Formation of silica grout curtains and containments in mineralized groundwater

Abstract

An experimental investigation was conducted to evaluate the performance (as reflected by changes in permeability) of grouted soil specimens subjected to waters of various chemistry (mineralized groundwater) under a gradient of approximately 18. The specimens were composed of pure silica sand and clayey silty sand injected with one of two types of sodium silicate grout (sodium silicate + ethyl acetate-formamide, and sodium silicate + calcium chloride). The grouted specimens were tested in an environment that simulated different waters (distilled, freshwater, and saltwater). This work investigated the effects of curing time, environment, grout contents, and groundwater quality on the behaviour of silicate-grouted specimens, and analysed curtain formation mechanism. The test results showed that sodium silicate with ethyl acetate-formamide (SA) exhibited an increase in permeability when subjected to both freshwater and saltwater. Sodium silicate with calcium chloride (SC), however, maintained permeability properties when subjected to both freshwater and saltwater. The SC grouted specimens are less vulnerable to the action of groundwater than specimens grouted with SA. Furthermore, an empirical correlation relating the permeability of ungrouted and grouted specimens under different conditions was suggested. The correlation includes new defined parameters such as curing effect factor (α) and curtain vulnerability factor (κ).