Behavior of zeolite-cement grouted sand under triaxial compression test

Permeation grouting with cement agent is one of the most widely used methods in various geotechnical projects, such as increasing bearing capacity, controlling deformation, and reducing permeability of soils. Due to air pollution induced during cement production as well as its high energy consumption, the use of supplementary materials to replace in part cement can be attractive. Natural zeolite (NZ), as an environmentally friendly material, is an alternative to reduce cement consumption. In the present study, a series of consolidated undrained (CU) triaxial tests on loose sandy soil (with relative density Dr = 30%) grouted with cementitious materials (zeolite and cement) having cement replacement with zeolite content (Z) of 0%, 10%, 30%, 50%, 70% and 90%, and water to cementitious material ratios (W/CM) of 3, 5 and 7 has been conducted. The results indicated that the peak deviatoric stress (qmax) of the grouted specimens increased with Z up to 50% (Z50) and then decreased. The strength of the grouted specimens reduced with increasing W/CM of the grouts from 3 to 7. In addition, by increasing the stress applied on the grouted specimens from yield stress (qy) to the maximum stress (qmax), due to the bond breakage, the effect of cohesion (c′) on the shear strength reduced gradually, while the effect of friction angle (φ′) increased. Furthermore, in some grouted specimens, high confining pressure caused breakage of the cemented bonds and reduced their expected strength.