Enhancing Soil Shear Parameters with Polymer-Gypseous Composite Material Using an Integrated Approach

Abstract

This study has attempted to enhance and characterise the shear strength of sandy clay soil mixed with 50% gypsum through an integrated treatment combining petrochemical and freezing techniques. The soil specimens used in this paper have been taken from a 0.5-1.0 m depth. The disturbed soil samples have been packed in bags weighing 60-70 kg and then transported to the lab. First, the petrochemical technique has been applied separately using polypropylene with various weight percentages (dry weight) of the gypseous soil and different aspect ratios of liquid polymer to represent composite materials in two phases (drying and immersion) for a specified period. Then, the freezing approach has been implemented at -3 °C, -7 °C and -10 °C. Finally, the proposed integrated method has been performed based on a combination of the petrochemical approach and freezing for all three methods. The shear stress of unsaturated soil has been measured using direct shear tests and compared with the treated samples. The integrated approach had the best results, in particular the 15% polymer under freezing at -7 °C for gypseous soil. These results indicate that this composite material is useful for the improvement of shear behaviours due to its curing time and petrochemical content.