The treatment of expansion joints in aluminum curtain walls is crucial for ensuring structural safety and aesthetic integrity under temperature changes, foundation settlement, or seismic forces. The core technique lies in constructing a flexible connection system that adapts to deformation needs through scientific design, precise construction, and appropriate material selection, while simultaneously considering waterproofing, fireproofing, and decorative functions.
The classification of expansion joints depends on the type of deformation. Aluminum curtain wall expansion joints are mainly divided into three categories: expansion joints, settlement joints, and seismic joints. Expansion joints address the expansion and contraction of materials caused by temperature changes, releasing stress through pre-reserved gaps to prevent cracking of the curtain wall panels. Settlement joints are used to cope with uneven building settlement, preventing damage from compression between adjacent structures. Seismic joints address seismic forces by dividing the curtain wall into independent units, reducing the transmission of seismic energy. During the design phase, the type and location of expansion joints must be comprehensively determined based on the climate conditions, geological characteristics, and seismic fortification requirements of the building's location. For example, in northern regions with large temperature differences, the spacing of expansion joints needs to be appropriately reduced; in areas with soft soil foundations, settlement joints must run through the entire height of the curtain wall to ensure independent settlement of each part.
The design of expansion joints must balance functionality and aesthetics. Aluminum curtain wall expansion joints typically consist of an aluminum alloy base, a waterstop, cover plates, and sliding rods. The base is fixed to the main structure, providing stable support for the expansion joint; the waterstop, made of rubber or silicone, prevents rainwater penetration through elastic deformation; the cover plates cover the surface of the expansion joint, protecting the internal components and maintaining the smooth appearance of the curtain wall; the sliding rods connect the cover plates on both sides, allowing them to slide freely with structural deformation. The design must ensure material compatibility among components to avoid affecting service life due to electrochemical corrosion. For example, when using an aluminum alloy base with stainless steel sliding rods, insulating gaskets must be used to prevent contact corrosion.
Construction and installation must strictly follow the process flow. First, expansion joint grooves must be pre-reserved according to design requirements, ensuring accurate groove dimensions and smooth edges to avoid installation difficulties due to groove deviations. Second, when installing the aluminum alloy base, expansion bolts or welding must be used for fixation to ensure a firm connection between the base and the main structure. Next, lay the waterstop, ensuring that the joints are joined using overlapping adhesive and that the joint length meets sealing requirements to prevent rainwater seepage. Then, install the sliding rods and cover plates. The sliding rods must be level, and the cover plates must be flush with the curtain wall surface to avoid unevenness affecting the appearance. Finally, check the installation quality of each component of the expansion joint to ensure smooth sliding of the sliding rods, secure fixing of the cover plates, and tight sealing of the waterstop.
The waterproofing of the expansion joint requires multiple lines of defense. In addition to the waterstop, waterproof sealant can be filled inside the expansion joint to form the first line of defense. At the junction of the cover plate and the curtain wall, weather-resistant sealant is used to caulking the joint to prevent rainwater from seeping in. For external wall expansion joints, drainage channels can be installed under the cover plates to guide seeping water outdoors, preventing water accumulation and erosion of the curtain wall. The waterproofing material must be a silicone-based sealant compatible with the aluminum curtain wall to ensure long-term use without aging or cracking.
The fireproofing of the expansion joint must comply with fire safety regulations. Fire-resistant rock wool or aluminum silicate fiber tape is filled inside the expansion joint to prevent the spread of fire. Fire-resistant sealant is used at the junction of the cover plate and the curtain wall to improve fire resistance. Fire-resistant materials must have a fire resistance limit test report to ensure effective fire suppression in the event of a fire.
Regular inspection is necessary for the maintenance of expansion joints. Regularly clean debris and dust from inside the expansion joint to prevent blockages that could affect its deformation function; check the aging of the waterstop and sealant, and replace damaged components promptly; check the sliding performance of the sliding rods to ensure the cover plate can move freely with structural deformation. Regular maintenance extends the service life of the expansion joints and ensures the long-term safe use of the curtain wall.
The treatment of expansion joints in aluminum curtain walls requires comprehensive consideration from design, construction, waterproofing, fireproofing, and maintenance. Through scientific material selection, precise construction, and regular maintenance, a flexible connection system that adapts to deformation needs is constructed, providing reliable safety and a lasting decorative effect for the curtain wall.
