Enhanced adhesive performance of epoxy resin coating by a novel bonding agent

Abstract The current paper aims to propose a novel epoxy resin bonding agent for improving the bonding strength of epoxy resin coating systems. These kinds of systems are mainly employed during the repair and maintenance of existing cement-based structures, especially concrete floors. The paper presents the results of a series of tests of epoxy resin coatings, in which the matrix of the bonding agent made of epoxy resin is modified with the addition of coconut fibers. Pull-off strength tests were performed on the cement paste and cement mortar substrates. The results presented that the addition of 0.5%-1.0% of coconut fibers to the bonding agent matrix resulted in increased pull-off strength of the coating. In turn, it was observed that in the case of using a higher volume fraction of fibers the occurrence for the delamination failure between the epoxy resin and substrate was more pronounced. This is manifested by the reduction of the pull-off strength of the epoxy resin coating and is probably caused by the increased presence of fiber clusters in the epoxy resin matrix. Finally, to confirm the obtained macroscopic results, the specimens were analyzed using the scanning electron microscopy method by examining the interface between the coating and substrate. Numerical simulations were successfully predicting the behavior of pull-off strength using simplified concrete damage plasticity. The linear behavior was defined for presenting the softening behavior of the substrate during loading.