TREATMENT OF EXPANSIVE SOILS: A LABORATORY STUDY

Excessive heave and settlements that are associated with the volume changes of expansive soils can cause considerable distress to civil engineering structures. Even structures such as highway embankments and roadways that are generally insensitive to small vertical movements are subject to high maintenance costs if constructed on expansive soils. It has been reported that a small amount of settlement or heave over a short length of road is intolerable for high-speed highways. A laboratory investigation to reduce the swelling properties of the expansive soils found in Nasr City, a satellite community of Cairo, Egypt, is reported in this paper. Three techniques to reduce the amount of swelling and the associated swelling pressures were studied: (a) complete saturation of the expansive soil specimens after they had been compacted at various initial water contents, (b) mixing of the expansive soil with various proportions of sand to study the effect of grain size distribution on the swelling potential, and (c) use of various salt concentrations of the pore fluid to show its effectiveness in reducing the overall swelling property. All three techniques were found to be effective in reducing the swelling behavior of soils to various degrees as discussed in this paper.