Soil texture are the medium-sized (0.05 - 0.002 mm) and sink to the bottom of the cylinder after the sand. Clay particles are the smallest (<0.002 mm) and separate out above the silt layer. Measurements are taken using a soil hydrometer. A soil hydrometer measures that relative density of liquids (density of a liquid to the density of water). The hydrometer is lowered into the cylinder containing the soil mixture at different times, forty-five seconds to measure sand content, one and a half hours to measure silt content and between six and twenty-four hours (depending on the protocol used) to measure clay.
Sand equivalent test Sand equivalent test The sand equivalent test quantifies the relative abundance of sand versus clay in soil. It is measured by standardized test methods such as ASTM D2419, AASHTO T176, and EN 933-8. The test is used to qualify aggregates for applications where sand is desirable but fines and dust are not. A higher sand equivalent value indicates that there is less clay‐like material in a sample. During the test, material from the test specimen that can pass through a No. 4 sieve is mixed with solutions of calcium chloride, formaldehyde and glycerin in a cylinder. The content is then