Marine-applicable high-performance LC3-ECC: synergistic enhancement of microstructural characteristics, mechanical properties and environmental benefits

This pioneering study introduces an innovative engineered cementitious composite (ECC) incorporating limestone calcined clay cement (LC 3 ), sea sand (SS), and seawater (SW) for marine infrastructure. LC 3 was used to partially replace cement at 0 %, 35 %, 50 %, and 65 %, while SS and SW fully replaced traditional silica sand and freshwater. The synergistic effects of these components on the mechanical properties, microstructural characteristics, and environmental performance of ECC were thoroughly examined. The results showed that LC 3 incorporation notably improved mechanical performance, with compressive strength increasing by up to 60.93 %. Tensile properties also improved, with strain capacity increasing by 82.38 %, and the number of cracks increasing by 39.4 %. Additionally, strain energy grew by 115 %, peak stress improved by 27.9 %, and frictional forces between fibers and the matrix strengthened by 45 %. Microstructural analysis revealed the development of additional hydration products in LC 3 -based blends, such as Friedel’s salt, C-A-S-H, C-S-H, and carboaluminates, contributing to a refined pore structure. The sustainability evaluation demonstrated that LC 3 -based ECC significantly reduced CO₂ emissions, with reductions of up to 71 % per unit tensile strain and 52 % per unit tensile strength compared to reference specimens. Additionally, energy consumption decreased by up to 56 % per unit tensile strain and 38 % per unit tensile strength in comparison to the reference specimens. Among the tested formulations, LC 3 -50-SS-SW provided the best balance of mechanical performance, microstructural enhancement, and carbon-neutral potential. The comparative study demonstrates that properties such as the ratio of tensile strength to compressive strength and strain capacity in the current work are not only comparable to, but also surpass those of LC 3 -ECC from previous studies, all at the same compressive strength levels. These findings underscore the significant potential of LC 3 , SS, and SW as essential components in the development of high-performance, eco-friendly ECC, exhibiting superior engineering performance. • LC 3 based SS-SW-ECC exhibited a tensile strain of up to 11 % and a compressive strength of 79 MPa. • The pore structure was refined through the formation of additional hydration products. • LC 3 and SS-SW represent a promising solution for sustainable and high-performance ECC.