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.
Acknowledgments
The first author would like to express the special thanks and deep love to Mami Jane and Little Nara −June 11, 2020 Welcome- for warming and energizing his heart. Thanks to Ms. Narunchra Danintar, a master student and research assistance, for working hard on this project. The first author would also like to acknowledge the financial support of the Murata Science Foundation (MSF2020) research grant 2020. This research work was partially supported by Chiang Mai University (CMU), Thailand. The fifth author would like to acknowledge the financial support of the Thailand Research Fund under the TRF Distinguished Research Professor Grant No. DPG 6180002. The research team of the Civil Engineering Department at Chiang Mai University, Khon Kaen University, Thailand, and Brunel University London, UK, are also gratefully acknowledged for providing guidance and valuable input to this work.