Effect of heating rate on bond failure of rebars into concrete using polymer adhesives to simulate exposure to fire

The high bonding capacity of polymer adhesives has encouraged their application for anchoring steel bars into concrete for structural purposes. However, high temperatures have the effect of weakening the bond and endangering the construction under a fire situation. This paper evaluates bond resistance to temperature by means of pull-out tests performed with a constant tensile load on the steel bar and a progressive temperature increase of the bond throughout the test until a failure temperature is reached. Two testing programs were performed using separate heating technologies: electric oven and gas furnace, which mainly differ by their heating speed, in order to assess the influence on bond failure at high temperature. The study describes thermal characteristics and phenomena such as vaporization in different concrete zones near the anchor in both of the testing devices (electric and gas).