Feasibility of using seawater to produce ultra-high ductile cementitious composite for construction without steel reinforcement

摘要

Using seawater as mixing water to produce concrete may lead to excessive chloride content inside cementitious paste. This dramatically increases the risk of steel corrosion in the service life of RC structures. To address this issue, the authors tried to develop cementitious composites with sufficient ductility and strength, making it a structural material free from steel reinforcement, so that seawater can be used freely in mixture. In this article, ultra-high ductile cementitious composites (UHDCC) were fabricated using 100% natural seawater, sea-fresh water (50+50%) and 100% freshwater, in which the water-soluble chloride contents reached 0.288, 0.181, and 0.073%, respectively. Mechanical test results indicated that the presence of chloride ions has negligible influence on the strength of single polyethylene fiber and fracture toughness of UHDCC matrix. Also, no significant difference was found existing in tensile strength, tensile strain capacity, and composite bridging capacity of the UHDCCs mixed with seawater or freshwater. Four-point bending test demonstrated that plain UHDCC beams mixed with seawater, sea-fresh water or freshwater have the similar load bearing capacity to a reference RC beam having steel reinforcement of 0.57%. Generally, the present experimental study demonstrates that chloride content has negligible influence on the mechanical properties of UHDCC, thus providing a solution for concrete constructions located in coastal areas and isolated islands.