Effect of treated and untreated rice husk ash, palm oil fuel ash, and sugarcane bagasse ash on the mechanical, durability, and microstructure characteristics of blended concrete - A comprehensive review

Cement production is a high-energy-intensive process that generates large amounts of carbon dioxide (CO2) and other hazardous pollutants. On the contrary, considerable amounts of rice husk ash (RHA), palm oil fuel ash (POFA), and sugarcane bagasse ash (SBA) are dumped in open landfills, resulting in water and land pollution. The use of RHA, POFA, and SBA as cementitious supplementary materials to develop sustainable concrete presents a potential solution to address these environmental challenges. This paper comprehensively reviews the hydration mechanism as well as the physical, chemical, morphological, and mineralogical properties of RHA, POFA, and SBA. Furthermore, it critically compares the impact of thermal and non-thermal treatment of RHA, POFA, and SBA on the mechanical and durability properties of blended concrete, including normalised compressive strength, normalised splitting tensile strength, normalised flexural strength, normalised modulus of elasticity, water absorption, ultrasonic pulse velocity, acid resistance, and sulphate resistance. Moreover, this paper demonstrates SEM (Scanning electron microscope) images with EDS (Energy dispersive spectroscopy) and XRD (X-Ray diffraction) patterns of both the treated and untreated RHA, POFA, and SBA blended concrete. The study indicates that the treated RHA, POFA, and SBA significantly enhance the mechanical and durability properties of blended concrete. SEM images and XRD analysis confirm that the thermal treatment of RHA, POFA, and SBA compact the concrete matrix by generating secondary C-S-H and the filler effect of these materials. This review also offers valuable direction for future studies to explore the potential of these materials in the construction industry.