Feasibility of using Waste Brine/Seawater and Sea Sand for the Production of Concrete: An Experimental Investigation from Mechanical Properties and Durability Perspectives

The anti-corrosion property of fiber reinforced polymer (FRP) makes the concrete produced with marine wastes (waste brine after desalination) and resources (seawater and sea sand) a promising green structural material which can be a sustainable solution to fresh water and river sand scarcity in marine and offshore construction. To evaluate the feasibility of using waste and marine resources in concrete, this study investigated the mechanical properties and durability of brine-sea sand concrete (BSC) and seawater-sea sand concrete (SSC) with three different water-to-cement ratios and compared them to the corresponding ordinary concrete (OC). The results demonstrated that the increased salinity had a minor effect on the 28-day compressive strength, but a significant effect on the large-size capillary pore structure. The semi-quantitative analysis of the concrete phase based on the X-ray diffraction (XRD) and thermogravimetric analysis (TGA) revealed that BSC and SSC had larger mass fractions of the amorphous phase (mainly C-S-H), ettringite and gypsum during hydration. At last, the comprehensive performance of three different concrete mixtures was evaluated by five indexes (workability, alkali environment, compressive strength, carbonization resistance, and sulfate resistance). The results show that it is feasible to use brine/seawater and sea sand to replace freshwater and river sand for marine structural concrete reinforced with FRP.