Properties of Engineered Cementitious Composites Using Combined Systems of Fly Ash and Post-Processed Bagasse Ash as Supplementary Cementitious Materials

Abstract

This study assessed the viability of utilizing post-processed bagasse ash (PBA) along with Class F fly ash (FA) to partially replace cement in engineered cementitious composites (ECCs). Field-collected sugarcane bagasse ash was processed by sieving, burning, and grinding to produce PBA. Cement replacement with supplementary cementitious materials (SCMs) was kept constant at 60% (by mass) in all composites. However, the composition of the SCMs was varied as follows: (1) 100%FA as control; (2) 75%FA/25%PBA; (3) 50%FA/50%PBA; (4) 25%FA/75%PBA; and (5) 100%PBA. Fresh and hardened properties of the composites were evaluated through a flow table, uniaxial tensile tests, surface resistivity, and compressive strength. Furthermore, single-crack tensile tests were conducted to evaluate fiber-bridging properties, and fracture toughness tests were conducted to determine fracture toughness. Results showed that the incorporation of PBA decreased workability. Furthermore, using PBA produced a negligible impact on the compressive strength, yet significant improvements in surface resistivity. Whereas the tensile strain capacity of the composites decreased for PBA contents greater than 25%, the tensile strength was not significantly affected. The decrease in ductility was mainly attributed to the decrease in pseudo-strain-hardening performance indexes. Overall, results suggest that producing ECCs using combined systems of FA and PBA as partial cement replacement is feasible. Yet, achieving high ductility of the composites is challenging when utilizing high content of PBA (i.e., more than 25% of FA replaced with PBA by mass).