With the increase in population and the reduction in land use, there are more and more high-rise buildings. High-rise buildings cannot do without towering curtain walls. Over time, if they are not maintained, the curtain walls will become extremely ugly. The cause of this phenomenon is the accumulated pollution. Stone pollution is generally caused by the design and construction stages, not overnight. If the design plan is unreasonable and the construction method is wrong, it is an important factor causing stone pollution.
01: Wrong drainage direction
In the same building, some directions are particularly polluted, while some locations are not so obviously polluted. Under the same material conditions, the location with serious pollution must be that the drainage direction was not effectively controlled during the design, resulting in the formation of an inclined surface of water flow in some locations, while some locations can be reasonably drained.
the stone on the left platform is almost as bright as new, while the stone under the railing on the right is more seriously polluted.
We conducted research and found that the high platform adopts a 3% drainage slope design, so that the top water is discharged inward, while the low position adopts a free drainage method outward. When the water flows, it drives some dust, and the dust adheres to the surface of the stone, which easily forms water marks.
02: Irrational drainage pipe design
As a functional existence, the drainage pipes of many buildings are often exposed on the outer surface of the building, and some high-end villas often set the drainage pipes inside the curtain wall in order to preserve the integrity of their facades. If there is water leakage in the drainage pipe, it is difficult to check it in the first time, and it is often not discovered until the water seeps out of the stone panel.
Due to the hidden design of the drainage pipe, it is difficult to repair, and the stone needs to be disassembled to achieve it, which is also secondary damage to the stone curtain wall itself. Moreover, the strength and appearance of the stone curtain wall are seriously affected after long-term washing with sewage.
03: Inappropriate surface material selection
Inappropriate surface material selection
In the selection of panels for stone curtain walls, it is necessary to pay attention to the fact that many are only suitable for indoor use, such as marble. Due to its poor durability, corrosion resistance and weathering resistance, it cannot be used for a long time in the changing natural environment outdoors. Generally, granite and sandstone are used outdoors. For sandstone, in fact, in addition to considering its safety, its self-cleaning ability must also be considered.
As shown in the figure below, the surface porosity of sandstone is relatively high, and these holes provide space for the growth of mold. Usually, some sandstone decorations often have black spots on the surface that are difficult to clean, and some low-rise buildings even have green moss attached to the surface, which greatly interferes with the cleaning work.
04: Incorrect installation of thermal insulation materials
When stone curtain walls are installed, they are often filled with thermal insulation materials. Generally, thermal insulation cotton is used. The outer surface of the thermal insulation cotton has a layer of aluminum foil to isolate moisture and keep the thermal insulation cotton dry. However, many construction unit staff do not understand its purpose and simply think that it is just packaging. It is common to tear it up during the construction process.
What is more serious is that once the rainy season comes, the insulation cotton will fully absorb water and its weight will increase. After the insulation cotton absorbs water and droops, the waste cotton with high water absorption rate will accumulate at the bottom, close to the stone panel and the connector, which will not only easily oxidize the metal connector but also cause its water to seep out from the pores of the stone, forming uneven water spots, which is extremely unsightly from the facade.
05: Unqualified transfer hangers
The curtain wall structure needs to be connected with stainless steel or aluminum alloy. For cost considerations, stainless steel is more widely used. Some construction companies also cut corners and use inferior stainless steel. In the early stage of the construction, the impact is not great, but as the years of use increase, the galvanized layer on the metal surface is worn, and iron oxide is formed under the oxidation of water. Rust is easy to penetrate through the connection parts, resulting in rust marks on the panel.
06: Unqualified stone sealant
The sealant has the greatest impact on the pollution of the panel. Due to the characteristics of its material, the erosion penetrates from the edge to the inside. Therefore, no matter whether it is mechanical cleaning, physical cleaning or chemical cleaning, it cannot be effectively cleaned. Therefore, the sealant must be carefully selected.
During the construction process, the sealant used must be tested for oil penetration. Only pollution-free sealants can be used. Inferior glue mixed with white oil (mineral oil) must not be used for stone curtain wall grouting to avoid oily substances from penetrating into the edge of the stone, forming a special pollution shape with the glue joint as the center and spreading to both sides.
Stone is a microporous material. If it encounters external pollution, it will penetrate deep. Oil pollution is the most common and most serious pollution. It can only be disassembled and replaced once it has been installed in the curtain wall; it cannot be cleaned.