Volume 4, Issue 2 (June 1981)
The Expansion Index Test
The Expansion Index Test was developed a decade ago for laboratory determination of the expansion potential of soils. The initial conditions in this test are specified to provide a specimen that will produce a measurable amount of expansion with a fairly wide range and sensitivity in a 24 h period. Thus, the test provides an index to the expansion potential of soils. Thirteen soils were used in a correlation study between the expansion index and other indices of soil expansion potential. Five of these soils were used in a detailed study of the influence of the initial degree of saturation. Three of the soils were sent to geotechnical engineering firms to determine the reproducibility of test results. This study showed a good deal of scatter but on the order of similar studies for other tests. Respondents to a survey generally agreed that the Expansion Index Test produces a reliable index to soil expansion potential.