Durability of Heritage Masonry Structures: Review on the Substrate-Mortar Interaction: Fid-Bau Portal

Durability of Heritage Masonry Structures: Review on the Substrate-Mortar Interaction

Anupama, V. A. / Santhanam, Manu

Much of the built heritage stock comprises masonry units of stone or brick, adhered by lime mortar. The properties of the materials used in the construction play a pivotal role in the strength and long-term durability of the masonry structures. The breathability of lime mortar, the porosity of substrates, and the properties of the substrate-mortar interface are critical to the extended serviceability of the structure. The current study focuses on a review of the substrate-mortar interface properties developed over short-term and long-term durations. The fundamental mechanisms of adherence and material transport across the interface were studied in detail. Analysis of physico-hygro-thermal influences on masonry structures was found to give crucial insights on the porosity and pore size distribution of the unit, mortar and the interface. The mortar properties such as water content and composition were found to have a significant impact on the bond strength development. The microstructural investigations using characterization techniques confirmed that the network of products formed at the interface by hydration and carbonation also governed the interface porosity. The study on the weathering characteristics that modify the transport parameters is critical for understanding the fundamental principles behind moisture attack and salt crystallization in ancient structures, typically on coastal monuments. The study provided a comprehensive insight into the transport mechanisms and the critical parameters for consideration during the design of mortars for restoration.