Performance of Low-Slump Underwater Concrete Incorporating Antiwashout Admixtures

Abstract

Antiwashout admixtures (AWAs) are among the agents recently used to minimize the adverse effects associated with underwater concrete placement. However, relatively little work on the influence of AWAs on the performance of underwater concrete and evaluation of the validity of the conventional and nondestructive test methods used has been conducted. Thirty mixtures were prepared with several water-to-cementitious material ratios, admixture types, and dosages. Concrete specimens were placed in air and at two underwater depths. The testing program involved fresh and hardened concrete testing as well as nondestructive testing. A simple method was used to assess the concrete and the corrosion damage on exposure to wetting and drying cycles in aggressive saline solution. The impacts of the type and the dosage of the AWAs admixtures, mix proportions, and placement depth on fresh and hardened concrete properties are highlighted. The results suggest that the quality of the surface of underwater concrete is inferior to that of its core and that there is a need to adjust and calibrate the nondestructive testing methods when such concrete is evaluated. Underwater AWA concrete exhibited relatively high degrees of susceptibility to damage when it was exposed to saline solutions.