Characteristics of palm oil fuel ash concrete admixed with precipitated silica and silica fume

This study investigates the characteristics of blended Palm Oil Fuel Ash (POFA) concrete admixed with silica fume (SF) and precipitated silica (SP) as a cement replacement material for Portland Composite Cement (PCC). The study aims to evaluate the potential of precipitated silica extracted from POFA as an alternative to commercial silica fume in enhancing the properties of palm oil fuel ash concrete. Four different mixes were studied, including a control mix with PCC and three mixes with varying amounts of POFA, SF, and SP. The study analyzed the fresh properties, compressive strength, strength activity index, tensile strength, and microstructure of the concrete. The results showed that the addition of SF and SP increased the compressive strength of the POFA concrete by 23.34% and 38.11% respectively at 28 days. The strength activity index was also higher in the mixes with silica, indicating a higher pozzolanic activity at early ages. The tensile strength and porosity of the concrete were also improved with the addition of silica. The SEM and FTIR analysis confirmed that the addition of silica, especially precipitated silica, improved the microstructure of the concrete. The study concludes that the precipitated silica from POFA has the potential to be used as a cement replacement or additive in POFA concrete manufacturing in Asian countries where POFA is abundantly available.