Exploring the potential of sugarcane bagasse ash as a sustainable supplementary cementitious material: Experimental investigation and statistical analysis

Exploring nonconventional cementitious materials is vital for enhancing material performance, reducing construction industry's environmental footprint, and promoting sustainable resource management. This study investigated the potential of minimally processed sugarcane bagasse ash (SCBA) as a supplementary cementitious material in mortar mixes, examining its effects on compressive strength, ultrasonic pulse velocity, density, water absorption, and microstructure. Notably, the SCBA used in this study was processed with minimal energy input, involving only sun drying, coarse sieving through a 150-μm mesh, and gentle oven drying to remove residual moisture. In this view, seven cementitious mixes were prepared, comprising a control mix and six mixes with SCBA replacement levels ranging from 5 % to 30 % by weight of binder (Cement + SCBA). Initially, the 7-day compressive strength decreased with increasing SCBA replacement, whereas 28-day strength increased for mixes containing 5–15 wt% SCBA, with a maximum 12.67 % increase at 5 wt% replacement, and all mixes up to 15 wt% SCBA met ASTM C270 specifications. Up to 5 wt% SCBA substitution enhanced both ultrasonic pulse velocity (UPV) and density, but further additions led to decreased UPV and density values due to the formation of a porous microstructure resulting from increased SCBA content. However, despite this decrease, mortars containing up to 15 wt% SCBA achieved UPV values surpassing the literature-defined thresholds for good (3500 m/s) and excellent (3800 m/s) quality cement mortar at 28 days, indicating yet a well-packed microstructure. The incorporation of upto 15 wt% SCBA resulted in reduced water absorption at 28 days, meeting the requirements of ASTM C62. A quadratic regression model was employed to investigate the relationship between SCBA content and mortar properties, including compressive strength, ultrasonic pulse velocity, density, and water absorption. The analysis revealed a statistically significant fit (p < 0.05) with a high coefficient of determination (R2 > 0.90), indicating a strong relationship between SCBA content and mortar properties. Microstructural evaluation confirmed beneficial effects of SCBA incorporation on mortar morphology, within moderate dosage ranges (up to 15–20 wt% SCBA). The study highlights the potential of using energy-efficient SCBA as a sustainable supplementary cementitious material to improve mortar mix performance and contribute to the development of environmentally friendly cementitious materials.