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From this, the dry density could be determined by simply measuring the weight of the soil before and after compaction, calculating the moisture content, and furthermore calculating the dry density. Ralph R. Proctor went on to teach at the University of Arkansas. In 1958, the modified Proctor compaction test was developed as an ASTM standard.
This test is used by Caltrans for pavement design, replacing the California bearing ratio test. Soil compaction tests Standard Proctor (ASTM D698), Modified Proctor (ASTM D1557), and California Test 216. These tests are used to determine the maximum unit weight and optimal water content a soil can achieve for a given compaction effort.
The most commonly used laboratory test is called the Proctor compaction test and there are two different methods in obtaining the maximum density. They are the standard Proctor and modified Proctor tests; the modified Proctor is more commonly used. For small dams, the standard Proctor may still be the reference. [5]
The test uses a thick-walled sampling tube, with an outside diameter of 5.01 cm (2 in) and an inside diameter of 3.5 cm (1.375 in), and a length of at least 60 cm (24 in). The sampling tube is driven into the ground at the bottom of a borehole by blows from a hammer with a mass of 63.5 kg (140 lb) falling a distance of 75 cm (30 in). The sample ...
The rebound reading will be affected by the orientation of the hammer: when used oriented upward (for example, on the underside of a suspended slab), gravity will increase the rebound distance of the mass, and vice versa for a test conducted on a floor slab. Schmidt hammer measurements are on an arbitrary scale ranging from 10 to 100.
The liquid limit test is defined by ASTM standard test method D 4318. [4] The test method also allows running the test at one moisture content where 20 to 30 blows are required to close the groove; then a correction factor is applied to obtain the liquid limit from the moisture content. [5]
If the soil has 5–12% by weight of fines passing a #200 sieve (5% < P #200 < 12%), both grain size distribution and plasticity have a significant effect on the engineering properties of the soil, and dual notation may be used for the group symbol.
High strain dynamic testing consists of estimating soil resistance and its distribution from force and velocity measurements obtained near the top of a foundation impacted by a hammer or drop weight. The impact produces a compressive wave that travels down the shaft of the foundation.