Volume Change and Strength Behavior of Expansive Clay Stabilized with Scrap Tire Rubber

Expansive soils in semi-arid climates are well known to cause detrimental damages in the form of cracks and differential movements of the civil engineering structures. In quest for economical and efficient methods for mitigation of swelling soils, there is a growing interest in using waste materials with a secondary aim of recycling the material. This study concentrated on using scrap tire rubber (STR) powder as a stabilizer for improving the locally available expansive soil. Using the scrap tire rubber in soil stabilization can be a feasible solution for recycling this waste material, hence reducing the environmental problems, as discarded waste tires impose a major environmental pollution. An experimental program was conducted to evaluate the mechanical characteristics of the expansive soil, including swell-shrinkage potential, hydraulic properties, and strength characteristics. Different percentages of STR (10%, 20%, and 30%) were mixed with natural expansive soil to evaluate its influence on physical and mechanical properties. The experimental findings displayed that 30% STR reduced the plasticity and swell potential considerably, while no change in compressibility parameters was recorded. The STR inclusion has been most effective in rendering the shrinkage potential, which causes settlement of light structures along their outer perimeter causing differential movements. Finally, the results show that modification of expansive soils using STR might be an effective technique in enhancing the soil characteristics against swelling-shrinking potential of subsoils on which roads and light weight structures are constructed. Therefore, the scrap tire rubber waste has a potential for stabilizing expansive soils, thus giving a two-fold advantage in enhancing a problematic soil and also resolving the problem of disposal of waste by recycling it. On the other hand, the results of unconfined compression, flexural strength and California Bearing Ratio tests demonstrated that the amounts and particle size of STR could not improve the strength properties, and that further research is recommended using different sizes and percentages of the scrap tire rubber waste. Keywords: Expansive soil, scrap tire rubber and stabilization.