In Brazil, the execution of cement-based render by using the wet spraying method using rotor-type machines has grown in recent years. Despite the potential of this system to contribute to improve the quality of rendering, the different execution procedures employed during its production still have not been systematically evaluated. The aim of this paper is to evaluate the influence of a set of variables - the moisture condition of the substrate; moisture content of the mortar; thickness and number of coats; time interval between coats; and application technique of the mortar; and surface finishing technique - on the rendering behavior, more specifically on initial bonding, cracking and adhesion, through experimental evaluation. The results led to the conclusion that the mechanical projection of mortar promotes a significant increase in adhesion when compared to manual application and that the surface finish technique called scraping can significantly impair the behavior of these renderings. Furthermore, the substrate moisture condition, the mortar moisture content, and the time between coats are variables that strongly interact and positively or negatively influence the behavior of these coatings.
External cement based render; Mortar spraying; Rendering behavior; Adhesion strength; Initial bond; Cracking
