Influence of limestone powder on mechanical, physical and self-healing behavior of Engineered Cementitious Composites

Environmental considerations have led to a global trend of using blended cements instead of ordinary Portland cement; cements containing limestone powder (LP) have recently entered the market. This research focuses on the effect of replacing LP content with cementitious material on the performance of Engineered Cementitious Composite (ECC) containing high-volume fly ash (FA). For this purpose, ECC mixtures were created in which cement and FA were partially replaced by 5%, 10% and 20% of LP and ECC mixture without LP (as control). The samples were precracked at the age of 28 days and left under continuous water curing (CW) for recovery of their properties. Compressive strength, modulus of rupture (MOR), mid-span beam deformation capacity, rapid chloride penetration testing (RCPT) and resistivity testing were used to assess the mechanical, physical and self-healing capability of ECC mixtures. Experimental results show that all mixtures exhibited self-healing with slight differences. Microstructure was also assessed using SEM-EDS and XRD analysis. The microstructural analysis of healed cracks in LP-incorporated ECC mixtures showed the presence of calcite, portlandite and C-S-H gels as well as monocarboaluminate, which confirmed a possible reaction between FA and LP. Due to self-healing, the recovery in mechanical and durability performance of the mixtures proposed in this research is anticipated to positively affect life cycle costs and lead to increased civil infrastructure sustainability.