Influence of water currents velocity on the strength of a new underwater concrete approach

Despite significant progress has been achieved in the underwater concrete (UWC) technology properties depending on the traditional anti-washout admixtures, few researches have been conducted about the hardened concrete performance in flowing water. Based on experimental program, this study investigates the influence of moving water on the strength of the pouring underwater concrete, and discusses the influences of water cement ratio (W/C), superplasticizer (SP) and the type of water depending on the new technique named self-protecting underwater concrete (SPUC). SPUC approach depends on changing the water characteristics of water medium to make it suitable to receive the fresh concrete instead of incorporating traditional AWAs to the concrete blends. According to the experiments views, it is confirmed that the exposed surfaces of SPUC lead to more fine particles leakage and more strength loss however, SPUC achieved relative strength higher than 90 % during moving water. Also, the optimum strength was recorded at W/C and SP at 0.42 and 1.13 respectively. Furthermore, it is recommend to pour SPUC as fast as possible with water velocity less than 0.5 m/s to achieve less dispersible and aggregate segregation. Additionally, the salinity of water has a little effect of the 28 days strength and SPUC achieved higher strength than conventional UWCs relatively.