Protective system for buried infrastructure using recycled tire rubber-filled cement mortars

With population growth and urbanization, the space available for installation of civil infrastructure is rapidly decreasing. There is need for a more efficient use of underground space, which involves the construction of tunnels and other underground structures. Due to space constraints, many underground infrastructure projects in the future will be located in rock/soil with time-dependent behavior and/or under high overburden pressure. A deformable supporting system that can serve as a buffer layer for protecting tunnel linings and buried structures from time-dependant deformations of the excavated rock/soil will therefore be needed. This study investigates the possible use of cement mortars containing crumb tire rubber to develop a flexible interface material for such applications. The effects of the water/cement ratio (w/c) ratio, rubber content and particle size on the mechanical properties of the mortars were studied using uni-axial and tri-axial compression tests. A statistical factorial experimental was designed to obtain response surfaces for the parameters under study. The findings of this research suggest that cement mortars containing ground tire rubber have superior ductility and may be used to accommodate deformations around tunnel linings, pipelines, and other buried infrastructure.