AN INVESTIGATION INTO CURRENT PROCEDURES FOR ESTIMATING HEAVE POTENTIAL IN CLAYS

Abstract

An investigation into current procedures for estimating heave potential in clays Several low-cost housing developments in South Africa are suffering major structural failures due to heaving clays. Despite geotechnical investigations and various precautionary measures, this remains an on-going trend. The aim of this study was to review the current procedures used in South Africa to estimate heave potential in view of either improving the current procedures or suggesting alternatives. To this end, the research question was as follows: Are the current procedures used in South Africa to estimate heave potential acceptable? In this context, the most popular procedure used in South Africa, van der Merwe’s method, was broken into parts and studied. The research question was answered in the variance of laboratory results obtained from seven leading commercial laboratories which proved that reliable input parameters to van der Merwe’s empirical method are not obtainable. Typically the Atterberg limits and clay fraction results varied significantly producing heave potential classifications that do not accurately reflect the soil characteristics of the samples studied. On this basis, an investigation into methods of estimating heave potential, which are not considered in current South African codes of practice, were studied in order to provide a foundation for future research. A weighed system is proposed to judge the heave potential of soils using various prediction models as a foundation for future research.