Limecrete

Limecrete is a combination of natural hydraulic lime and lightweight aggregate such as sharp sand or glass fibres. This creates a breathable material which can be used as an alternative to concrete, in particular for floor slabs in the conversion of old buildings to modern standards - helping to deal with naturally occurring moisture. Limecrete can help to resolve design problems associated with older buildings and energy efficiency, while retaining a traditional character and aesthetic.

It is a 'breathable' material, which allows the transmission of water vapour. When used as a floor slab, this can help ensure that any rising damp does not affect breathable wall constructions.

Limecrete is often laid on a base of foamed glass beads rather than hardcore, without a damp proof membrane (DPM). This enhances the breathability of the slab, since hardcore can allow capillary action to draw up ground moisture. Foamed glass beads are the most common option since there are few other non-capillary substrate materials available.

Limecrete is relatively slow to set and absorbes CO2 during the drying process. It has a certain amount of flexibility compared to concrete. It is strong enough under compression to serve as a floor slab material, and can be strengthened by adding fibres and increasing the lime content. Care should be taken in mixing the materials however as excessive lime content can compromise breathability.

Underfloor heating can be used with limecrete.

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[edit] Related articles on Designing Buildings Wiki

• Concrete.
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• Rising damp.
• Self-compacting concrete.
• The properties of concrete.
• Topmix Permeable.
• Types of floor.
• Understanding dampness.