Peer-to-Peer Webinar: Conservation of Heritage Structures

Speaker 1: Dr Swathy Manohar, Indian Institute of Technology Bombay, India

Title 1: Material Properties - Keys to Enhance Salt Crystallization Resistance in Heritage Masonry Structures

Salt crystallization is one of the most prevalent causes of degradation in heritage masonry structures, affecting materials such as stones, bricks, and lime mortars. This talk will explore the key material properties that influence the extent of salt crystallization damage in these historical materials. The critical material parameters such as chemical composition, crystal morphology, pore size, and pore distribution will be analysed, discussing their roles in governing salt crystallization processes. Through an in-depth analysis of these factors, the importance of quantifying and understanding these material characteristics to develop effective conservation strategies will be highlighted. The presentation will also address the possibility of engineering building materials to improve resistance against salt-induced damage, drawing insights from studies on historical structures. This exploration aims to foster a deeper understanding of material science for the preservation of culturally significant heritage buildings.

Speaker 2: Anupama V.A, Indian Institute of Technology Madras, India

Title 2: Understanding Salt Weathering in Combined Brick-Mortar Masonry Systems

Salt weathering poses a substantial threat to India's architectural heritage, particularly affecting coastal monuments built predominantly from brick masonry. This deterioration process impacts both the aesthetics and durability of these structures, as they are continually exposed to a dynamic environment characterized by fluctuations in moisture, temperature, salinity, wind, and humidity, all of which accelerate their decay. Beyond mechanical damage through wear and tear, the porous materials of these buildings are susceptible to chemical effects like dissolution, hydrolysis, and the damaging cycles of salt crystallization precipitated by repeated episodes of moisture ingress and evaporation.
Salt crystallization, in particular, has been identified as highly detrimental, with the capacity to inflict damage that penetrates beyond the superficial layer, compromising material cohesion and structural integrity. This deep-seated damage necessitates focused research to develop effective conservation methods that ensure the longevity and functionality of heritage structures. Conservation efforts prioritize the selection of repair materials that not only support the structural integrity but are also compatible with the original materials to preserve historical authenticity. In laboratory settings, accelerated weathering cycles that alternate between wetting and drying are utilized to simulate real-world environmental conditions. These tests are crucial for evaluating the durability of different substrates and mortar compositions under salt exposure. This talk specifically investigates the performance of bricks and mortar formulations, exploring both individual and combined responses to these simulated salt weathering cycles. It also considers the impact of wind on their durability.  The research methodically examines the resilience of both composite brick-mortar samples and individual specimens of bricks and various mortars composed of cement, hydrated lime, fly ash, and limestone. Following a systematic weathering protocol, the study assesses their resistance to salt damage, monitoring mass changes throughout the cycles and conducting comprehensive physicomechanical, microstructural, mineralogical, and morphological characterizations to gauge their salt weathering resistance.

This webinar is brought to you by the RILEM Youth Council (RYC) and hosted by Surender Singh (South Asia RYC representative).