Mechanical properties and durability of ECC incorporating LC3 and RFA in chloride environment

Durable and sustainable construction materials with high resistance to aggressive environments are essential for extending the service life of infrastructure and minimizing environmental impact. However, conventional concrete is brittle, exhibiting compromised mechanical performance, lower tensile strength, and reduced durability in chloride-rich environments, thus failing to meet critical sustainability benchmarks. This study addresses these challenges by developing high-performance engineered cementitious composites (ECC) that incorporate limestone calcined clay cement (LC 3 ) and recycled fine aggregates (RFA), promoting circular economy principles and reducing reliance on virgin materials. The aim is to enhance mechanical properties, durability, and self-healing capacity. LC 3 was used to partially replace cement at levels of 0%, 35%, 50%, and 65%, while RFA fully replaced natural silica sand. Mechanical performance was evaluated through compressive strength, tensile strength, and flexural strength test, while durability was assessed via chloride exposure behavior, chloride penetration resistance, and self-healing under saline immersion. Results demonstrated that compressive strength increased by up to 66.3%, while tensile strain capacity and tensile stress improved by 53.7% and 50%, respectively. Compared to reference specimens, the ECC exhibited a 188.7% increase in strain energy, a 186% rise in microcrack formation density, and a 64% reduction in average crack spacing. Flexural strength improved by 43%, and flexural deformation increased by 118%. Self-healing was more pronounced at higher LC 3 dosages when cracked LC 3 -RFA-ECC specimens were immersed in NaCl solution for 9 months. Resistance to chloride penetration improved by up to 59% in LC 3 -based specimens. Post-chloride exposure performance also showed significant gains, with compressive strength increasing by up to 42.9%, flexural strength by 27%, and flexural deformation by 137%, relative to reference specimens. These improvements are attributed to the synergistic interaction of LC 3 and RFA, which promote matrix densification and crack-closing mechanisms. Overall, this study presents a novel, durable, and eco-efficient ECC for real-world infrastructure in chloride-rich marine and coastal environments, offering both performance and sustainability benefits.