Plasticity and Workability: Lime makes mortar more plastic (able to be molded and shaped) and workable. It increases the mortar's ability to be spread and manipulated during application. This enhanced workability allows masons to create smoother and more even mortar joints.
Better Bonding: Lime can improve the bond between mortar and masonry units. It enhances the adhesion of the mortar to the bricks, blocks, or stones, resulting in stronger and more durable joints. Lime also helps reduce the risk of cracking and separation at the joints.
Reduced Shrinkage: Lime can mitigate the shrinkage of mortar as it cures. Shrinkage can lead to cracks in the mortar joints, compromising the structural integrity and weatherproofing of the masonry. Lime helps control and reduce shrinkage, resulting in more stable and resilient mortar joints.
Improved Workability in Cold Weather: Lime is particularly useful in cold weather construction. It can enhance the workability of mortar when temperatures are low, making it easier for masons to work with the material even in adverse weather conditions.
Self-Healing Properties: Mortar containing lime can exhibit self-healing properties to some extent. Over time, lime in the mortar can rehydrate and help seal small cracks or gaps that may develop in the mortar joints, further enhancing the durability of the masonry.
Enhanced Durability: Lime can contribute to the long-term durability of masonry structures. It helps protect against weathering, freeze-thaw cycles, and the effects of moisture infiltration, which can extend the lifespan of the mortar and masonry.
Aesthetics: Lime can improve the appearance of mortar joints by producing a more consistent, creamy color. This can be desirable for architectural or historical preservation projects where aesthetics are a consideration.
There are different types of lime used in mortar, including hydrated lime (Type S) and hydraulic lime (Type N), each with varying properties and characteristics. The choice of lime type depends on the specific requirements of the construction project.
In summary, lime is added to mortar to enhance its workability, bonding strength, resistance to shrinkage and cracking, and overall durability. The use of lime in mortar is a traditional and effective practice that has been used in masonry construction for centuries.
