Effect of microwave-assisted curing process on strength development and curing duration of cellular lightweight geopolymer mortar

Abstract

The heat curing process using an electric oven has been generally applied for curing geopolymer material as it accelerates strength development. However, a microwave curing process is an alternative approach to obtain a shorter heat curing process. This paper focuses on the strength development and required curing duration of a cellular lightweight geopolymer mortar using a microwave-assisted curing process. Other curing approaches, namely (i) room curing process, (ii) typical oven curing process, and (iii) microwave curing process, were also comparatively examined. Bottom ash was used as light-fine aggregate to replace sand by 0%, 25%, 50%, 75%, and 100%. The results revealed that replacing 25% of the sand with bottom ash provided the optimal strength and low density for all mixtures. A 28-day age strength of 12.27 MPa was achieved by the microwave-assisted curing process, while a strength of 5.77 MPa was achieved by the typical oven curing process. The microwave-assisted curing process could significantly improve the early strength development and reduce both the overall curing period and energy consumption by around 75% compared to a typical oven curing process. This approach could be applied as an alternative geopolymer synthesis for the development of environmental-friendly construction material for lightweight applications.