Strength evaluation of a new underwater concrete type

A comprehensive research study was conducted to evaluate the compressive strength of a new underwater concrete (UWC) type, commonly referred to as self-protected underwater concrete (SPUC). As the compressive strength is generally considered an essential characteristic of the performances of hydraulic and marine structures, especially because it is affected by the washout rate, the compressive strengths of SPUC were determined using the same concrete mixtures as those used for the SPUC washout loss tests. The concept of SPUC is different from that of the conventional UWC because it depends on the alteration of water characteristics in conjunction with the use of an underwater protective agent (UPA), such that the water medium can be readily available to receive fresh self-compacted concrete without mass loss. In addition to the air specimen, a strength test was conducted with freshwater and seawater specimens. The test results showed that the relative compressive strengths reached values equal to 90% and 88.48% for seawater and freshwater, respectively. These findings are compatible with the washout measurement outcomes. In addition, it is notable that the optimum slump flow for the compressive strength of the SPUC should not exceed 650 mm. Furthermore, the 28-day strength can be inferred from the 7-day strengths of freshwater and seawater. •SPUC showed significant compressive strength efficiency.•UPA has been proved to be an environment-friendly anti-washout admixture.•Compressive strength and SPUC washout test results are in good agreement.•The strength of SPUC is higher in seawater than in freshwater.