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Safe use: Lime is alkaline like cement, with the same caustic effect on the skin. Cover the skin with damp-resistant fabric, e.g. nitrile gloves, and wear goggles. Avoid inhalation of lime dust.
kellyjones00 (593)
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Non-bearing walls: A low-cost, environmentally friendly technique uses hydrated lime to bind weeds, infilling between wall studs. Instructions:
- Shred weeds (woody twigs, small branches) into 1cm slivers.
- Set up formwork around vertical studs, to pour mix into, of about 50cm in height.
- Pour weed chips into a cement mixer or bathtub. Dampen, mix, then add hydrated lime [a.k.a. slaked lime, Ca(OH)2], sand, and cement. A good recipe by weight: 11kg dried weeds, 20L water, 18kg lime, 17kg clean sand, 1kg cement. Mix thoroughly. It should look and feel like slightly-damp muesli. Make a ball to test cohesion.
- Pour mix between wooden forms. Roughly level the surface, then tamp it lightly flat with a flat board on the end of a long stick. Don't ram, to keep air spaces for insulation. Do 15cm layers for even insulation.
- Formwork can be removed the next day, and placed above the completed section to continue upwards.
- Hydrated lime cures slowly by reaction with CO2 in the air. Keep the wall protected from direct sun, wind and rain for 3-4 weeks. Then use a breathable lime render (not concrete), or clad one side.
kellyjones00 (593)
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Lime binder in earth walls: A small proportion of lime is used to stabilise earth walls. Adobe and rammed earth both are made mostly of sand (~75%) with smaller proportions of clay and hydrated lime. Adobe is poured into brick forms, while rammed earth is poured between forms and tamped to compress hard to half the volume.
kellyjones00 (593)
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Mortar: Hydrated lime is a traditional brick mortar. It takes much longer to cure and deteriorates faster, than cement, but hydraulic limes can be used in walls with exposure to severe weather. Salt water must not be used in mortars.
kellyjones00 (593)
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Render / Plaster: Lime mixed with sand and water creates a white, anti-bacterial surface on internal ("plaster") and external walls ("render"). Multiple thin layers, starting coarse and ending fine and smooth, endure better. Lathe and plaster, and wattle and daub, help the lime mix stick to the wall.
kellyjones00 (593)
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