Electronic Thesis and Dissertation Repository

Degree

Master of Engineering Science

Program

Civil and Environmental Engineering

Supervisor

Shang, Julie Q.

Abstract

Chemical grouting has been used in engineering projects for decades. The primary objectives of chemical grouting in geotechnical engineering projects are to increase the soil strength, to decrease the soil permeability, and to control deformations of in-situ soil. In the design and applications of chemical grouting, laboratory testing of chemical grouted samples is an important step for the feasibility assessment.

The advantages of sodium silicate grout include high penetrability, flexible set times, and environmentally friendly, which makes it one of the most employed grouts in applications. Recently, an innovative sodium silicate, which has the silica to alkali ratio of 4.5 (S45), was designed and manufactured by National Silicates Inc. In this research, the performance of S45 grout on chemical stabilization of quartz sand was investigated through three laboratory tests, i.e., unconfined compressive strength test, wetting-drying durability test, and hydraulic conductivity test. The influence of four variables, i.e., silicate concentration, curing time, setting agent, and gel additive CaCl2 on the behavior of silicate grouted sand was studied. The Environmental Scanning Electron Microscopy (ESEM) analysis was conducted to manifest the working mechanism of chemical grouting on sand. Moreover, the chosen tests, i.e., unconfined compressive strength test, and wetting-drying durability test, on conventional NS silicate grouted sand samples were conducted in parallel for comparison. The results show that the innovative S45 silicate has significantly better performance against conventional NS silicate on chemical grouting, in terms of strength gain and durability of silicate grouted sand.

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