Abstract: Rubber-sand mixture (RSM) has long been recognized as a light weight and energy absorbing material with widely usage in civil engineering. Shear strength of RSM usually decreases with inclusion of rubber particles. As geogrid is usually used to improve the shear strength of granular materials, it is of great interesting to find out how geogrid affect the strength of RSM when RSM is reinforced by geogrid. Triaxial tests were carried out on dry RSMs to study the influence of reinforcing geogrid layers on the strength parameters, such as peak deviatoric stress, pseudo cohesive strength and internal friction angle. Five rubber contents (0%, 10%, 20%, 30% and 40%) and three confining pressures (50 kPa, 100 kPa, 200 kPa) were taken into accounted in tests. Test results indicate that peak deviatoric stress, pseudo cohesive strength and internal friction angle of RSMs reinforced by geogrid are significantly improved comparing to those of RSMs without geogrid. These parameters increase with the increase of the number of geogrid reinforcement layers and with the decrease of confining pressure. The reinforcing effect on strength of RSM by geogrid reaches a peak when the rubber content is 20%. The strength recovery coefficients of geogrid reinforced RSMs exhibit linear relations with the reinforcement density of geogrid, and can be estimated well by the empirical curves of this study.

Key words: rubber sand mixture (RSM), geogrid reinforcement, strength characteristics, triaxial tests, reinforcement density