Mortar cure-dependent effects on adhesive anchor systems loaded in tension

This paper presents a large experimental campaign and the corresponding analysis quantifying mortar curing effects on the pull-out performance of bonded anchor systems. Standard confined pull-out tests were performed on two commonly used adhesive anchor systems. The two investigated bonded anchor systems were based on different materials, where the mortar of the first bonded anchor system (BAS-VE) was a vinyl-ester based product and the second bonded anchor system (BAS-EP) contained an epoxy-based mortar. In order to isolate the mortar curing effects on the anchor performance, a mature concrete was used as base material minimizing well-known aging and curing effects related to the substrate, concrete. In total, 93 pull-out tests were performed for various curing times in order to characterize influences on bond strength, stiffness, and peak displacement. Depending on the product specifications and corresponding approval documents, tests were carried out in a time-range of a few minutes up to three months after the anchor installations. Measured temperature (and humidity histories) of the environment have been utilized for predicting the mortars’ degree of cure for each structural anchor test. The results show a cure-dependent behavior in BAS-VE and BAS-EP. Although the bond strength fails to increase significantly after reaching the manufacturer approved minimum curing time, the stiffness shows an increase for longer cured anchors.