Wide application of non-porous granite stone wall with caution

granite stone wall of non-widely used in Europe, has a long history; North America, high-rise buildings, the use of limestone, marble plate quite a bit, a lot of height but also more than 200m. In recent years, a number of projects, architects require the use of non-granite stone to meet the architectural requirements, such as Shenzhen Cultural Center (tuff), Dongguan City Administration Building (yellow brown sandstone), Bank of China head office in Beijing (yellow gray marble rock), Guangzhou, Guangdong Development Building (green sandstone), Beijing Financial Street buildings (m yellow sandstone), Mirage Tower (beige travertine) and so on.

As the current specification for the building of such stone wall is not provided, so each country carried out the above works are experts, put forward the corresponding technical measures.

(A) Type of stone

Non granite stone, should give priority to igneous rocks; can be used sandstone, marble; really necessary, they can considering the selection of limestone; with loose and porous stone, the wish to take it seriously.

In general, silicon dioxide (SiO2) content of the stone, has high strength and durability, including silicon dioxide (SiO2) 50% or more of the stone, suitable for external walls. On the contrary, calcium oxide (CaO) content of the stone susceptible to atmospheric corrosion of sulfur dioxide and other gases, such stone for the walls, to a more perfect surface treatment, more effective anti-corrosion measures.

(B) the density and uniformity

1. The same type of stone, bulk density has a certain range. Usually a large stone bulk density, material density, high strength and good durability. Bulk density is lower than 2.1g/cm3 ρG stone for the low-density; ρG = 2.1g/cm3 ~ 2.5g/cm3 to medium density; ρG ≥ 2.5g/cm3 high density. Stone for the walls, the density should be consistent with the requirements of Table 1.

2. For curtain wall of stone, should be more uniform texture.

(1) There should be soft stone sandwich or weak veins.

(2) the pattern of the rock layer, not a coarse, loose, porous stripes.

(3) the pore size of porous rock should not be too large, the holes too deep. The number of holes should not be too much. Otherwise, measures should be taken to seal the hole.

(C) the strength of stone

As an important indicator of the strength of stone for the dry state

Igneous rocks (including granite) fm average bending strength test of not less than 10N/mm2, when the bending strength of specimens in less than 8 N/mm2, the batch of stone walls should not be used; other stone should not be less than fm 4 N/mm2, when the bending strength of specimens in less than 3 N/mm2, the batch of stone walls should not be applied.

Strength of the direction of sedimentary rock is sometimes inconsistent, then the force along the main direction of the stone panel strength should be consistent with the above requirements.

(D) freezing and thawing factor

After freeze-thaw cycles stone, strength decreased. Granite freeze-thaw cycle test carried out according to national standards GB9966.2. Strength after freezing and thawing and the original strength coefficient ratio as freezing and thawing. Stone for the walls, the freezing and thawing factor should not be less than 0.8.

(E) water absorption: the stone for the walls, the water absorption should not exceed the limits in Table 2.

(F) Radioactive: stone for the walls, the radiation should follow the "building materials radionuclide limited" GB6566 in the A-, B-class stone requirements.