Experimental Investigation of One-Sided Strengthening Interventions on Historic Brick Masonry Walls

The conservation and restoration of historic buildings is a complex problem that requires an interdisciplinary approach in order to increase the bearing capacity of the structure while preserving the authenticity and aesthetics of the building. Despite its high diversity of built heritage, the city of Timisoara, located in the western part of Romania, presents heritage buildings in a bad state of conservation, with significant decays of the exterior render. In order to preserve the identity of the historic part of the city, measures have to be taken soon. Since commonly used strengthening solutions can alter the aesthetics of buildings and insulating materials can cause multiple problems, other solutions had to be taken into consideration. One particularity of Timisoara and Romania, in general, is that almost all apartments in historic buildings are privately owned, with each apartment having a different owner. This makes interventions that affect both sides of the external walls difficult. Therefore, a decision was made to investigate the effect of strengthening solutions applied only outside, as the owners rarely agree to move out of the building while interventions are made. To investigate the effect of the considered solutions, several experimental tests have been performed. The focus was decided to be on structural behavior under in-plane loads, of 1.2 × 1.2 × 0.45 m historic masonry brick wall samples with lime-based mortar, with and without different strengthening interventions. Since the main objective of the study is to identify appropriate strengthening solutions that would lead to aesthetical rehabilitation of buildings while not ignoring their social context, the following interventions were considered: steel mesh reinforcement with standard lime-based matrix applied on one or two sides. Unreinforced specimens were also produced as a baseline for comparison. All strengthening interventions were placed on wall samples without structural damage in order to better understand the effect of the materials used. To validate the results, three different samples of each scenario were tested during the campaign. The tests are based on ASTM E519/E519M – 15. The results obtained for all the samples were subsequently evaluated and compared to understand their strengths and weaknesses, both from both structural and aesthetic point of view.