Performance of Low-Slump Underwater Concrete Incorporating Antiwashout Admixtures (05-0328) - MP-14
Dina Adel Nakhla, Siemens Ltd Egypt
Mohamed Nagib Abou-Zeid, American University in Cairo, Egypt

Antiwashout admixtures (AWAs) are among recently employed techniques to minimize adverse effects associated with concrete placement underwater. However, relatively little work has been conducted on the influence of AWAs on performance of underwater concrete and evaluating the validity of conventional and non-destructive testing employed. Thirty mixtures were prepared with several water-to-cementitious materials ratio, admixtures types and dosages. Concrete specimens were placed in-air and at two underwater depths. The testing program involved fresh, hardened and non-destructive testing of concrete. A simple method was employed for the assessment of concrete and corrosion damage upon exposure to wetting and drying cycles in aggressive saline solution. Impact of the type and dosage of antiwashout admixtures, mix proportions and placement depth on fresh and hardened concrete properties is highlighted. Results suggest that the surface of underwater concrete has inferior quality to its core and that a need exists for adjusting and calibrating non-destructive methods when evaluating such concrete. Underwater AWA concrete exhibited relatively high susceptibility to damage when exposed to saline solutions.