Hydraulic Lime - Use in Construction

Use in Construction

Hydraulic lime is a useful building material for the following reasons:

• It has a low elastic modulus.
• There is no need for expansion (movement) joints.
• It allows buildings to "breathe", and does not trap moisture in the walls.
• It has a lower firing temperature than Portland cement, and is thus less polluting.
• Stone and brickwork bonded with lime is easier to re-use.
• Lime acts sacrificially in that it is weaker and breaks down more readily than the masonry, thus saving weaker stone such as sandstone and limestone from the harmful effects of temperature expansion and mortar freeze.
• It is less dense than cement, thus less cold bridging.
• Lime re-absorbs the carbon dioxide (CO₂) emitted by its calcination (firing), thus partially offsetting the large amount emitted during its manufacture. The more hydraulic a lime, the less CO₂ is reabsorbed during set, for example, 50% of CO₂ is reabsorbed by NHL 3.5 during the set, compared to 100% of CO₂ being reabsorbed by pure calcium hydroxide (fat lime putty).