Influence of bottom ash and polypropylene fibers on the physico-mechanical, durability and thermal performance of foam concrete: An experimental investigation

Recently, foam concrete (FC) has been widely considered due to higher workability, lightweight, lower cost, thermal and fire resistance relatively to conventional concrete. This study intends to measure the properties of FC incorporating bottom ash (BA) as fine aggregates (FA) and polypropylene fibers (PPF). A total of 18 concrete mixes were produced with two cement contents: 300 and 400 kg/m³. In addition, three foam agent contents (40, 50, and 60 kg/m³) and three PPF contents (0, 0.5, and 1% in terms of volume) were used and considered to investigate the physical, mechanical, thermal, and durability properties of PPF-reinforced FC incorporating BA. Furthermore, the effect of elevated temperature on the properties of specimens was also examined. Results show an increase in apparent porosity, water absorption, and sorptivity of FC with the increase in foam agent content. Conversely, a reduction in thermal conductivity, porosity, and shrinkage is observed with an increase in foam agent, cement, and PPF contents, respectively. The rise in foam agent content declines the mass loss while improves both compressive and flexural strengths of FC under an elevated temperature. Scanning electron microscopic (SEM) analysis of the FC specimens after exposure to the elevated temperature shows the cracks and inter-connected pores due to the thermal stresses by decomposing calcium silicate phases. Results show that all the FC mixes incorporating BA as FA and PPF can be used as moderate-strength concrete following American Concrete Institute guidelines, leading to enhanced FC performance and sustainable construction.