Recent developments in utilization of nano silica in self-compacting concrete: A review

Self-compacting concrete (SCC) is a type of flowable, high-strength and high-performance concrete in the construction field, which can flow and compact under its own weight. The damage of concrete is often caused by internal microstructural defects. Nano silica (NS) has excellent pozzolanic properties, and with an appropriate content of NS as auxiliary cementing material, it can promote the generation of C-S-H gels in addition to serve as internal filler, thus improves the micro-scale defects in concrete. This paper extracts data from studies published over the last decade which focus on the application of NS in SCC and discusses the similarities and differences between the studies. Ultimately, a systematic review of the physical and chemical characteristics of NS, and the effect of NS on the workability, mechanical and durability properties of SCC is presented. Based on the review, the most common NS content is 0%-6%, where the negative effect of 0%-6% NS on the workability of SCC can be controlled by increasing the dosage of superplasticizer. The NS content of 2%-3% is optimum for improving the mechanical strength and the ability of SCC to resist water permeability, corrosion, acid and sulfate attacks, elevated temperature as well as shrinkage.