Modeling of Bonding for Epoxy Resins between Steel Rebar and Concrete at Elevated Temperatures

Epoxy resins have increasingly been used to bond steel rebars into existing cast-in-place or precast concrete structures due to the advantage of higher bond strength compared with mechanical steel-to-concrete anchors at normal temperature. At elevated temperatures, however, significant bond deterioration can be expected as the resin’s modulus decreases with an increase of temperature. The decrease in the load bearing capacity of the bond can lead to collapse of the structural systems after exposure to high temperatures.

A mechanical model is proposed in this study to investigate the characteristics of the adhesive bonding stress between steel rebar and concrete interface at elevated temperatures. The model is calibrated with the results obtained from a series of pull-out tests using deformed bars with varying diameters of 12 mm, 16 mm, 20 mm and 25 mm. It is found that the model provides good prediction of the bond stress.