Title: Simulation of Water Pressure on Washout of Underwater Concrete Repair

Author(s): Joseph J. Assaad, Yehia Daou, and Kamal H. Khayat

Publication: Materials Journal

Volume: 106

Issue: 6

Appears on pages(s): 529-536

Keywords: hydrostatic pressure; interfacial velocity; underwater concrete; washout loss

DOI: 10.14359/51663336

Date: 11/1/2009

Abstract:
A comprehensive research project was undertaken to evaluate the effect of hydrostatic pressure and interfacial concrete/water velocity on the performance of underwater concrete (UWC) designated for repair applications. Washout loss was determined on 33 optimized mixtures using the CRD C61 test method, as well as a newly developed device enabling the simulation of concrete washout placed at various depths down to 140 m (460 ft) below water surface level. Test results showed that washout loss of UWC increases with the increase in water head. Depending on the mixture composition, a critical threshold water depth can be found, beyond which significant washout loss could take place. The effect of decreasing the interfacial concrete/water velocity from 2.5 to 0.5 m/s (8.2 to 1.6 ft/s) was found to reduce washout loss for a given depth of casting or enable the casting in deeper water for a given washout resistance. Good correlations were obtained between washout loss determined as per the CRD C61 test method and the washout loss derived from estimates given a certain interfacial concrete/water velocity and water depth.