Characterization of rice straw ash: microstructural, compositional, phase identification, and thermal analyses of...

In recent years, biomass-based power plants have been established to produce electricity while mitigating health and environmental hazards caused by the open-field burning of rice straw. During energy production, rice straw ash is generated as a byproduct, which is generally disposed of in nearby water bodies or open lands. Therefore, considering the need for its management and the limited availability of information on RSA, the current study aims to determine and compare the microstructure, chemical composition, phase identification, functional groups, thermal stability, and pozzolanic activity of raw (RRSA) and processed rice straw ash (PRSA) (using a ball milling machine) utilizing advanced characterization techniques. Furthermore, this study presents a comprehensive performance assessment of RRSA and PRSA by analyzing their incorporation into cement-based products in terms of hardened properties (compressive strength, porosity, and hydration), cost analysis, and global warming potential (GWP) to assess their practicality and effectiveness as alternative materials for construction applications. The characterization techniques revealed that PRSA exhibited enhanced attributes, including greater silica content, five times smaller particle size, higher amorphous content, and 1.7 times greater thermal stability compared to RRSA. Additionally, the Frattini test indicated that PRSA possesses nearly twice the pozzolanic reactivity of RRSA, confirming its superior chemical contribution to the cementitious matrix. Cement-based samples incorporating PRSA demonstrated around 15% and 3% higher compressive strength, and 16% and 5% lower porosity compared to those with RRSA and the control mix, respectively. While the GWP of PRSA-blended mixes remained comparable to RRSA and the control mix, the production cost was notably higher because of energy-intensive processing. Based on the aforementioned findings, PRSA demonstrates greater potential than RRSA as a sustainable and efficient supplementary cementitious material, with promising applications in the construction sector.