Influence of silica fume on the workability and hydration process of ultra-high performance concrete

Abstract

The present article reviews the influence of silica fume on the workability and hydration process of ultra-high performance concrete (UHPC). Silica fume, also known as microsilica (MS) or condensed silica fume, is a by-product of the production of silicon metal or ferrosilicon alloys. Silica fume is one of the most effective pozzolanic additives which could be used for ultrahighperformance and other types of concrete. According to the literature review, it is not entirely clear which amount of silica fume is optimal, how silica fume affects the hydration process; although the literature is rich in reporting on silica fume, however, most of the scientists are concentrated on workability and compressive strength. The purpose of this research is to extend knowledge on the workability and hydration process of ultra-high performance concrete affected by different amounts of silica fume. For investigation, slump, viscosity, qualitative and quantitative XRD analysis and compression strength tests were applied. The hydration time was reduces by 4.5 hours, and the compressive strength was increased by 30 % (from 95 MPa up to 127 MPa).