Experimental Investigation on Mechanical and Durability Properties of Sustainable Fly Ash–GGBS Based Concrete

Abstract

As the interest grows in the use of sustainable building materials, there is considerable research that has been carried out to partially replace ordinary Portland cement (OPC) with supplementary cementitious materials (SCMs). The aim of this study is to examine the mechanical properties of concrete produced using fly ash and ground granulated blast furnace slag (GGBS) as partial replacement of cement (M40 grade). To design an experimental program, six mix proportions were designed, a control mix (M0) and five blended mixes (M1 – M5) with different proportions of fly ash and GGBS. The mechanical properties were tested using compressive strength, split tensile strength and flexural strength tests after 7 days and 28 days. The outcome showed that control mix had better early age strength, whereas mixes added with SCMs had slightly lower early age strength attributed to slower hydration kinetics. At 28 days, however, the blended mixes showed marked strength development with the split tensile strength over 4.0 MPa, flexural strength over 6.0 MPa and compressive strength above 41 MPa. The synergic effect of fly ash and GGBS helped in a better microstructural densification, durability potential and long term strength development. This study validates that fly ash and GGBS addition to M40 grade concrete reduces cement consumption, environmental impact and still maintains the mechanical properties same or better to that of conventional concrete. The research demonstrates the potential of SCMs to develop sustainable high performance concrete for structural applications, which is consistent with global trends on mitigation of carbon emissions and development of circular economy in the construction sector.