Mechanical Strength and Toughness Performance of Seawater Sea Sand ECC with Variable Polyethylene Fiber Content and Length

Seawater sea sand-engineered cementitious composites (SS-ECCs) provide a potential solution to the shortage of freshwater and sand resources for coastal and offshore construction. However, systematic studies on the combined effects of fiber parameters in SS-ECC systems remain limited. This study examines the effects of polyethylene (PE) fiber content (0%, 1%, 1.5%, and 2%) and length (12 mm, 18 mm, and 24 mm) on the mechanical properties of SS-ECC via compressive, tensile, and bending tests. The results indicate that increasing the volume fraction of PE fibers effectively enhances the tensile strength, flexural strength, and flexural toughness of SS-ECC. SS-ECC attained its highest tensile strength with a 24 mm PE fiber length, showing increases of 41.1% and 44.2% over specimens with 12 mm and 18 mm fibers, respectively. Furthermore, based on 28-day curing, the utilization of seawater and sea sand led to increases in tensile and flexural strengths by 12.3% and 17.2%, respectively, relative to ECC prepared with freshwater and river sand, though it resulted in a reduction in toughness. A predictive model for tensile strength is established considering the characteristic value of PE fiber with an R2 of 0.8461, indicating reasonable correlation within the tested range. Results from this paper can help to develop a favorable PE fiber-reinforced SS-ECC for ocean engineering.