Mechanical properties, chloride resistance and microstructure of Portland fly ash cement concrete containing high volume bagasse ash

Abstract

In this paper, the mechanical properties, chloride resistance and microstructure of Portland fly ash cement concrete containing high volume bagasse ash (BA) were studied. Both binary and tertiary blended cements were studied and compared. For binary blend, ordinary Portland cement (OPC) was replaced with BA at 50%, 60%, and 70% by binder weight. In the ternary blend, OPC was replaced with 50% and 60% BA and 10% and 20% FA by weight of binder. A water to binder ratio of 0.40 was used and the workability of fresh concrete was maintained by adding a superplasticizer. The compressive strength, splitting tensile, chloride resistance, corrosion resistance of reinforced steel, porosity and scanning electron microscopy of concrete were investigated. The results showed that for the binary system, the incorporation of high volume BA increased the amount of superplasticzer to maintain the workability and the compressive strengths at 28 days was lower than that of the control concrete. However, the resistance to chloride penetration of high volume BA concrete increased with increasing BA. The critical pore size of high volume BA concrete was lower than that of control concrete. the incorporation of high volumes BA reduced the pore size of the matrix by reducing the coarser pores to finer medium capillary pores. In addition, the high volume BA concretes showed significant increase in the 90-day compressive strength from the pozzolanic reaction. For the ternary blend, the incorporation of FA into the system helped the workability of the mixes. The results also indicated that the ternary blend mixture showed that the mix with 50%BA and 20%FA was the best considering the strength, durability and cost. The use of both BA and FA resulted in concretes with good resistance to chloride permeability, which led to a beneficial improvement of corrosion resistance. The results confirmed that the use of high volume BA-FA concrete as an eco-friendly construction material resulted in improved durability and cost saving.