Experimental study on the mechanical properties of different fiber-reinforced seawater sea-sand engineered cementitious composites

•The influence of PVA fiber length on compressive and bending strength of SS-ECC was studied.•The PE and PP fiber-reinforced SS-ECCs had higher compressive strengths, but lower flexural strengths.•The PE fiber-reinforced SS-ECC achieved tensile strength of 4.047 MPa and tensile strain capacity of 3.023%.•The stress–strain curve for PE showed four distinct stages: elastic, elastoplastic, strain-hardening, and failure stage.•The toughness and residual strength indexes of PE fully satisfied the requirements of high toughness and high plasticity. Engineered cementitious composites (ECCs) are a type of fiber-reinforced cementitious composite featuring tensile multiple-cracking and strain-hardening behaviors. Fiber-reinforced seawater sea-sand engineered cementitious composites (SS-ECCs) are a new type of ECC used for construction in coastal and marine areas lacking fresh water and river or manufactured sand, offering SS-ECCs much potential and socioeconomic benefit. In this study, SS-ECCs were prepared with artificial seawater, natural sea-sand, different fiber types (polyvinyl alcohol (PVA) fibers, polyethylene (PE) fibers, polypropylene (PP) fibers) and different fiber lengths (6, 9, 12, and 18 mm). Compression, flexural, tensile and bending tests showed that the compressive and flexural strengths of SS-ECCs initially increased and then decreased with increasing fiber length. A fiber length of 12 mm yielded the maximum strength. The 12-mm PE fiber-reinforced SS-ECC displayed the largest ultimate tensile stress of 4.047 MPa and the largest ultimate tensile strain of 3.023%, and its flexural and tensile toughness indexes and residual flexural and tensile strength indexes all satisfied the corresponding requirements for an ideal elastoplastic material. In contrast, the 9 mm and 12 mm PVA fiber-reinforced SS-ECCs satisfied the requirements for an ideal elastoplastic material only partially. The relationship between the ultimate flexural deflection and the ultimate tensile strain is discussed, and the error of the formula between them is analyzed. All the findings can facilitate the future design and application of SS-ECCs in coastal and marine structures.