Adhesive bonding of timber-concrete composites with integrated heating for accelerated curing of a two-component epoxy adhesive

Adhesive bonding of timber – concrete composites (TCC) offers improved structural performance compared to mechanical connectors but is often limited by slow curing under ambient conditions. This study investigates the suitability of the two-component epoxy adhesive SikaPower®-880 for temperature-assisted bonding using integrated conductive heating. Curing behavior was analyzed by differential scanning calorimetry (DSC) and rheology, while tensile tests on bulk adhesive specimens and compressive-shear tests on TCC specimens evaluated mechanical performance. The results demonstrate a strong temperature dependence of curing kinetics. Increasing the curing temperature from 60°C to 80°C reduces the time to reach a degree of cure of α = 0.7 from approximately 26 min to 12 min. Compared to ambient curing (23 °C), where similar conversion requires hours to days, this represents a substantial acceleration. The glass-transition temperature (Tg) increases with curing temperature up to 80°C, consistent with increased cross-link density. At higher temperatures, thermally induced degradation occurs, indicated by reduced Tg, decreased tensile strength, and porosity formation. At the structural level, curing at 80°C improves characteristic shear strength and reduces scatter. The results indicate that curing at approximately 80°C provides an effective balance between accelerated curing and avoidance of thermal degradation.