Achieving ultra-ductility exceeding 13 % and cost efficiency with rubberized alkali-activated slag-based cement-free composites

This study introduces novel ultra-ductile rubberized alkali-activated slag composites (UD-RSCs) reinforced by normal polyethylene (NPE) and selvage PE-based (SPE) fibers. Five mixtures with different sand-to-binder (s/b) and water-to-binder (w/b) ratios, as well as fiber reinforcements were designed. Then density, compressive strength, and tensile properties of UD-RSCs were measured. Mineralogy analysis was also performed to determine typical morphologies and chemical compositions of UD-RSCs. The PE fiber-reinforced UD-RSC with a sand-to-binder ratio of 0.8 showed a tensile strain capacity of up to 15.6%, higher than the minimum extensibility of rebar. SPE fiber-reinforced UD-RSC also showed a tensile strain capacity of 13.4%. Based on a comprehensive comparison, SPE-UD-RSC exhibited improved sustainability while maintaining high mechanical performance compared to PE-UD-RSCs and other ductile composites reinforced by recycled fibers. Through mineralogy analyses, robust fiber bridging behavior was elucidated and C-A-S-H gels were confirmed as the dominant hydration product of UD-RSCs. • Mechanical properties of UD-RSCs were investigated. • Silica sand increased tensile ductility of UD-RSCs. • Selvage fiber was effective as reinforcing fiber of UD-RSC. • UD-RSCs showed superior tensile ductility up to 15.6% and cost efficiency. • Typical morphologies and chemical compositions of UD-RSCs were clarified.