The effects of strengthening the AAC walls using glass mesh arranged in different configurations

The usage of AAC (Autoclaved Aerated Concrete) blocks for the construction of new masonry structures, particularly low-rise residential buildings, has become very popular in Poland. It provides an uncomplicated erecting method, which is characterized by thin bed joints and unfilled head joins, but at the same time, makes these walls very sensitive to any internal tensile stresses, causing damage with varying intensity. To avoid premature cracking, leading to a brittle failure of existing walls, an external strengthening can be an acceptable and effective solution. Taking into account that AAC units are a natural material, the application of a FRCM system (instead of FRP) is more suitable here. This system uses a mineral-based matrix that provides congenial compatibility with a masonry substrate. This study presents an analysis of the influence of superficial strengthening on the behaviour and deformability of masonry walls made of AAC blocks. A typical glass mesh (most often used in thin external plastering) and mineral mortar dedicated to renovation works are used as strengthening materials. The specimens are strengthened unilaterally (two types) or bilaterally and are subjected to diagonal compression according to the RILEM 76-LUM standard. The consecutive work stages, shear strains and modes of failure are described and discussed.