Performance of Microfine Cement Grouted Sands Under Quick Loading Conditions

An experimental investigation was conducted to evaluate the influence of factors pertinent to the suspension and the sand on the effectiveness of microfine cement grouts under quick loading conditions, that is, conditions, where the grouted soil mass is loaded at a rate which is much faster than the rate of pore water pressure dissipation and total stress behavior may be of interest. Unconfined compression and unconsolidated-undrained triaxial compression tests were conducted on grouted sand specimens obtained by injecting suspensions of 12 cements with three water to cement (W/C) ratios into four sands with different grain sizes. A Mohr–Coulomb type linear failure criterion describes satisfactorily the shear strength behavior of cement grouted sands in total stress terms. The values of the activated shear strength parameters generally increase with increasing axial deformation during loading. Grouting with suspensions having W/C = 1 yields unconfined compression strength of grouted sands up to 9 MPa, adds cohesion to the sands reaching 1.7 MPa, increases by 6–14 times the initial modulus of elasticity, reduces by 5–10 times the failure deformation and may increase up to 20% the angle of internal friction of the sands. The stress–strain–strength behavior of sands grouted with suspensions having W/C = 1 is similar to that of cement suspension sediments with the same W/C ratio, whereas the behavior of sands grouted with suspensions having W/C = 3 is similar to that of the clean sands.