Abstract

Modern masonry structures, apart from having a load-bearing function, are more and more subjected to additional non-structural requirements related to, e.g., thermal insulation and moisture control. This has respectively led to the introduction of thermal break layers, in practice often executed using autoclaved aerated concrete (AAC) blocks, and damp proof courses (DPC) in masonry walls. These modifications have an impact on the mechanical characteristics of the masonry, such as the shear strength. In this paper, an extensive experimental campaign is therefore conducted on masonry triplets to investigate the initial shear strength of concrete block and clay brick masonry, including AAC blocks. The impact of the the presence of a polyethylene DPC layer is also studied. Moreover, the position of the DPC membrane is varied, i.e., directly on top of the brick (which is generally not recommended yet common in construction practice) and in the middle of the mortar joint. In total, 138 shear tests were performed according to the EN 1052-3 standard, with low to moderate precompression levels. The test results focus on the differences in friction angle, shear modulus, and friction coefficient. It is concluded that the presence of an AAC block decreases the initial shear strength to a value which is lower than the one assumed by Eurocode 6. Moreover, when adding a DPC membrane, the shear strength is reduced even further to almost zero, in particular when the membrane is not put in the middle of the mortar joint.

Highlights

  • Masonry structures are nowadays designed for a high thermal insulation level to reduce energy losses in buildings

  • The two mortars applied for all experiments are a general purpose mortar (GPM) which was a ready-mix mortar for most experiments, and a thin layer mortar (TLM) for the clay bricks with the highest tolerances and smallest range according to EN 771-1 [24]

  • The brittleness decreases for all samples when an aerated concrete (AAC) block is placed in the middle (‘CAN’ (Figure 6d), ‘TAN’ (Figure 6e), and ‘PAN’

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Summary

Introduction

Masonry structures are nowadays designed for a high thermal insulation level to reduce energy losses in buildings. On top of the AAC layer, a damp proof course (DPC) is placed to prevent water and moisture from entering or rising in the inner leaf of a cavity wall. If this damp propagation is not properly addressed, mold formation can occur inside the wall as well as degradation of the masonry units [3,4].

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