The effect of pH and electrical conductivity of the soaking fluid on the collapse of a silty clay

Different fluids can permeate the soil collapsing at various levels of severity depending on their physicochemical characteristics. This work evaluated the effect of pH and electrical conductivity (ECf) of different soaking fluids on the collapsible behavior of a lateritic silty clay. Double and single oedometer tests were performed using four chemically distinct soaking fluids (water, leachate and two laboratory solutions, one alkaline and one acid). The collapse index (I) was evaluated according to two criteria. In addition, physical-chemical analysis of the soil and measurements of pH and ECf were done. According to the results, the soil is collapsible for the four soaking fluids. No single relationship was found between fluid pH and collapse index, although, the highest values of collapse index were found in the tests soaked with alkaline and acid solutions. Finally, a unique direct relationship was found between the collapse index and the ECf, that is, the higher this parameter, the higher the collapse index value.