Assessment of the performance and compatibility of acrylic polymer and silane based consolidants on deteriorated heritage masonry units subjected to salt weathering

Abstract

Heritage structures are susceptible to deterioration as they age naturally and are exposed to severe environmental conditions. One way to prolong the lifespan of these structures and reduce the rate of deterioration is through the application of consolidative treatments. This treatment acts by penetrating the permeable surface of the substrate and attempt to increase cohesion among the grains and reduce the impact of adverse environmental conditions. However, ensuring compatibility between the consolidant and the substrate is complex, which depends on the substrates’ material characteristics and its exposure conditions. If the wrong consolidant is chosen, it can accelerate deterioration instead of restoring the structure. This study aims to evaluate the effectiveness and compatibility of two types of commonly used consolidants, namely acrylic-polymer and silane-based consolidants, on samples of stone and fired clay bricks of varying qualities and characteristics commonly found in heritage masonry structures. The performance of the consolidants is assessed by comparing the initial physical, mechanical and microstructural properties of the substrate samples obtained through various testing methods, with the properties of treated and untreated samples after being subjected to accelerated weathering in order to analyze the weathering resistance. After which, a secondary comparison is made by treating the weathered untreated samples in order to assess the extent of restoration that happened when the consolidants are applied to the damaged samples. The results obtained from this study will guide decision makers who wish to use silane or polymer based consolidative treatments on heritage structures so that they can understand what kind of results to expect with respect to the substrate and the properties it possesses. From this they can make informed decisions to choose the treatment best for them in order to address their respective needs.