The current knowledge and building code recommendations for bond behavior between concrete and embedded steel reinforcement become unwarranted when casting takes place in humid or fully submerged water conditions. The main objective of this paper is to assess the effect of underwater casting on the concrete mechanical and bond properties, including the development of regression models that simplify prediction of washout loss and corresponding bond stress-slip properties. Washout loss was determined using the standard CRD C61 test method and air-pressurized tube that simulates higher hydrostatic water pressure. Particular care was placed to reuse the same washed concrete samples for determining the residual compressive strength and bond properties to embedded steel bars. Test results showed that the washout loss and hydrostatic casting depth are directly affected by the concrete composition. Hence, for example, the decrease in water-to-cement ratio and/or addition of anti-washout admixture or silica fume improved concrete cohesiveness and resistance to washout. The stiffness and confinement of steel bars normally achieved in dry conditions curtailed with underwater casting, which led to reduced ductility and ultimate bond strength at failure. The experimental bond stress-slip data are compared with the CEB-FIP Code models and design strengths specified by ACI 318-19 and European Code EC-2. Regression analysis and predictive charts are established to facilitate assessing the effect of concrete composition on washout characteristics and residual strengths following underwater casting.

当在潮湿或完全淹没的水中进行浇铸时，对于混凝土和嵌入式钢筋之间的粘结性能的现有知识和建筑规范建议将变得毫无用处。本文的主要目的是评估水下浇铸对混凝土力学性能和粘结性能的影响，包括开发回归模型，以简化对冲刷损失和相应粘结应力-滑移性能的预测。使用标准CRD C61测试方法和模拟较高静水压力的气压管确定冲洗损失。要特别注意重新使用相同的水洗混凝土样品，以确定残余抗压强度和与埋入钢筋的粘结性能。试验结果表明，冲蚀损失和静水浇铸深度直接受混凝土组成的影响。因此，例如，水灰比的降低和/或抗冲蚀剂或硅粉的加入改善了混凝土的粘结性和抗冲蚀性。钢筋的刚度和约束通常是在干燥条件下通过水下铸造来实现的，这导致延展性降低，破坏时的最终粘结强度降低。将实验的粘结应力滑移数据与CEB-FIP规范模型和ACI 318-19和欧洲规范EC-2规定的设计强度进行比较。建立回归分析和预测图表以方便评估混凝土成分对水下浇铸后冲刷特性和残余强度的影响。