Preferred orientation of pore structure in cement-grouted sand

The pore structure of a soil injected with a cement grout is a function of the water-to-cement ratio of the grout and the sedimentation behavior of the suspended particles. Prior to setting, the injected grout particles settle in the pore spaces between the sand grains and the bleed water accumulates at the tops of the pores; then, the settled cement particles react to form hydration products that preferentially connect the upper portions of the sand grains. Observations of hardened microfine cement grout with an environmental scanning electron microscope show that the pore structure of the neat grout is a function of the water-to-cement ratio and pore sizes range from less than 1μm to 30μm. Similar observations (by use of both an environmental scannings electron microscope and an optical microscope) of Ottawa 20-30 sand injected with either of three different microfine cement grouts show that the post grouting pore structure depends on the water-to-cement ratio of the grout and there is a preferred distribution of the cement particles in the pore space.