The effect of the addition of granite powder to the primer on the pull-off strength of epoxy resin coatings

This article describes the effect of adding waste granite powder to the epoxy resin layer on its pull-off strength. The substrate was C30 / 37 concrete. The priming resin was modified with 10%, 20%, 30%, 40%, 50%, and 60% of granite powder. For control purposes, a sample was also made without the addition of powder. For each material configuration, four strength tests were carried out with the use of an automatic device recording both the pull-off strength and the measurement time. The obtained results were compared with the control sample. The best result in the test was obtained with the addition of 20%, which gave an increase of 19% compared to the reference sample. An equally good result was obtained with the addition of 10% granite powder (increase by 11%). The addition of a larger amount of the additive resulted in a decrease or a slight increase in the pull-off strength compared to the reference sample. Additionally, the additive has been found to darken the coating, and the coating becomes completely opaque when added above 50%.