Feasibility of engineered cementitious composites implementing combined systems of post-processed bagasse ash and fly ash as SCMs

This study investigated the feasibility of using post-processed bagasse ash (PBA) in combination with class F fly ash to replace a high quantity of cement (i.e., 75% by mass) in ECC mixtures. PBA was prepared by drying, sieving, burning, and grinding raw sugarcane bagasse ash (SCBA) collected from a sugar mill. Combinations of fly ash with PBA evaluated as SCMs included: (1) 25% PBA and 75% FA; (2) 50% PBA and 50% FA; (3) 75% PBA and 25% FA; and (4) 100% FA as control. ECC materials prepared were evaluated by compressive strength test, surface resistivity test, and uniaxial tensile test. Experimental results revealed that the replacement of fly ash with PBA produces a minor decrease in the compressive strength (i.e., up to 13.3% compared to control) while increasing the surface resistivity (i.e., up to 81.8% compared to control). Furthermore, a progressive decrease in tensile strain capacity was observed with the increase in PBA content (i.e., up to 68.5% compared to control). However, ECCs implementing PBA exhibited higher first-cracking and tensile strength compared to the control (i.e., up to 28.2 and 27.0% and, respectively). It was hypothesized that, compared to class F fly ash, PBA is less effective at reducing the fiber/matrix chemical bond and the matrix fracture toughness, thus explaining the increase in first-cracking and tensile strength as well as the decrease in tensile ductility observed when partially replacing fly ash with PBA. Nevertheless, using combinations of PBA and class F fly ash as SCMs in the manufacture of ECC materials can be feasible as the replacement of 25% of fly ash with PBA minorly affected the compressive strength and tensile ductility of the composites while increasing the tensile strength and surface resistivity