Stress–Strain–Strength and Hydraulic Performance of Microfine Cement Grouted Sands

Abstract

An experimental investigation was conducted in order to evaluate the effectiveness of six new microfine cement grouts obtained by pulverizing three ordinary cements with different chemical composition. Both consolidated-undrained with pore pressure measurement (CU-PP) triaxial compression and hydraulic conductivity tests were conducted on each grouted sand specimen. Grouting increased the stiffness and reduces the hydraulic conductivity of the sands. The shear-strength behavior of the grouted sands was described satisfactorily by the Mohr-Coulomb failure criterion. The bleed capacity of the injected suspensions was a good indicator of the grouting-induced mechanical and hydraulic behavior improvement. Grouting with stable [water to cement ratio (W/C)=1] microfine cement suspensions was superior to grouting with coarser cements at W/C=1, yielded hydraulic conductivity values as low as 5.5×10−8 cm/s, added cohesion reaching 2 MPa and, on the average, increased the initial modulus of elasticity by 10 times, reduced failure deformation by 5 times, and increased the peak strength by 8.5 times. Grouting with unstable microfine cement suspensions provided measurable, but not as pronounced, improvement. A change in stress–strain–strength behavior of grouted sands, associated with the beginning of cementitious bonds breakage, was systematically observed at low axial deformation (0.2%–0.7%).