Shear strength of microfine cement grouted sands

Unconsolidated–undrained (single and multi-stage) triaxial compression tests were conducted to evaluate the shear strength of microfine cement grouted sands. Microfine cements of three different types were obtained by pulverising ordinary cements produced in Greece. Multi-stage triaxial compression tests can be used dependably for determination of the shear strength parameters of cement grouted sands. It has been observed that the Mohr–Coulomb failure criterion represents adequately the behaviour of the grouted sands. Grouting with microfine cement suspensions improves the strength of sands significantly, and the improvement is primarily controlled by the water-to-cement (W/C) ratio of the suspensions. The positive effect of microfine cement grouting on the shear strength of sands is mainly the addition of cohesion, which is substantial even at a distance of 1·2 m from the injection point. Grouting with suspension, using W/C = 1 provides the sand with cohesion of about 2·6 MPa. The shear strength parameters vary with axial strain, and cohesion attains a maximum value well before failure.