Title: Effect of Washout Loss on Bond Behavior of Steel Embedded in Underwater Concrete

Author(s): Joseph J. Assaad and Camille A. Issa

Publication: Structural Journal

Volume: 110

Issue: 3

Appears on pages(s): 511-520

Keywords: bond properties; segregation; underwater concrete; washout loss

DOI: 10.14359/51685608

Date: 5/1/2013

Abstract:
Limited studies have been undertaken to investigate the bond properties of reinforcing steel bars embedded in underwater concrete (UWC). Approximately 60 pullout tests were carried out to evaluate the effect of washout loss (W) on residual compressive and bond strengths. Washout was determined using the CRD C61 test and by simulation using a newly developed air-pressurized tube. Reference mixtures sampled in dry conditions were also tested. Test results showed that bond between steel and UWC is affected by a combination of parameters that complement those documented in the literature for concrete cast and consolidated above water. These include the level of W, degree of segregation, hydrostatic water head (H), and interfacial concrete-water velocity. The bond-stress-versus-slip behavior of UWC is remarkably different from the one obtained using reference mixtures. Initially, the linear response is less stiff due to a coupled effect related to lower strength and increase in the relative coarse aggregate concentration. The slip at ultimate bond strength was found to decrease for UWC mixtures exhibiting higher levels of W.