Evaluation of characteristics of adhesion strength between wood flooring and finish mortar for prevention of construction defects

Most residential buildings in Korea use floor heating, with wooden flooring often installed on top. The number of cases of poor construction owing to inadequate adhesion during the installation of such wood flooring is increasing. This study analyzed the pull-off strength of a ground surface with wood flooring, to reduce construction defects on the floor. An X-ray fluorescence (XRF) test on top of the finished mortar indicated a difference in composition before and after ground treatment, suggesting the existence of an abnormal surface layer. In specimens with a ground surface, the contact angle tends to be lower, thereby contributing to an improved absorption rate of the liquid adhesive through surface modification. Specimens subjected to the ground surface showed two to three times increase in the pull-off strength. The pull-off strength varied depending on the type of mortar. Specifically, basic floor plastering mortar exhibited a higher adhesive strength compared to high-performance floor plastering mortar before ground surface, with the opposite observed after treatment. Applying a ground surface approximately 1–2 mm from the mortar surface can effectively increase the pull-off strength, because the epoxy adhesive can be absorbed smoothly.