Anisotropic behavior of cement-grouted sand

Grouting sand with a microfine cement grout reduces its pore sizes and alters its pore structure. The sedimentation of cement particles in the soil adds prior to setting and the accumulation of bleed water in the upper portions of the pores introduces a preferred orientation and distribution in the resulting sands and an associated anisotropic behavior of the grouted soil. To quantify this phenomenon, Ottawa 20-30 sand was grouted with MC-500 grout at different water-to-cement ratios and then subjected to permeability, unconfined compression, and tensile tests. The results showed that the permeability of grouted sand can differ by as much as two orders of magnitude in orthogonal directions. Similarly, the unconfined compressive strength and the tensile strength of the grouted sand are directionally dependent and may differ by as much as 35% and 135%, respectively, for sand injected with 3:1 water-to-cement ratio grout and loaded in perpendicular directions.