The influence of the substrate type on the performance of an industrial cement mortar for general use

Abstract

This work aims to analyze the influence of different substrates on the performance of a conventional industrial cement-based mortar. The main objective is to evaluate how different substrates influence the physical and mechanical characteristics of the applied mortar, considering that the performance of mortars is typically characterized in the laboratory without the influence of the substrate. The research methodology includes experimental data with statistical analysis (ANOVA) of the results. Several campaigns were carried out, which began with the detailed characterization of the industrial cement mortar under study and various substrates. At the same time, the mortar was applied to the substrates and, after hardening, was detached and characterized through the same tests. These tests were based on the standards, with the necessary adaptations due to the different mortar dimensions after detachment. As a result, it was possible to conclude that the substrates where a mortar is applied must be considered a variable in its composition, considering that they influence the final behavior of the applied mortar. After application to the substrates, the mortar's performance differs from that of standardized laboratory samples. It was also concluded that ceramic, concrete and lightweight aggregate substrates influence the mortar's characteristics differently, especially the open porosity and the average pore diameter. For ceramic substrates, the characteristic that seems to influence the behavior of the mortar is capillary water absorption; for concrete substrates, it appears to be open porosity. The possibility of a transfer of water between mortar and substrate generates local changes in the water content, affecting the binder concentration and the compactness of the mortar especially noted at the interface region. The study can contribute to selecting more compatible mortars and improving the performance of the applied mortars in real service conditions.