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A Few Advantages of Lime Based Mortar

A Few Advantages of Lime Based Mortar

The core concern in masonry preservation is a commitment to using lime based mortar for all historic structures. Lime based mortar has many advantages over Portland cement. Here is a short list of just a few advantages:


Lime based mortar is more flexible and less brittle.
If there is building movement, lime mortar will eventually re-seal the cracks in the mortar. Having a softer mortar means soft bricks and stones won’t be forced to break. The mortar is the “sacrificial component” of any masonry wall. With Portland, the mortar is so hard that it chisels off the faces of the bricks with even the slightest building movement and all buildings move.


Lime based mortar is breathable.
This means that moisture that gets in the wall (from damp conditions inside or outside) will escape rapidly. Portland cement seals moisture into a wall, causing mold problems inside, deterioration of wood, and deterioration of the bricks or stones themselves.Lime based mortar still sheds water from rain just as well as Portland cement.


Lime mortar lasts longer.
Lime will last longer than Portland cement. Lime mortar that is made from 98% pure calcium will last 100 years minimum. Portland cement mortar lasts about 50 years, and sometimes cracking and deterioration is visible within 10 years. Portland cement degrades from the inside out because of impurities like aluminum silicates. These impurities cause it to get hard fast, but also cause it to deteriorate fast.


Because lime based mortar is softer, it can be removed easily, without damaging the bricks or stones. Portland mortar is so hard that it is very difficult to replace without breaking or de-facing the bricks or stones, even if it is badly deteriorated.