Improvement of expansive soil by microwave irradiation

Abstract

This paper presents an experimental investigation of the use of microwave irradiation to improve the characteristics of expansive soils. The expansive soil samples were subjected to microwave heating in an industrial microwave oven, and were followed by analysis of the soil characteristics such as the specific gravity, liquid and plastic limit, free swelling ratio, vertical free swelling strain and swelling pressure. X-ray diffraction was also used to determine the mineral composition of the samples. Experimental results showed that the microwave irradiation induces both a rapid increase in the soil temperature and a significant change in the soil mineral content. With the increase in the power level, we observed first an increase in the specific gravity up to a peak, which was followed by a decrease. For the other characteristics such as the liquid and plastic limit, the free swelling ratio, the vertical free swelling strain and the swelling pressure, their values were observed a decrease with the increase in the power level. The change in the soils characteristics could be attributed to the impact of the irradiation on the expulsion of the interlayer structure water and on the change of soil mineral content or structure.