The curtain wall belongs to the appearance project in the architectural decoration, which plays a role similar to a human face. The style, taste and other factors of the curtain wall design directly affect people's overall perception of the building. Nowadays, in some large and high buildings, villas Buildings are becoming more and more popular. Among them, stone curtain walls are more popular. Then, what kind of stone is usually used for stone curtain walls? Let's take a look with the editor.
freeze-thaw coefficient
The strength of the stone is reduced after the freeze-thaw cycle. The freeze-thaw cycle test of granite is carried out according to the national standard GB9966.2. The ratio of the strength after the freeze-thaw cycle to the original strength is called the freeze-thaw coefficient. The freeze-thaw coefficient of stone used for curtain wall should not be less than 0.8.
Corrosion resistance and durability
Generally speaking, stone with high content of silicon dioxide (SiO2) has higher strength and durability. Stone with more than 50% silicon dioxide (SiO2) is suitable for external curtain wall. On the contrary, stone with high calcium oxide (CaO) content is susceptible to corrosion by gases such as sulfur dioxide in the atmosphere. Such stone is used for curtain walls and requires more perfect surface treatment and more effective anti-corrosion measures.
water absorption
The water absorption rate of stone should be less than 0.8%
density and uniformity
1. The same type of stone has a certain distribution range of bulk density. Generally, stone with high bulk density has dense material, high strength and good durability. Stone with bulk density ρG lower than 2.1g/cm3 is low density; ρG=2.1g/cm3～2.5g/cm3 is medium density; ρG≥2.5g/cm3 is high density. The density of the stone used for the curtain wall should meet the requirements of Table 1.
2. The stone used for the curtain wall should have a uniform texture.
(1) There should be no weak interlayer or weak veins in the stone.
(2) Rocks with layered patterns should not have coarse, loose and porous stripes.
(3) Porous rocks should not be too large or too deep. The number of holes should not be too much. Otherwise, sealing measures should be taken.
radioactivity
The radioactivity of the stone used in the curtain wall shall meet the requirements of the A and B stone in the "Limits of Radionuclide for Building Materials" GB6566
High strength
As an important indicator of stone strength, it is dry.
The average value fm of the bending strength test of igneous rock (including granite) should not be less than 10N/mm2. When the bending strength of the specimen is lower than 8 N/mm2, the batch of stones should not be used in the curtain wall; the fm of other stones should not be less than 4 N/mm2, when the bending strength of the test piece is lower than 3 N/mm2, this batch of stone should not be used in the curtain wall.
Sedimentary rocks sometimes have inconsistent strengths in various directions. At this time, the strength along the main force direction of the stone panel should meet the above requirements.