Impact of Natural Fiber and Fatty Acid Organic Additives on the Permeability of Lime Mortars for Architectural Conservation

Lime mortars have a rich history of being blended with organic additives to address weaknesses such as low setting time and hydric properties. This study specifically investigates the impact of incorporating straw and sesame oil into lime mortar mixes, focusing on their influence on open porosity, permeability, water absorption, and durability. While previous studies explored the effects of natural fibers and fatty acid additives on lime mortars separately, this study examines their simultaneous incorporation in mortars. The results demonstrated that the simultaneous addition of sesame oil and straw decreased the water absorption values of the mortars to 77%. Furthermore, the inclusion of sesame oil resulted in a significant 30% increase in impermeability values. However, when both sesame oil and straw were added together, the increase in impermeability was less than 20% compared to the reference mortar with no additives. These findings highlights that the combined addition of sesame oil and straw has a lesser impact on the permeability values of mortars, which is a positive outcome, as maintaining optimal permeability is essential for the long-term preservation of historical substrates. The combination of straw and sesame oil enhances hydric properties without undermining the mortar's structure and permeability. These results emphasize the sustainable nature of lime mortars in restoration projects, showcasing their compatibility with traditional masonry practices. By combining natural fibers with fatty acids, mortars demonstrate improved durability, offering a promising avenue for enhancing performance while retaining essential properties.