Experimental study of bond behavior on sprayed and poured mortar–brick interface with latex bonding agent under conventional and humid environments

Abstract

Sprayed mortars are able to enhance masonry walls, particularly for improving the resistance of the existing building stock to horizontal forces such as seismic. This is the case of numerous neighborhoods around the world constructed using load-bearing masonry walls before the 1950s. These mortars are sprayed on site and, to strengthen the interface, for example, latex interface bonding agents are applied between the sprayed mortar and masonry walls. Latex, being sensitive to ambient humidity, undergoes changes in its mechanical properties that directly impact the entire structure of the enhanced wall. But this crucial influence of ambient humidity on the latex layer has often been scarcely analyzed in previous studies. To overcome this gap, this research paper conducts an experimental investigation on the interfacial behavior under different humidity curing environments. It also compares interfaces formed through pouring and spraying methods. Several samples with latex interfacial bonding agents were tested using direct tension and direct shear tests to obtain stress–strain curves. Bond strength, fracture energy, and stiffness were determined using the traction separation method (TSL). This experiments found out that ambient humidity conditions significantly affected interfacial properties. In most cases, conventional curing environments resulted in higher peak stresses and fracture energies compared to humid conditions. Overall, sprayed mortar samples exhibited better interfacial properties than poured ones. Sprayed mortar samples demonstrated higher overall stiffness. The experimental results were fitted using three TSL models, with Schneider’s model providing the most accurate representation of interfacial behavior after optimization.