Compressibility Characteristics of Gypseous Sandy Soils

Abstract

Abstract Soils containing gypsum as a cementing agent are affected considerably when subjected to changes in water content. Seepage through sandy gypseous soil causes serious damage to foundations built on such soils. A testing program was conducted on undisturbed soil specimens with three different gypsum contents to study the compressibility characteristics of such soils. The testing program included the following tests: standard consolidation, collapse, double oedometer, leaching, leaching collapse, and permeability. The results revealed that the gypseous soil tested was a highly cemented sand whose compressibility depended on gypsum content. The behavior of this soil exhibited significant changes upon addition of water, especially when the process was accompanied by a continuous flow of water. The leaching process caused an increase in the value of the Compression Index. Furthermore, the soil exhibited what could be defined as “delayed compression,” whose rate was dependent on stress level and which increased upon leaching. The soil was found to be a “collapsible” soil, whose collapsibility increased significantly with leaching.