Underwater Concrete Placement

Concrete and grout for underwater placement requires a mixture design that flows easily while staying cohesive to provide proper consolidation and to prevent the washout of paste. Excessive washout compromises both the strength of the hardened concrete and grout and also may raise the pH of the marine environment to levels that are harmful to the ecosystem. Self-consolidating concrete (SCC) and grout amended with a viscosity modifying admixture (VMA) could provide the needed wash-out resistance and facilitate proper consolidation. This project will study the performance of both concrete and grout mixtures with and without self-consolidation as well as various types of VMAs in an underwater environment. The goal of the project is to optimize these concrete and grout mixtures to be resistant to washout and segregation underwater and to develop a Virginia Department of Transportation (VDOT) special provision which indicates effective practices for underwater concreting and grouting.