Assessment of Epoxy Resins for Injected Bolted Shear Connections

Abstract

Abstract The purpose of this thesis is to assess potential alternative epoxy resins in injected bolted shear connections for a civil engineering application. Research has focused on the application of injection bolts with various resins in a double lap shear connection. In current practice only one resin is allowed to be used due to regulation by RWS. This is RenGel SW404/HY2404 resin [1]. To assess possible alternatives different products have been selected that have potential for use in this application. To verify their performance, short duration double lap shear tests have been performed in the Stevin Laboratory. The curing temperature of the resin was varied in testing to assess the influence this has on performance, and gain further insight in the importance of material properties of resins for injection bolts. Secondly the stress distribution of the resin layer has been investigated by developing an analytical model using 1 dimensional Timoshenko beam theory. This model was calibrated using results from lab tests and verified against FEM results and other experiments. From this research, it is concluded that only Edilon Dex R2K resin is a possible alternative resin. The injection procedure is simplified with this product but it suffers from large scatter in results in this research. The found characteristic short term strength is 156 MPa when cured at 16 degrees Celsius. Curing temperature had no influence for RenGel SW404/HY2404 between 8 and 24 degrees. Dex R2K did have a positive dependency in this range. Lastly the research into the effect of bolt length shows a trend that the connection capacity remains the same or increases slightly for L/D ratios above 3. From this research, it is recommended to gain further insight in the mechanical behavior of injection bolt connections through FEM analysis. Furthermore, development of alternative washer designs and research into optimized injection procedures are recommended. Lastly the occurrence of air inclusions in the resin layer as noticed in this research is something to be investigated in future research.