Synergetic effect of sugarcane bagasse ash incorporated in slag-based alkali-activated recycled aggregate concrete: Role of activator to precursor ratio on the corrosion behavior

The production of Portland cement consumes substantial energy and natural resources, resulting in significant CO 2 emissions. This study develops recycled aggregate alkali-activated concrete (ARC) using sugarcane bagasse ash (SBA) and granulated blast furnace slag (GGBS) to enhance sustainability. Given the susceptibility of reinforced concretes to chloride-induced corrosion, particularly in marine environments, evaluating the durability of ARC is essential before widespread application. This study examines how the activator-to-precursor (A/P) ratio governs the structural and corrosion performance of SBA-GGBS-based ARC. Mixes with A/P ratios ranging from 0.3 to 0.8 were developed, and their corrosion behavior was monitored over 365 days using electrochemical techniques, including alkalinity, electrical resistivity, half-cell potential, and Tafel extrapolation to determine corrosion rates. Corresponding TGA–DSC and XRD analyses were conducted to support these findings. All SBA-GGBS-based ARCs maintained high alkalinity, exhibiting pH values greater than 10.5, indicating a low risk of depassivation across all A/P ratios. Mixes with A/P lower than 0.5 consistently exhibited higher resistivity, lower corrosion likelihood, and earlier stabilization of corrosion rates. Mixes with A/P < 0.5 exhibited the most stable electrochemical conditions, representing the threshold for good-quality concrete with low chloride penetration and reduced corrosion rates. Lower A/P ratios form a denser C–(A)–S–H matrix that restricts ion transport and improves corrosion performance. These results highlight the A/P ratio as a key factor in SBA-GGBS-based ARC performance. Understanding and optimizing this parameter is essential for ensuring reliable performance under site-specific conditions and varying project requirements. • This research examines the impact of A/P on the corrosion performance of SBA-based ARC. • SBA-based ARCs exhibit minimal risk of reinforcement corrosion as they maintain pH > 10.5. • SBA-based ARC mixes exhibited negligible corrosion rates after 365 days. • TGA-DSC results reveal the formation of dense cross-linked C–(A)–S–H gel, restricting the transport of aggressive ions responsible for corrosion.