Mix design and performance of low-carbon alkali-activated slag/bagasse ash cementitious materials

The utilization of sugarcane bagasse ash (SCBA) in alkali-activated materials (AAMs) is currently limited due to its subpar mechanical properties and the absence of a mix design approach. This study aimed to develop a high-strength, cost-effective, and low-carbon alkali-activated slag/bagasse ash (AASL/BA) composites through multi-objective optimization (MOO) models. The results showed that increasing SCBA content reduced the compressive strength of AASL/BA, particularly beyond 50%. Moreover, elevating the SiO2/Na2O molar ratio to 1, along with a Na2O content of 6%, notably increased the compressive strength by 276% and the proportion of C-(A)-S-H to 31%. Furthermore, a comprehensive MOO model, considering SCBA content, SiO2/Na2O molar ratio, Na2O dosage, cost index (CI) and environmental index (EI), was established. Optimal parameters were identified as SCBA content below 50%, SiO2/Na2O molar ratio ranging from 0.5 to 1.0, and Na2O dosage between 4% and 6% to achieve produce high-strength, cost-effective, and environmentally friendly AASL/BA. This work lays a solid groundwork for the sustainable design of AASL/BA materials.