(A) use

In stone, the strength, hardness, wear resistance, corrosion resistance of granite is obviously higher than that of marble, so its application is more extensive. In addition, the granite color is generally more uniform, suitable for large-scale decorative buildings.

China in the 20th century since the 1980s with the universal use of diamond processing tools, granite processing from the difficult, yield, the amount of rapid growth, to the national granite production in 1995, the amount of marble is 1 times, in the building materials exports Has become the most foreign exchange of goods. With the development of the economy, the application of granite has been expanding, granite decorative plate large quantities into the building decoration industry, not only for luxury public buildings, but also into the home decoration. The main use of granite is shown in Table 4.24.5.

Table 4.24.5 Main uses of granite

(2) Industrial technical requirements

The industrial requirements for granite vary depending on the application.

1. The main requirements for natural granite blocks

Building materials industry standard (JC-204-92) on the natural granite blocks of the main requirements are as follows:

The blocks must have a rectangular parallelepiped shape. The large surface of the block should be parallel to the joint surface or pattern of the rock.

The size of the block requires a length greater than or equal to 140cm, width greater than or equal to 60cm, height greater than or equal to 60cm.

Appearance quality requirements of the same batch of blocks of color, pattern, grain structure should be basically the same. The quality requirements of the missing angle, missing edge, crack, color line and stain shall be in accordance with Table 4.24.6.

Physical properties: density of not less than 2.50g / cm3; water absorption of not more than 1.0%; dry compressive strength of not less than 60.0MPa; bending strength of not less than 8.0MPa.

Table 4.24.6 Quality requirements for granite blocks

2. The quality requirements for acid and alkali-resistant granite

(1) the quality requirements of acid-resistant granite main chemical composition requirements: SiO2> 70% ~ 75%, the higher the acid content of the better; Al2O3> 13% ~ 15%; Fe2O3 <0.5%; CaO <0.8%; MgO <0.4 %; Acid resistance greater than 97.5%. hard. Thermal resistance (after 10 ~ 40 times the thermal change after the compressive strength) is greater than 16.2MPa, melting point 1610 ℃, expansion coefficient of less than 8 ×10-3, water absorption of less than 1.5%.

(2) the quality requirements of alkali-resistant granite CaO, MgO content is high, the higher the content of alkali resistance is better, some acid-resistant stone SiO2 content is high, but the porosity is small, can also be used as alkali-resistant stone. The chemical composition of alkali-resistant granite produced by Qingdao Material Factory is as follows: SiO276.6%, Al2O314.39%, (K2O + Na2O) 9.07%, Fe2O31.14%, CaO1.34% and MgO0.68%.