AbstractAn 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%).

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