The effects of environmental pollution on cyclic swell and shrink behavior of Na-bentonite clay

Abstract

This paper investigates the environmental pollution effects such as saline water, kerosene and sanitary leachate of cyclic wetting and drying on swell and shrink behavior of compacted Na-bentonite clay. First of all, optimum moisture content of Na-bentonite clay was determined by using standart compaction test with distilled water. Then, two samples prepared at optimum moisture content were; placed in the oedometer test apparatus. Distilled water, saline water, kerosene and sanitary leachate were added to oedometer cell to determine swell and shrink behavior of compacted Na-bentonite clay under environmental conditions. The one dimensional free swell tests were performed under 7 kPa. The swelling pressure tests were performed by the pressures in small increments to prevent swelling. This was continued until swelling pressure was prevented. While the distilled water has the highest free swell, saline water has the lowest free swell among them. Likewise, the distilled water has the highest swelling pressure, saline water has the lowest swelling pressure among them. The experimental results showed that after each cycle, swelling and shrinking behavior of compacted Na-bentonite clay were decreased. The clay microstructure after cyclic wetting and drying was also investigated.