Impact of nano silica on the cementitious systems of built environment

Abstract

In today’s scenario, most of the construction materials are man-made and are naturally sourced but have limitations, especially with regard to their impact on environment. Further, the conventional materials and technologies for construction are unsustainable and less durable with fast depletion of natural resources, pollution of environment and heavy economic cost. Silica Fumes or its more finer counterpart Nano silica, made from waste materials have excellent pozzolanic, pore filling and nucleating properties and proposes to be the most promising sustainable nanomaterial aiming the ultimate solution in built environmental applications.Work presented by many authors reveal that the Silica Fumes improve the performance of cement composites and concretes through micro-level contributions but Nano silica additions have brought in further improvements. This paper reports the effect of adding colloidal Nano Silica (NS) of 5–40 nm dia. sized particles & adding them to cement: sand ratio of 1:3 with a water-cement ratio of 0.4. Due to the continued hydration mechanism of cement particles, mechanical strength results of the cementitious composites were taken at all terms up to longer term of 365 Days. The optimized quantity of NS as found in cement composites is then added to fly ash-based cement composites for compressive strength testing at both shorter, standard & longer terms following Indian standard protocols. This paper aims to investigate and analyse the mechanical performance for both blended & ordinary cement and the corresponding microstructures of Nano silica additions in ordinary cement composites. Results reveal that the non-standard mortar strength and its rapid strength gaining are particularly in favour for fly ash PPC blended cement with Nano Silica additions.