Mechanical Performance and Constitutive Model Analysis of Concrete Using PE Fiber-Strengthened Recycled Coarse Aggregate

To promote the sustainable development of the construction industry, concrete incorporating polyethylene (PE) fiber-strengthened recycled coarse aggregate (SRCA) and seawater and sea sand (SWSS) is prepared. The usage of SRCA significantly improves the mechanical performance of concrete. The strength is improved, and the failure mode of concrete cylinders is also remarkably altered. The incorporation of SWSS that alleviates the shortage of freshwater and river sand slightly reduces the mechanical strength of concrete at 28 and 90 days, while the replacement of cement by 35% limestone calcined clay cement (LC³) overcomes this drawback. The compressive strength of concrete is further enhanced, and the pore structure is refined. The introduction of LC³ also promotes the formation of Friedel's salt, which could improve the chloride binding capacity of concrete using SWSS. Furthermore, the stress-strain relationship of sustainable concrete is analyzed, and the experimental results are compared with the commonly used constitutive models. The predictive constitutive models are proposed to effectively describe the mechanical performance of sustainable concrete.