Briefing: Improving erosion resistance of sand using nano-silica additive

Abstract

This briefing paper examines the improvement in the hydraulic erosion resistance of medium silica sand achieved using 1–4% nano-silica (NS) additive. The erodibility of the different soil blends (prepared by mixing NS solutions prepared at required concentrations with the dry test sand) was investigated at bench scale by testing compacted treated sand specimens using the erosion-function apparatus. The NS addition produced a viscous gel property for the soil mixtures, allowing the mobilisation of an effective cohesion (surface bond strength). A 1·5% NS addition was identified as the optimum amount in terms of the greatest erosion resistance for the particular sand investigated; that is, a 92% reduction in the erodibility coefficient value and an approximately six-fold increase in the critical shear stress value were achieved relative to the untreated sand. Further, these improvements in the erosion-resistance properties of the compacted sand–NS mixtures were achieved within a significantly shorter time period (i.e. 1 d specimen curing period adopted in the current investigation) when compared with that typically required for traditional cement and lime additives.