Durability of adhesively bonded timber-concrete-composite constructions joined by fast heated structural adhesive bond lines

Adhesively bonded timber-concrete composites (ATCCs) combine the specific material characteristics in an advantageous way and bring benefits regarding efficient material use, lightweight design, increased prefabrication and quality, as well as a faster construction progress. A vital aspect in this field is the durability of the adhesive connection, especially when used in building constructions. Currently, however, no standard testing methods for ATCCs have been identified. Therefore, this study aims to take a first step in investigating the durability of the adhesive bond of timber and concrete. On the basis of a literature review, three different experimental campaigns were conducted, covering tests in a climatic chamber with a combination of mechanical loading and moisture-induced stresses due to varying temperature and moisture content as well as delamination tests. The results indicate that three of the four adhesives and in particular the material combination of spruce and concrete are suited to bond timber and concrete, whereas the material combination of spruce and concrete requires more research. Moreover, the test-methods which have been applied for can be identified as suitable for investigating the durability of ATCC bond lines.The merging of the ATCC specimens was performed with a new hot-curing approach in which the heating of the adhesive joint is performed by an electrically conductive, thin adhesive tape that is heated by an electric power supply and investigated in combination with precoatable as well as established structural adhesives. As a reference, ATCC specimens with the traditional cold-curing approach were investigated as well.