A Concrete Mixture Design of Foam Concrete Blocks with Rice Straw Ash as partial replacement for Fly Ash

Rice straw is an agricultural source converted to rice straw ash through combustion. It has pozzolanic properties suitable for concrete production. Foam concrete is a lightweight alternative to traditional concrete blocks. It integrates fly ash, a byproduct of a coal combustion. Nevertheless, concerns about fly ash's natural effects, including its adverse effects and accessibility, prompted research of alternative materials. The study focused on assessing the viability of rice staw ash as a sustainable substitute for fly ash in the production of foam concrete. Evaluation of the rice straw ash (RSA) as a feasible substitute material in foam concrete blocks (FCB) lead the researchers to develop four trial mixture designs: TM1 (0% RSA), TM2 (5% RSA), TM3 (10% RSA), and TM4 (15% RSA). Tests for compressive strength, water absorption, and dry density are performed. On the 7th, 14th, and 28th day of curing of the trial mixes, the subsequent percentages of water absorbed ranged from 10.0% to 12.96%,8.47% to 11.32%, and 6.90% to 9.80%. Likewise, the dry density changes, falling between 1090.91 and 1224.49 kg/m3, 1039.11 and 1180 kg/m3, and 1148.63 kg/m3 for the 7th, 14th, and 28th day respectively. All trial mixtures exceeded the minimum compressive strength of 500 psi, with the highest recorded at 960 psi for TM3 with 10% RSA replacement. The result shows that RSA can be substituted for FA in producing foam concrete with an optimal replacement of 10%. These findings offer valuable insights for materials engineering and construction applications, demonstrating the potential of RSA-based mixtures in various industries.