Ground palm oil fuel ash and calcined eggshell powder as SiO2–CaO based accelerator in green concrete

Abstract

Some applications in the construction industry such as precast concrete demand for early strength development. This is normally achieved using accelerator, but most accelerators in the market contain chemicals that adversely affect the environment. This study proposes the incorporation of ground palm oil fuel ash (GPOFA) and eggshell powder (ESP) derived from agriculture and aviculture wastes as bio-accelerator. GPOFA contains high level of silicon dioxide (SiO2) while ESP has high calcium oxide (CaO) content that are responsible for early and later strength development in concrete, respectively. The engineering, chemical and mineral properties of the resultant green concrete were evaluated and discussed. The GPOFA-ESP accelerator had enhanced the mechanical and durability of the concrete when compared to a normal concrete mix. Three types of ESP had been prepared and blended with GPOFA, namely the uncarbonized eggshell powder (UC-ESP), carbonized eggshell powder (C-ESP) and decarbonized eggshell powder (DC-ESP). The combination of 15% GPOFA and 5% DC-ESP resulted in a concrete with the highest average compressive strength, flexural strength and splitting tensile strength consistently over a 90-day curing period. The concrete also had the smoothest surface, highest resistance to chloride and sulphate attack. Thus, this study strongly proposes further research into this GPOFA-ESP combination as concrete accelerator to contribute towards a more sustainable future.