Title: Relationship between Washout Resistance and Rheological Properties of High-Performance Underwater Concrete

Author(s): Kamal H. Khayat and Joseph Assaad

Publication: Materials Journal

Volume: 100

Issue: 3

Appears on pages(s): 185-193

Keywords: admixture; rheology; underwater concrete

DOI: 10.14359/12618

Date: 5/1/2003

Abstract:
Antiwashout admixtures (AWAs) are mostly organic polymers incorporated into concrete intended for underwater placement and repair to reduce the risk of water dilution and separation of solid constituents. Such polymers are also used for highly workable concrete proportioned to flow under its own weight and self-compact with minimum segregation. This paper investigates the effect of two commonly used AWAs on washout resistance and rheology of highly flowable concrete. Test results show that for mixtures with fixed slump consistency, the incorporation of an AWA can greatly reduce water dilution and increase flow resistance and plastic viscosity of the concrete. These results are more accentuated at relatively high concentrations of AWA. Slump consistency cannot reflect the degree of washout resistance of AWA concrete. Washout resistance, however, is found to vary with the rheological parameters of the concrete calculated from the Bingham model. Rheological workability zones are defined for flow resistance and torque plastic viscosity combinations that can correspond to various levels of washout resistance. The V-funnel flow time test is shown to correlate well to plastic viscosity of highly flowable underwater concrete and, hence, can be useful to assess the impact of AWA on washout resistance in the field.