 1/8 inch thick, the material has more than 3 percent fines and should be washed before using.

Test for Clay Lumps and Friable Particles. This test is performed on the material remaining after you determine the material finer than the No. 200 sieve. The size of samples needed and the specific test procedures that you should use are in ASTM C 142 or in NAVFAC MO-330. Spread the sample in a thin layer on the bottom of a flat pan and cover it with distilled water. After about 24 hours, you break up all particles by crushing them between the fingers. Next, you remove the broken clay lumps and friable particles by wet sieving over the appropriate one of the following sieves: aggregateNo. 20; No. 4 to 3/8 inchNo. 8; over 3/8 inchNo. 4. Oven-dry and weigh the material retained. Then you can calculate the percentage of clay lumps and friable particles using the following equation:

P= percent of clay lumps and friable particles

W 1 = original weight of test sample

W 2 = weight of retained sample after wet sieving and drying