Modeling steel-concrete bond strength depletion during corrosion

Copyright © 2018, American Concrete Institute. All rights reserved. Corrosion propagation is significant during the service life of concrete. This paper reviews the parameters that impact on the steel-concrete bond and a displacement function was developed describing the cracked concrete. The Critical Corrosion Penetration Depth (CCPD), defined as the corrosion sufficient for cracking, was derived. CCPD depends on concrete material properties, largely on rust volume expansion rate, and how the rust is deposited in the concrete: Leading to a sensitivity analysis of these parameters. Three rust deposition hypotheses were analysed: 1) partial deposition of the rust into an open crack; 2) rust remains at the corroding bar; and 3) partial deposition of rust within a porous zone at the bar-concrete interface. The models were compared with published laboratory test data, with Model 3 matching most closely. A new predictive model is proposed, describing the corrosion-bond strength relationship, with varying reinforcing bar diameters and cover thicknesses. Predicted results compared well with test data.