![]() Finally, some aspects related to the mechanism of soil improvement are discussed. Published results from physical model tests and in situ applications are also presented. All the grouting-induced effects on the soil behavior, which have been investigated by laboratory tests on small-sized soil elements, are reviewed, including the modifications to soil strength and stiffness under both static and seismic loading conditions, to soil compressibility and hydraulic conductivity. The grout delivery mechanisms through porous media are then explained, pointing out the crucial issues for practical application of CS grouting. This paper firstly describes the characteristics of CS grout, the gelation process and the main features of the behavior of the pure gelled material. CS grout is chemically and biologically inert and, when injected into a subsoil, it can form a silica gel and stabilize the desired soil layer, thus representing an attractive, environmentally friendly alternative to standard chemical grouting techniques. Many studies have recently been performed to investigate the potential of CS in improving the mechanical behavior of cohesionless soils and mitigating the risk of seismic liquefaction in urbanized areas. Besides, it also aims to provide references for optimizing the approaches of CS transport and promoting its responsible use in mitigating liquefaction.Ĭolloidal silica (CS) is a kind of nanomaterial used in soil/rock grouting techniques in different branches of civil engineering. The objective of this work is to review CS treatment methodologies and emphasize the critical factors that influence both CS delivery and the ground improving effect. Based on the conclusions drawn in previous literature, this paper refines the concept of CS concentration and curing time being the two dominant factors that determine the strengthening effect. Finally, the evidence from the elemental tests, model tests, and field tests is reviewed in order to demonstrate CS’s ability to inhibit pore water pressure and lower liquefaction risk. Silica content and chloride ion concentration are two effective indicators recommended in this paper to judge CS converge. Thereafter, four chemical and physical methods that can examine the grouting quality are summed and appraised. Then, evidence that can justify the feasibility of CS transport in loose sand layers is demonstrated, summarizing the crucial factors that determine the rate of CS delivery. This paper firstly introduces molecular structures and some physical properties of CS, which are of great importance in the practical application of CS. It possesses a great ability to restrain pore pressure generation during seismic events by using an innovative stabilization technique, with the advantages of being a cost-effective, low disturbance, and environmentally friendly method. In the booming field of nanotechnology, colloidal silica (CS) has been introduced for ground improvement and liquefaction mitigation.
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