Effect of local metakaolin developed from natural material soorh and coal bottom ash on fresh, hardened properties and embodied carbon of self-compacting concrete

The carbon dioxide emissions from Portland cement production have increased significantly, and Portland cement is the main binder used in self-compacting concrete, so there is an urgent need to find environmentally friendly materials as alternative resources. In most developing countries, the availability of huge amounts of agricultural waste has paved the way for studying how these materials can be processed into self-compacting concrete as binders and aggregate compositions. Therefore, this experimental program was carried out to study the properties of self-compacting concrete (SCC) made with local metakaolin and coal bottom ash separately and combined. Total 25 mixes were prepared with four mixes as 5, 10, 15, and 20% replacement of cement with metakaolin; four mixes as 10, 20, 30, and 40% of coal bottom ash as partial replacement of fine aggregates separately; and 16 mixes prepared combined with metakaolin and coal bottom ash. The fresh properties were explored by slump flow, T₅₀ flow, V-funnel, L-box, and J-ring sieve segregation test. Moreover, the hardened properties of concrete were performed for compressive, splitting tensile and flexural strength and permeability of SCC mixtures. Fresh concrete test results show that even if no viscosity modifier is required, satisfactory fresh concrete properties of SCC can be obtained by replacing the fine aggregate with coal bottom ash content. At 15% replacement of cement with local metakaolin is optimum and gave better results as compared to control SCC. At 30% replacement of fine aggregate is optimum and gave better results as compared to control SCC. In the combined mix, 10% replacement of cement with metakaolin combined with 30% replacement of fine aggregate with coal bottom ash is optimum and gave better results as compared to control SCC.