Abstract
Sprayed mortar or shotcrete is a construction technology that could enhance existing masonry buildings’ resilience by reinforcing low-safety load-bearing walls. Many factors affect the resistance of shotcrete-reinforced structures. One of the most important is the bond strength at the interface between the shotcrete and the reinforced wall. According to previous technical literature, bond strength usually has two evaluation criteria: shear and tensile strength. The experimental campaign described in this article focused on the bond strength between sprayed mortar and three masonry materials without the influence of normal force or constraint, as well as the roughness of these materials. The analysis of these tests focused on determining the relation between bond strength, roughness, and material strength. The analyses revealed that material strength has a more significant effect on bond strength than roughness, and bond strength is related to shrinkage of the materials. On the basis of previous theories, these researchers found that when there is no obvious influence due to normal force and constraint, the shear strength and tensile strength are different, and the shear strength is likely to be the cohesion force of the two materials. Finally, this article concludes with a novel logarithmic relationship between these strengths.
Highlights
Many European cities have a high percentage of masonry buildings, most of which can withstand their vertical loads safely but would not be able to withstand any considerable horizontal loads like seismic actions [1]
Shen et al [17], which relied on previous methods developed by Barton & Choubey [18] focusing on rock-rock interfaces, investigated in detail the relation between roughness and shear and tensile strength in the case of rock-concrete joints
The bond strength between masonry walls and reinforcing sprayed mortar is crucial to consider the composite behavior of reinforced unreinforced masonry (URM) for proper structural performance
Summary
Many European cities have a high percentage of masonry buildings, most of which can withstand their vertical loads safely but would not be able to withstand any considerable horizontal loads like seismic actions [1]. Schneemayer et al [14] studied the fracture-mechanical properties of samples composed of brick and mortar M5 to M30 with different interface surfaces using wedge splitting tests and obtained notch tensile strengths from 0.3 to 2.7 N/mm. Shen et al [17], which relied on previous methods developed by Barton & Choubey [18] focusing on rock-rock interfaces, investigated in detail the relation between roughness and shear and tensile strength in the case of rock-concrete joints. If there are connectors such as anchors between the shotcrete layer and the element on which the mortar has been sprayed, these connectors constrain the displacement and the stress increases because of the deformation by the body These connectors work like a normal force applied on the surface to increase the shear strength. The following sections present previous related research, the experimental campaign, its results, the analysis and discussion of the results and the conclusions
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