Preparation and mechanical characterization of cost-effective low-carbon engineered cementitious composites with seawater and sea-sand

Engineered cementitious composites (ECC) has superior mechanical properties, showing obvious deformation hardening and multi-cracking behavior under tensile and bending loads, and solving the brittleness problem of traditional concrete. The purpose of this study is to prepare cost-effective low-carbon engineered cementitious composites with seawater and sea-sand (SS-ECC), to solve the problem of freshwater and river sand shortage in coastal areas. Moreover, high-volume of fly ash and silica fume were used to substitute for the cement to reduce carbon dioxide (CO2) emissions of SS-ECC, and hybrid local polyvinyl alcohol (PVA) fibers and basalt (BA) fibers were used to reduce its cost. The effects of the sea-sand particle size (0.1-0.3/0.3-0.5/0.6-1.0 mm), the hybrid BA fiber length (6 mm and 12 mm), and the hybrid BA fiber volume fractions (0.1/0.2/0.3%) on the mechanical properties of SS-ECC specimens were studied. In addition, a new flexural toughness evaluation method is used to evaluate the bending properties, and the index of tensile properties is evaluated by calculating the tensile strain energy density. The results show that increasing sea-sand particle size and using 6 mm BA fibers instead of PVA fibers with equal volume content will reduce mechanical properties of SS-ECC. However, increasing the length of hybrid BA fibers can improve the bending and tensile properties of SS-ECC. The results of this study support that the SS-ECC can be more widely used in practical engineering applications in coastal areas.