Effects of micro- and nano-silica on the mechanical performance and fracture behavior of self-compacting concrete

This article presents an experimental investigation aimed at determining the fracture properties of self-compacting concrete (SCC) that contains micro-silica (MS) and nano-silica (NS). Portland cement was replaced with 0% and 10% MS, as well as 0%, 1%, 3%, and 5% NS, in various mixtures. The water-to-cement ratios (W/C) used in this study were 0.35 and 0.45. For all mixtures, the fracture parameters were assessed using both the work of fracture method (WFM) and the size effect method (SEM). The study involved conducting three-point bending tests on 240 notched beams with a total of 16 different mix designs. The results indicated that incorporating MS and NS into SCC mixtures increased the viscosity while reducing the flowability of the fresh concrete. The incorporation of 10% MS and 3% NS at W/C ratios of 0.35 and 0.45 yielded the maximum values of the total fracture energy (GF) and the initial fracture energy (Gf). In comparison to the control mix, the GF and Gf values for the sample containing 10% MS and 3% NS increased by 16.46% and 22.94%, respectively, at the W/C ratio of 0.35.