Influence of brick and concrete substrates on the performance of renders using in-situ testing techniques

Abstract

The real performance of renders is influenced by several in-service factors. To analyze this influence two types of mortars - a traditional mortar (1:4 cement:sand in volume) and an industrial one-coat mortar - were applied on ceramic and concrete substrates, whose surface has been previously treated in three different ways: i) without moisture; ii) with double spraying of water, iii) with water immersion for 4 h. Through in-situ testing techniques (ultrasound, pendulum sclerometer and Karsten tube) at 28 and 90 days of age it was possible to discuss how the substrate and its suction influence the experimental results. When evaluating the performance over this period, it was possible to conclude that the applied mortars improved, in general, their mechanical behavior. In terms of preparation of the substrate, a double spray of water on the substrate surface achieved the best performance for both substrates. With the testing techniques it was found that the substrate and its suction had a significant influence on the performance of the applied mortars.