Behavior of self-compacting concrete by the addition of recycled aggregates and nano-silica

Abstract

The construction industry is growing rapidly all over the world and busy in inventing the new construction materials. The existing construction materials which are used for constructions from past decades were accumulating on the land as a waste, due to lack of reutilizing the used materials. In this experimental work, efforts were made to re-utilize the recycled aggregates which are also called demolition waste aggregates. The current study is divided into two stages. The first stage of work examines the influence of recycled aggregates on the characteristics of self-compacting concrete (SCC). The second stage includes the substitution of cement by nano silica and replacement of normal aggregates by recycled aggregates (RA) in the SCC mix. In this study, natural aggregates are replaced by 10%, 20%, 35% and 50% with recycled aggregates by the weight of total aggregates. Nano silica (NS) is used in this study, which replaces the 0.5% and 1% by weight of cement for each partial replacement level of recycled aggregates. The workability tests were performed on prepared SCC mix. The workability properties were satisfying the requirements of SCC. The compressive, split tensile and flexural strength tests were conducted on hardened concrete. The microstructural configuration of SCC containing with and without RA & NS mixtures were examined using a scanning electronic microscope (SEM). The RCPT test was conducted to understand the durability of the SCC. The outcomes of mechanical properties were optimum at 35% replacement of RA in first stage of work. Similarly, mechanical properties were optimum at 1% of NS and 35% of RA in second stage of work. The SEM analysis reveals the micro structure of mixes, the nano silica replaced concrete mix exhibit the lesser voids compared to RA replaced concrete. It results shows that voids were filled with nano particles and enhances the performance of SCC mix.