SULFATE AND CHLORIDE RESISTANCE OF NANOSILICA AND MICROSILICA CONTAINED SELF-CONSOLIDATING CONCRETES

Abstract

This comparison study focuses on the impacts of using nano-silica (nS) on chemical attack resistance of self-consolidating concrete (SCC) and its effectiveness in comparison to similar replacement levels of the more widely employed micro-silica (mS). Two types of cement were used to produce concrete mixes and three different percentages (3, 4.5, and 6 %) of nanosilica and microsilica were added as a replacement of cement by weight. Concrete specimens were cast and exposed to four harmful conditions including: sulfate solution, chloride solution and both of them for a period of up to 400 days. Based on the obtained results, replacement with colloidal nS proved to be significantly more effective in the chemical resistance than equivalent replacement of dry powder mS. The noticed improvements in chloride resistance and chloride penetration performance for concretes contained nS was correlated with the compressive strength results, which indicates for better pore structure characteristics. As expected, the improvement in the chemical resistance was more pronounced in concretes with cement type V.