Effect of alkaline activator ratio on the compressive strength response of POFA-EACC mortar subjected to elevated temperature

ABSTRACT

The paper reports the outcome of the research work on mechanical and microstructural changes to palm oil fuel ash engineered alkali-activated cementitious composite (POFA-EACC) mortar exposed to different levels elevated temperatures (300–900°C) for 2 h. POFA-EACC mortar utilised in the study was prepared from POFA activated with liquid sodium silicate and sodium hydroxide and reinforcement was provided by 2% volume fraction of polyvinyl alcohol fibres. The changes in the POFA-EACC mortar microstructure were investigated by means of SEM/EDS, XRD and FTIR. After exposure, the compressive strength of mortar specimens exposed to 300°C and 900°C temperatures for all alkali-activated ratios reduced while specimens exposed to 600°C temperature recorded improved strength for all AA ratios. The increase in strength of the specimens exposed to 600°C is due to the microstructural strengthening aided by post-heating solidification of the molten phase of the POFA-EACC mortar. The highly manifested changes in the phase composition were revealed in the POFA-EACC morphology and residual compressive strength after exposure.

KEYWORDS:

• Palm oil fuel ash (POFA)
• alkali-activated mortar
• compressive strength
• elevated
• temperature

Acknowledgments

The authors gratefully acknowledge the Universiti Sains Malaysia for providing the needed support through the Research University (1001/PAWAM/814191) Grant Scheme for undertaking the research work. In addition, the support provided by the Center for Engineering Research (CER) of the Research Institute at King Fahd University of Petroleum and Minerals, Dhahran, Saudi Arabia is especially acknowledged. Special thanks are also due to United Palm Oil Industries, Penang, Malaysia for providing the palm oil fuel ash and Muhammad Halava for providing the PVA Fibres.

Disclosure statement

No potential conflict of interest was reported by the authors.