Effects of polyurethane foam on the behaviour of collapsible soils

Abstract

Collapsible soils such as gypseous soil are problematic in geotechnical engineering because their volume changes significantly upon saturation. Foundations constructed on gypseous soil undergo sudden and large settlement if the underlying soil experiences unanticipated moisture. The present study aims to improve the gypseous soil behaviour so that it can be used to support shallow foundations. To understand the mechanisms of stabilisation better, a laboratory study is performed to evaluate how polyurethane foam in different amounts influences the volumetric strain, collapse potential and mechanical behaviour of gypseous soil. Physical models of a footing on treated gypseous soil with polyurethane foam are examined to determine the effective treatment zone. Based on the obtained results, 3% polyurethane foam can be recommended to improve the gypseous soil behaviour; the particular reason is its effectiveness in decreasing the change in volumetric strain and collapse potential. The present study develops a theoretical approach that depends on a non-dimensional parameter to predict the ultimate bearing capacity for a footing on the surface of treated gypseous soil using the existing conventional theories.