Effect of Fly Ash, GGBS, and Metakaolin on Mechanical and Durability Properties of Self-Compacting Concrete Made with 100% Coarse Recycled Aggregate

Abstract

In developing country such as India, due to the significant boom in the infrastructure development the virgin aggregates (VAs) resources are diminishing at a high pace and thus creating an ecological imbalance. In contrast, an immense quantity of recycled aggregates (RAs) is generated from construction and demolition waste. Thus, in view of sustainability, utilization of RA can be a great source of aggregate in the development of structural concrete. This paper outlines the development of self-compacting concrete (SCC) with full replacement of coarse VAs with coarse RAs. In addition, to make the SCC more sustainable, utilization of supplementary cementing materials such as coal fly ash (CFA), ground granulated blast furnace slag (GGBS), and metakaolin (MK) were used as cement replacement materials. Finally, the mechanical and durability performance of SCCs were examined to see whether they could be adopted for structural applications with greater confidence. A total of nine SCC mixes were designed containing GGBS, CFA, and MK content as cement replacement (by weight) with full replacement of VAs with RAs. Fresh performance of SCC mixes was scrutinized by slump flow, T500, V-funnel, and L-box test. Furthermore, compressive strength test, split tensile test, flexural test, and E-modulus test were performed to study the mechanical characteristics. Durability performance was examined by conducting water permeability, sorptivity, rapid chloride penetration test, surface resistivity, pH, and carbonation tests. The experimental results concluded that 15% replacement of cement with MK exhibited an excellent mechanical as well as durability performance of self-compacting recycled aggregate concrete with a ceiling strength of 75 MPa. The use of GGBS also yielded excellent durability performance. In contrast, the use of CFA exhibits moderate mechanical and durability performance. It can be inferred from the outcomes of this study that it is possible to develop high-performance SCC using 100% RA, by employing mineral admixtures such as CFA, GGBS, and MK.