Micromechanism of the diffusion of cement-based grouts in porous media under two hydraulic operating conditions: constant flow rate and constant pressure

Abstract

Cement-based grout has been widely used in various civil engineering applications. The diffusion of cement-based grouts in porous media is an important issue in soil sealing and the estimate of grouting. To better understand the effects of grouting parameters on the viscosity of slurry, the porosity of an injected media and the pressure variations under constant flow rate and constant pressure conditions, a series of laboratory tests were conducted on the fractal characteristics of sand in a column. Additionally, different grouting flow rates and pressures, water/cement ratios and mass fractal dimensions were studied. The experimental results show the following responses: (1) the variation in the diffusion pressure of the slurry under the condition of a constant pressure is clearly different from that under constant pressure. (2) There is a strong correlation between the porosity and water/cement ratio regardless different hydraulic operating conditions, whereby a reduction or increase in the water/cement ratio control the range of the slurry diffusion. (3) Regardless of the hydraulic operating conditions, the grouting pressure presents a nonlinear decreasing law with the increase in distance from the grouting source. (4) An excessive flow rate or pressure is not conducive to the diffusion of slurry.