Influence of substrate texture on the tensile and shear bond strength of rendering mortars. (15th December 2016)

• Record Type: Journal Article
• Authors: Stolz, Carina M.; Masuero, Angela B.; Pagnussat, Daniel T.; Kirchheim, Ana Paula
• Is Part Of: Construction & building materials. Volume 128(2016)
• Page Start: 298
• Page End: 307
• Publication Date: 2016-12-15
• Subjects: Tensile bond strength -- Shear bond strength -- Substrate texture -- Mortar renders -- Rheology; Building materials -- Periodicals; 624.18
• DOI: 10.1016/j.conbuildmat.2016.10.097
• Languages: English
• ISSNs: 0950-0618

Abstract

Highlights: Concentrations of an air-entraining admixture on the contact area is investigated. The influence of substrates textures on the contact area is analyzed. Rheological behavior of mortars is observed whit squeeze-flow tests. The tensile and shear bond strength are statistically analyzed. Laser Scanner 3D is identified as promising method to quantify real contact area. Abstract: This study assessed the influence of the substrate texture and rheological characteristics of mortars on the shear and tensile bond strength of rendering mortars. Concrete slabs with three different types of surface textures were used as substrate. Rendering mortars were prepared with a composition of 1:1:4 (cement: hydrated lime: dry sand, in volume – converted to mass), water/binder ratio 1.2, with different concentrations of an air-entraining admixture (0, 0.2 and 0.5%), and sand with a controlled granulometric composition, to modify the rheological properties of this material. These mortars were placed on the substrates using a device to control the force of application. The results showed that increasing the contact area in the substrate, as a result of different surface textures, does not always increase the bonding strength between the substrate and the render. Instead, the rheology of the rendering mortars seems to be the main factor controlling their bonding capacity. Depending on the substrate texture, rendering mortars with different consistencies increase the bonding strength of this type of systems. Also the workability of the rendering mortars, considering the roughness of the substrate, needs to be optimized to ensure a long-lasting life of the rendering.