Development of novel self-healing strain-hardening cementitious composites (SH2CC) for dynamic cyclic loading conditions using mineral and polymer admixtures

Abstract

Dynamic cyclic loading commonly encountered in engineering practice can pose great threat to the integrity and durability of concrete infrastructures. Ductile materials with enhanced self-healing performance could provide a promising solution under such conditions. This study proposes and investigates, for the first time, as self-healing SHCC (SH2CC) for dynamic reversed-cyclic (DRC) applications through incorporating a mineral substitute (MS) comprising of reactive MgO and quicklime and triethanolamine (TEA) additive in a high-volume-fly-ash matrix. Different DRC preloads were considered. Results indicated that applying 5% MS combined with 1.5% TEA additive showed optimal crack width control below 12 μm under up to 5 cycles of DRC preloading and the highest potential for mechanical strengthening of modulus of rupture, first cracking strength and flexural stiffness reaching up to 160%, 137% and 210% respectively after healing. Moreover the highest crack sealing efficiency was observed up to 88% under 14d water immersion. Microstructural analysis revealed that MS produced additional hydrates and promoted more carbonates to form in cracks during healing, while TEA effectively paused hydration under air curing but resumed the process upon water contact for massively enhancing crack healing (especially mechanical strengthening). Combining MS and TEA in SH2CC produced complementary healing products both in cracks and fibre-matrix interfaces indicating better filling and bridging of the cracks and demonstrating great potential for enhancing healing performance under aggressive loading conditions.