Why are more and more buildings now using aluminum composite panels?

Advantages of curtain walls

1. Lightweight Compared with the same area, the weight of a glass curtain wall is about 1/10 to 1/12 that of a painted brick wall, 1/15 that of a marble or granite wet-process wall, and 1/5 to 1/7 that of a concrete hanging plate. In general buildings, the weight of the inner and outer walls accounts for about 1/4 to 1/5 of the total weight of the building. The use of curtain walls can greatly reduce the weight of the building, thereby reducing the cost of foundation engineering.

What is a curtain wall?

Curtain walls are exterior building enclosures that do not bear weight. They are hung like curtains, hence the name "curtain wall." They are lightweight walls with decorative effects commonly used in modern large and high-rise buildings. Composed of panels and a supporting structural system, they can have a certain degree of displacement relative to the main structure or have a certain degree of deformation themselves. They are exterior building enclosures or decorative structures (exterior wall frame support systems are also a type of curtain wall system) that do not bear the loads of the main structure.

Performance comparison of aluminum plate curtain walls

Material Composite aluminum panel - Two 0.5mm thick pure aluminum plates are sandwiched between PVC or PEC plastic and roll-pressed and thermally bonded. Aluminum alloy single plate - 2~3mm aluminum alloy plate.

Characteristics of aluminum plate curtain walls

1. Aluminum plate curtain walls are rigid, lightweight, and high-strength. Aluminum single-plate curtain walls have good corrosion resistance, and the fluorocarbon paint can last for 25 years without fading. 2. Aluminum plate curtain walls have good processability. Using a pre-processing and post-painting process, aluminum plates can be processed into various complex geometric shapes such as planes, arcs, and spheres. 3. Aluminum plate curtain walls are not easily stained and are easy to clean and maintain. The non-adhesive nature of the fluorocarbon coating film makes it difficult for pollutants to adhere to the surface, and it has better cleanability. 4. Aluminum plate curtain walls are convenient and quick to install and construct. Aluminum plates are formed in the factory, and no cutting is required on-site; only simple fixing is needed. 5. Aluminum plate curtain walls can be recycled and reused, which is environmentally friendly. Aluminum plates can be 100% recycled, and their recycling value is higher. Aluminum plate curtain walls have a unique texture, rich and lasting colors, and a variety of appearances. They can be perfectly combined with glass curtain wall materials and stone curtain wall materials. Their perfect appearance and excellent quality make them favored by owners. Their light weight, only one-fifth that of marble and one-third that of glass curtain walls, greatly reduces the load on the building structure and foundation, and their maintenance cost is low, and the performance-to-price ratio is high. For the aluminum plate curtain walls currently used in China, the vast majority are composite aluminum plates and aluminum alloy single plates. Composite aluminum plates consist of two outer layers of 0.5mm pure aluminum plates (0.2～0.25mm for indoor use) with a 3～4mm thick polyethylene (PE or polyvinyl chloride PVC) layer in between, which are roll-pressed and thermally bonded. The product is a flat plate of a certain specification, such as 1220mm×2440mm. The fluorocarbon paint on the surface of the exterior composite aluminum plate is also roll-coated, roll-pressed, and thermally bonded at the same time. The thickness of the coating is generally around 20μm. The advantages of composite aluminum plates are their light weight, smooth surface, good flatness, no color difference in the same direction, and excellent on-site processability. They provide conditions for handling changes in the exterior wall dimensions caused by on-site construction errors, reducing the workshop processing cycle and shortening the installation period. When installing the composite aluminum plates, they need to be processed into wall panels. First, the plates need to be cut according to the dimensions of the secondary design. When cutting the plates, the size of the folded edges needs to be considered. Generally, about 30mm is added to each side. According to curtain wall installation companies, the yield rate of cutting plates is generally 60%～70%. The cut composite plates need to have grooves cut on all four sides, that is, a certain width of the inner aluminum plate and plastic layer is cut off, leaving only the 0.5mm thick outer aluminum plate. Then, the edges are folded into 90-degree right angles. Then, a sub-frame of the same size is made using aluminum profiles and placed in the groove of the bent aluminum-plastic plate. The bottom surface of the sub-frame is bonded to the back of the aluminum-plastic plate with structural adhesive, and the four folded sides are fixed to the outside of the sub-frame using rivets. The sub-frame usually also has reinforcing ribs to ensure the mechanical strength of the wall panel. The reinforcing ribs are made of aluminum and bonded with structural adhesive. Some non-standard methods only fix the corner aluminum at the four corners of the composite plate, and the reinforcing ribs are bonded with double-sided tape, which greatly reduces the firmness. Aluminum alloy single plates are generally 2～4mm aluminum alloy plates. When making them into wall panels, they are first subjected to sheet metal processing according to the requirements of the secondary design, directly folded, and the four corners are high-pressure welded into a tightly sealed groove. The back of the wall panel uses electric welding studs to pre-leave the fixing bolts for the reinforcing ribs. After the sheet metal work is completed, fluorocarbon paint is sprayed, generally with two coats and three coats, and the paint film thickness is 30～40μm. Aluminum alloy single plates are easy to process into arcs and multiple folded edges or sharp angles, and can meet the needs of ever-changing exterior wall decoration today. They also have rich colors and can be selected according to the design and owner's requirements, truly expanding the design space for architects.

Surface treatment of aluminum panel curtain walls

Aluminum plate curtain walls are generally pre-treated with chromatization and other processes before being fluorocarbon coated. The fluorocarbon coating uses polyvinylidene fluoride resin (KANAR500) for both the topcoat and clear coat. Generally, this involves two, three, or four coats. The fluorocarbon coating has excellent corrosion resistance and weather resistance, resisting acid rain, salt spray, and various air pollutants. It has excellent resistance to hot and cold temperatures, can withstand strong ultraviolet radiation, and can maintain its color and prevent powdering for a long time, resulting in a long service life.