Residual Strength of Organic Anchorage Adhesive for Post-installed Rebar at Elevated Temperatures and After Heating

A series of pull-out tests for anchorage adhesives were carried out at elevated temperatures of 25°C, 60°C, 100°C, 160°C, 260°C and after heating. The heating process followed a fixed curve. Three commonly used anchorage adhesives were adopted and five specimens were tested at each temperature condition. The residual strengths of the connection in and after heating were analyzed and compared. The force-slip relationships of the adhesives at elevated temperatures and after heating indicated that the bond strength decreased remarkably with the increase of temperature but recovered slightly after heating. The bond properties and failure mechanism between the adhesive bar and the outside tube are discussed. A three-stage and four-stage models for force-slip relationship were obtained by curve-fitting. The bond strength variations with the increasing of the deformation at the elevated temperature and after heating were contrasted. The results shown that bond strength of anchorage adhesive is strongly dependent on temperature and it decreases rapidly with rising temperature, the residual bearing capacity of anchorage adhesives is around or lowers to 10% when the temperature exceeds 260°C and the vinylester adhesive is more sensitive than epoxy adhesive to temperature effects. The result also shown that the glass transition temperature was a useful metrology for behaviors of adhesive after heating and it can also be used to determine the upper limit temperature for continuous application.