Strength and sulphate resistance of high performance concrete containing different fineness of Palm oil fuel ash

Abstract

This research aims to study the effect of different fineness of Treated Palm oil fuel ash (T-POFA) on the strength and sulphate resistance of high-performance concrete (HPC). For this research, besides the control mix, two mixes with fineness of 45 μm and 150 μm of POFA were prepared with 20% replacement with ordinary Portland cement (OPC). For sulphate resistance, the concrete specimens were immersed in 5% sodium sulphate solution to investigate the sulfate resistance in accordance with appropriate ASTM standards. In addition to that, the higher fineness of T-POFA gives better resistance towards sulphate attack due to its pozzolanic reaction. From the tests that were carried out, the results showed that 20% of 45 μm T-POFA replacement in HPC concrete gives the lowest in compressive strength loss at 120 days compared with 150 μm replacement and control HPC concrete in sulphate attack. It is noticed that, the compressive strength of 45 μm T-POFA shows increment in compressive strength after 120 days of immersion due to the pozzolanic reactions that took place. This in turn gives extra layer of C-S-H to concrete which strengthened the bond. Therefore, the higher fineness of T-POFA gives better resistance towards sulphate attack. This result suggests that concrete design of high performance concrete (HPC) contains POFA 45 μm is better to be used as a cement replacement compared with POFA 150 μm and control concrete for sulphate resistance.