Review on Nano-Silica and Nano-Clay in Cementitious Composites

The integration of nanomaterials in cementitious composites has emerged as a promising approach to enhance mechanical strength, durability, and microstructural refinement. This review examines the effects of nano-silica (NS) and nano-clay (NC) on the properties of cement-based materials. Studies have shown that NS significantly improves compressive strength, reduces permeability, and accelerates hydration due to its pozzolanic activity and filler effect. The optimal replacement levels of NS range from 1% to 5%, with higher percentages showing diminishing returns. Similarly, NC has demonstrated its ability to enhance flexural strength and fracture toughness, with an optimum dosage of around 1% by weight. The synergistic effect of NS and NC further enhances performance by improving microstructure and reducing porosity. However, excessive nano-material content can negatively impact workability and durability. This review also highlights the role of particle size, dispersion, and interaction with cement hydration products in optimizing performance. The findings suggest that controlled use of nanomaterials can lead to the development of high-performance and sustainable cementitious composites.