The highs and lows of incorporating pozzolans into concrete and mortar: A review on strength and durability

Abstract

It has been established that the construction industry, especially with regards to the production and use of cement generates lots of toxic gases, as well as consumes large quantities of natural resources. Cement itself is an expensive constituent of concrete. In order to reduce environmental pollution, improve cost-savings in production, achieve carbon neutrality and sustainability, the focus should be directed at using alternative waste materials such as ceramic waste, waste glass, palm oil waste, and rice husk, among others. This paper presents a widescale review of the incorporation of pozzolans into concrete and mortar, highlighting the effects on its strength and durability. The review revealed that while the existing literature agrees that the incorporation of pozzolans into mortar and concrete generally improves their durability, there is an apparent contradiction in various research findings on the effect of pozzolans on their strength. The review has shown however that whether the inclusion of pozzolan will increase or decrease strength depends on a number of factors such as Portland cement replacement level, fineness of the pozzolan (particle size of the ash), the reactivity of the pozzolan, concrete/mortar age, type of pozzolan, water-cement ratio, burning temperature, the microstructure of the pozzolan (weakly or strongly amorphous).