Mechanical and autogenous healing properties of high-strength and ultra-ductility engineered geopolymer composites reinforced by PE-PVA hybrid fibers

This study introduces high-strength and ultra-ductility engineered geopolymer composites (HSUD-EGCs). Four HSUD-EGC mixtures were designed and prepared using slag blended fly ash binders and hybridized fibers composed of polyethylene (PE) and polyvinyl alcohol (PVA). Reinforced by 1.5% PE-PVA fiber volume fraction, a mixture using a slag-to-fly ash weight ratio of 5.5:4 showed compressive strength of up to 87 MPa and tensile strain capacity of up to 10.5%, whereas a mixture using a slag-to-fly ash weight ratio of 3:6.5 achieved compressive strength of 50 MPa and tensile strain capacity of up to 12%. In addition, HSUD-EGCs showed higher cost effectiveness compared to the previous high-performance ECCs and EGCs. HSUD-EGCs had relatively limited autogenous healing potential in terms of crack sealing and stiffness recovery, but high tensile performance in the post-healing re-loading stage. Through chemical analysis, it was found the major healing material of HSUD-EGCs is C-(N)-A-S-H gel.