For samples of this size, place the sample on the canvas or a clean sheet of paper. Mix it thoroughly with a trowel, form it into a conical shape, and then flatten it with the trowel. Using the trowel, divide the sample into quarters, and discard two diagonally opposite quarters, as shown in figure 15-25. Remix the remaining material, and repeat the process until the sample is the size needed for the test.

In soil testing, the Navy follows procedures laid down by the American Society for Testing Materials (ASTM). Generally speaking, a complete soil test proceeds according to the following steps:

1. Determine the moisture content of representative samples. (This is preceded, of course, by the extraction of representative samples.)

2. Perform a mechanical analysis of the sample to determine the sizes of soil particles (or

grains) and the distribution of sizes; this means the percentage of each size contained in the whole mass.

3. Determine the specific gravity of representative samples. The specific gravity of a substance is expressed in terms of the ratio of the weight of a given volume of the substance to the weight of an equal volume of water. A cubic foot of water weighs 62.43 lb. For soil, determine the absolute specific gravity; by this we mean determine the ratio of the weight of a dense volume (volume exclusive of air spaces) to the weight of an equal volume of water. A cubic foot of dry sand, for example, weighs about 100 lb. With air exhausted, however, a cubic foot of sand weighs about 165.44 lb. Therefore, the specific gravity of sand equals 165.44 divided by 62.43, or about 2.65.

4. If the soil is clay or a similar fine-grained soil, determine the Atterberg limits. Over a certain range of moisture content, a fine-grained soil remains plastic. A reduction below the bottom of the range causes the soil to become semisolid; an increase above the range causes it to become fluid. The upper moisture content is called the liquid limit; the lower is called the plastic limit.

5. Compaction testing is used to determine the moisture-density relationships; or, in other words, to determine what moisture content results in maximum compaction for a given compactive effort. Compaction testing is not included in this TRAMAN but will be discussed at the EA2 level.

6. Field control testing is used to determine (1) the field moisture content (with an eye to reducing or increasing it to the optimum, if feasible) and (2) the point at which the specified density has been obtained by compaction. Field control testing is not included in this TRAMAN but will be discussed at the EA2 level.