Lime building material

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The lime used in green building

Keywords: construction, mortar, wall, cement, eco-construction, moisture benefits.

Why use the lime green building?

Lime has the following advantages compared to conventional cements.

  • permeability
  • Lime absorbs little moisture and quickly rejects: it is a "breathable" materials. The main defect walls mounted with cement is the rise of soil moisture by capillary action. The cement being sealed, the moisture can not evaporate and remains in the walls, leading to corrosion and cracking of materials, mold etc. Lime, on the contrary, rid the walls of their moisture, and thus eliminates related problems.

  • plasticity
  • All walls "work": they naturally subside over time, react to changes in terrain and other factors. The plasticity of lime enables it to support these movements by keeping the cohesion of the book, instead of cement which, because of its rigidity, will tend to break down, creating cracks and jeopardizing the strength of the together.

  • Its disinfectant properties
  • Think of "liming" stables: lime limit the proliferation of mites, fungi, saltpetre and odors. It helps to clean up your environment naturally.

  • versatility
  • In construction, lime uses are multiple and especially, it is suitable for almost all types of media, be it straw, stone, clay, rammed earth or other.

  • aesthetics
  • The feeling of softness and well-being that emerges from a lime wall is not to be overlooked. On the other hand, if the lime is mixed with the local sand, it allows seamless integration to the soil and gives an inimitable style to your building.

The principle of obtaining the lime

Lime is obtained by baking limestone around 900 ° C. This calcination removes the carbon dioxide content in limestone and produces what is called the "quicklime". Quicklime is extremely thirsty for water and "burns" all organic body that comes in contact with it by emptying the water it contains. The next step is to "extinguish" quicklime by adding water. If the added amount of water is limited, lime take the form of a very fine powder and if the amount of water is excessive, it will have the consistency of a more or less thick paste.

After implementation, the carbonation process begins. To go fast, mortar moisture captures carbon dioxide from the air and thus lime will gradually recover carbon dioxide that had been taken away during calcination and return to his state limestone. This process can take months.

aerial and hydraulic lime

For the lime cycle described above is perfect, it takes a very pure limestone. In this process, carbon dioxide which allows carbonation comes from the ambient air. Therefore lime outcome of pure limestone (or almost) is called "lime."

However, pure limestone is relatively rare. It usually contains other elements, in particular silica. But this impurity is not a constraint, quite the contrary, since it gives other interesting properties with lime.

Silica combines with the limestone during calcination and gives more resistance mortar. The more silica coating will be more hard and tough but it will also more brittle. Furthermore, the carbonation will more only from the air, but also in the presence of water, which is why some of the lime can be implemented under water. These are hydraulic limes.

Learn more about the lime:
- Forum and HQE green building
- Manual hydraulic natural Lime green building by Olivier Labesse (.pdf Pages 54 and 1.3 MB for members)

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