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發表於 2010-11-25 05:06:54
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1230# Heather
再請教
石灰粉是lime還是chalk?
pearl 發表於 2010-11-24 10:18 
是Hydraulic lime
http://en.wikipedia.org/wiki/Hydraulic_lime
Hydraulic lime is a useful building material for the following reasons:
* It has a low modulus of elasticity.
* 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). |
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