Monday, September 28, 2009

Chemical & Physical Properties of Granite

Chemical Properties

Granite is mainly composed of feldspar, quartz along with different other minerals in varying percentage, which are affirmed as follows:

Nominal chemical composition of a variety of oxides

Silica (SiO2) ---------------------- 70-77%
Alumina (Al2O3) ----------------- 11- 14%
Soda (Na2O) ------------------------ 3 – 5%
Potassium Oxide (P2O5) --------- 3 – 5%
Iron (FeO) ----------------------------- 1 – 3%
Iron (Fe2O3) -------------------------- 1-2%
Lime ----------------------------------- 1%
Magnesia (Mg0) ------------------------- .5 – 1%
Titina ---------------------------------- Less than 1 %( .38%)
Water (H2O) --------------------------- 0.03%

Physical Properties

In terms of granites physical properties, it is a unique material. These properties lend uniqueness to granite are:

Co-efficient of expansion :
The co-efficient of expansion for granite vary from 4.7x10-6 – 9.0x10-6(inches x inches).

Porosity/permeability :
Granite has almost negligible porosity range among 0.2 to 4%.

Variegation :
Granite shows constancy in color and texture.

Thermal Stability :
Granite is highly steady thermally, therefore shows no change with the change in temperature. It is impervious to weather from temperature and even from the air borne chemicals. Granite is the high confrontation to chemical erosion that makes it useful for making tanks to store highly caustic material.

Hardness :
It is the hardest building stone and hardness of it that lends it excellent wear.

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