Effect of elevated temperatures on strength and microstructural characteristics of foam concrete containing palm oil fuel ash as sand replacement

Abstract

Reducing the environmental impact of the construction industry has gained researchers’ attention in recent years. Using industrial by-products in concrete production and enhancing the thermal performance of concrete remarkably reduce carbon dioxide (CO2) emission during the construction and operation phases of the building. Fire is known to severely affect the different properties of concrete. Previous studies have shown that foam concrete has superior thermal insulation and better fire resistance than conventional concrete. Therefore, this research aims to study the effect of palm oil fuel ash (POFA) as a sand replacement on the performance of foam concrete exposed to high temperatures. Foam concrete with a density of 1500 kg/m3 was prepared by replacing sand with 0%, 10%, 20%, 30% and 40% POFA. The specimens were exposed to a series of high temperatures (200 ℃, 400 ℃, 600 ℃ and 800 ℃) for an hour. The fire resistance of foam concrete was measured in terms of density loss, residual strength and modulus of elasticity. The role of POFA was also investigated through microstructure analysis using scanning electron microscopy, X-ray diffraction, thermogravimetric analysis (TGA) and derivative thermogravimetric analysis. Results showed that density reduction and microstructure deterioration began at 200 °C, whereas compressive strength, modulus of elastic, and crystalline structure deterioration began at 400 °C. The use of POFA improved foam concrete residual strength, increased residual modulus of elasticity and increased weight loss; this impact was more pronounced at 800 ℃. POFA was also found to improve foam concrete microstructure and showed an insignificant effect on its crystallin diffractogram at all temperatures. Overall, this study confirms that the use of POFA as a sand replacement can enhance the fire resistance of the foam concrete.