Study on a novel chemical slurry and the mechanical behavior of cemented sand

Abstract

To enhance the strength and stability of the fine sandy soil in underground engineering construction, a novel chemical slurry was studied. Series of laboratory tests were performed to determine the effect of each component on the rheological properties of grout (e.g. viscosity, gel time and plastic strength). The relationship of the penetrability of grout in sand with different densities was explored by the falling-head permeability test. To assess the performance of cementation, the cemented sand specimens were prepared in the laboratory by hand mixing of grout and loose sand. A range of unconfined uniaxial compression tests, split tensile tests and direct shear tests were performed to determine the effect of several vital factors (e.g. the curing time, grout mix ratio and water content) on the mechanical properties of the cemented sand. As revealed from the results of the experiment, the slurry pertains to Newton fluid in the initial stage, which exhibits lower initial viscosity (2 mPa·s), controllable gel time (5–20 min) and higher plastic strength (35 kPa). In terms of the cemented sand, the maximal cohesion and friction angle is 403.8 kPa and 65°; the biggest compressive strength and tensile strength is 3.68 and 0.37 MPa. The slurry can enhance the strength and stiffness of the loose sand significantly, whereas the degree of improvement is dependent of the grout mix ratio and water content of cemented sand.