Universal Compression Index Equation

An expression is developed empirically which relates virgin compression index with instantaneous zero-air-voids curve slope, and which is applicable to saturated sedimented fine grain soils of a given value of specific gravity regardless of stress history. It is based on: (1)The assertion that field consolidation curves are relatively parallel for a given value of void ratio; and (2)on the fact that the consolidation processes of saturated fine-grain soils having the same specific gravity can be characterized by a single zero-air-voids curve. Consolidation test data, which were used to develop the expression, were obtained from U.S. Army Corps of Engineers district and division offices in the United States. An experiment is currently underway using a slurry-consolidometer to obtain field consolidation test results on pure clay specimens, the data of which is hoped will yield a more accurate expression for compression index.