Geotechnical Properties of Rubber Reinforced Cemented Clayey Soil

This paper focuses on the effect two forms of waste rubber tyres of granulate (R-g) and fibre (R-f) categories on the compaction-strength-consolidation-swell-durability behaviour of uncemented/cemented clayey soil. The effect of incorporation of five proportions 0%, 2.5%, 5%, 7.5% and 10% R-g/R-f (by weight of soil) and three proportions 0%, 3% and 6% cement (by weight of soil) was assessed. Reduction in maximum dry unit weight (gamma(max)) and optimum water content (omega(opt)) of clayey soil and cemented clayey soil was observed with the incorporation of ruuber granulates (R-g) and rubber fibres (R-f). Both unconfined compressive strength (UCS) and split tensile strength (STS) of the clayey soil were primarily controlled by the amount of cement and waste rubber tyres and it was found to be decreased with the enhancement in rubber content. But addition of R-g and R-f was found to improve the ductility and strain hardening behaviour of cemented clayey soil, prosperously under unconfined compression. Inclusion R-g was found to be ineffective to overshadow the brittleness of the cemented clayey soil subjected to tensile loads. The inclusion of higher rubber content had lowered the strength of cemented significantly. Decline in the California bearing ratio (CBR) value, swelling pressure (sigma(s)) and increment in the compression index (C-c) and weight loss during wet/dry cycles were observed with the incorporation of R-g and R-f in cemented clayey soil. The results of all performed tests were cross checked and compared with various Indian standards to reach at the optimum dose of R-g and R-f that can be added to cemented clayey soil for its possible applications in back filling, construction of embankment (for rural roads), sub-grade course, sub-base course and slide slope of canal. The form of waste rubber tyre i.e. R-g and R-f had significant effect on the geotechnical characteristics of cemented clayey soil. Overall, R-f had outperformed the R-g, considering all evaluated geotechnical properties. Maximum dose of R-g and R-f to be added in cemented clayey soil should not be more than 5% and 7.5%, respectively.