Quick Answer
Lime mortar is generally considered stronger and more durable than cement mortar due to its better bonding properties and ability to withstand stress and movement without cracking.
Composition and Properties
Lime mortar is composed of lime putty, sand, and water. The lime putty is made from high-calcium lime that has been slaked to create a hydraulic binding agent. This lime has a higher pH level than cement, which allows it to bond with the sand particles more effectively, creating a stronger and more flexible mortar. A general mix ratio for lime mortar is 1 part lime to 3 parts sand.
Advantages Over Cement Mortar
Cement mortar, on the other hand, is composed of cement, sand, and water. However, cement has a lower pH level than lime, which can lead to a weaker bond between the cement and sand. This can result in a mortar that is more prone to cracking and degradation over time. Additionally, cement mortar can be more susceptible to damage from freeze-thaw cycles and other environmental stressors. A general mix ratio for cement mortar is 1 part cement to 3 parts sand.
Techniques for Working with Lime Mortar
To work effectively with lime mortar, it’s essential to mix the ingredients correctly and apply the mortar correctly. A mix ratio of 1:3 by volume is a good starting point, but the exact ratio may vary depending on the specific application and desired properties. It’s also crucial to apply the mortar in thin layers and to use a consistent, smooth motion to ensure even distribution and prevent air pockets from forming. In addition, lime mortar should be allowed to set and harden slowly, ideally over a period of several hours or overnight, to achieve optimal strength and durability.
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