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ITS ORIGINS
Under the generic name of granite we can include a group of crystalline rocks whose formation is due to a very slow cooling of the liquid magma from the Earth’s core.
The genesis of these rocks itself gives these materials exceptional qualities not only from the aesthetic point of view but also technologically speaking.
ITS COMPOSITION
Grained rocks are formed of a wide range of different type of minerals.
Under the trade name of granite a great variety of rocks is included. And they have specific petrographic names depending on the percentage and characteristics of the minerals they are composed of. The most common ones are: granite, syenite, quartz diorite, gabbro, etc.
ITS CHARACTERISTICS
Physical Characteristics
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Densidade aparente: |
granite apparent density is very variable depending on the type of granite. Values higher than 2.6 t/m3 are normally achieved, and the so-called black granites are the type with the highest density. This values show that granite is an exceptional building material. |
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Water absorption at atmospheric pressure:
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water absorption of granites is quite low, with values that are usually under 0.6%, which means that granite has a good performance against ice and a low cost of maintenance. |
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Behavior against ice: |
in accordance with its physical characteristics, granites tend to behave well against frost, even in areas with extreme weather conditions. |
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Mechanical Characteristics
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Resistance to compression: |
granites are rocks which resist compression efforts very well, with a much higher compression strength than that of the concrete.
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Resistance to flexion: |
today, granite flexion resistance makes it possible to build very thin pieces to be used in different applications such as pavements, flooring tiles, lintels, etc. |
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Impact resistance: |
granite has a quite high impact resistance, thus it is very appropriate to be used in pavements or baseboards where the risk of impact is high. |
Building characteristics
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Erosion resistance: |
granites resistance to erosion is the capacity of not losing mass with friction. In comparison with other ornamental stones, granite has a high erosion resistance due to its quartz content. |
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Workability: |
workability is the capacity of a stone to take the desired shape, dimension and surface finish. Due to the homogeneity of its crystalline structure, granite can take any shape in a wide range of sizes. |
EXTRACTION
Traditionally, granite is quarried from open-air quarries and using diamond wire sawing, ranging shearers and circular saws. This requires the building of several levels and.
Granite quality control starts in the quarry.
On average, a 25% of the extracted granite is commercialized in block shape. Pieces with any kind of impurity are set aside fro a second quality control. Those blocks with a slight flow due to chipping or cracking are cut to obtain bondstones, curbs or paving stones. |
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