External wall aluminum plastic panels, widely used in modern architecture, directly impact the safety, durability, and aesthetics of buildings through the quality of their joint treatment. Failure to strictly adhere to specifications during construction can lead to a chain reaction of problems, escalating from localized defects to systemic risks.
The most obvious consequence of improper joint treatment is water seepage. If sealant is not used at the joints of aluminum plastic panels, or if the sealant is not properly applied, rainwater will seep into the wall structure. Long-term seepage can cause the base material to warp due to moisture absorption; for example, the expansion of plywood due to moisture absorption can cause bulging on the surface of the aluminum plastic panel, and even lead to panel detachment. In humid southern regions, water seepage can also accelerate the embrittlement of the plastic core layer, causing fading, cracking, and other signs of aging within 5-8 years. If water seepage spreads into the interior, it can damage the structural integrity of the building, leading to secondary disasters such as mold growth on walls and short circuits.
Defective joint treatment significantly weakens the wind pressure resistance of aluminum plastic panels. External wall aluminum plastic panels are spliced together to form a unified curtain wall, and the connection strength at the joints directly affects wind resistance. If specialized structural adhesives or rivets are not used for fixing, or if the spacing between fixing points is too large, relative displacement can easily occur between the panels under strong winds, leading to cracks at the joints. In northern regions with large temperature differences, the internal stress caused by the difference in the coefficients of thermal expansion between the aluminum layer and the plastic core layer (aluminum is 23.6×10⁻⁶/℃, plastic is 100×10⁻⁶/℃) will further exacerbate joint damage. This structural damage not only affects the building's appearance but may also pose a risk of falling objects from heights, threatening pedestrian safety.
Improper joint treatment can also accelerate the aging process of aluminum composite panels. Unsealed gaps become channels for dust and acidic/alkaline substances to enter, which corrode the surface coating of the aluminum panel, damaging its weather resistance. For example, when wiping with acidic or alkaline cleaning agents, if the gaps are not sealed, corrosive substances will directly contact the aluminum panel, forming irreversible scratches and color differences. In addition, ultraviolet rays can directly penetrate the plastic core layer through the gaps, accelerating its photo-oxidation reaction, causing the core layer to become brittle and lose toughness, ultimately leading to cracking of the panel. The effects of thermal expansion and contraction are amplified by defects in joint treatment. Aluminum composite panels (ACPs) expand and contract under diurnal temperature variations. If insufficient expansion space is provided at the joints or if elastic sealing materials are not used, unevenness will occur due to mutual compression between the panels. This deformation is particularly pronounced in cold northern regions, leading to widespread cracking and panel detachment at the joints after 10 years. Long-term temperature fluctuations can also cause internal stress accumulation, resulting in bulging, warping, and compromised overall flatness.
Improper joint treatment can also lead to decreased sound and heat insulation performance. The plastic core layer in the middle of the ACP is only 2-5mm thick, and its sound insulation effect depends on the sealing between the panels. If the gaps are not effectively treated, external noise will enter the room through them, reducing living comfort. In terms of heat insulation, air seeping into the gaps forms thermal bridges, accelerating heat loss and easily causing condensation and mold growth on walls in summer. This performance degradation indirectly increases building energy consumption, which is inconsistent with the trend of green building development.
From a construction process perspective, improper joint treatment often stems from non-standard operations. Some construction teams, in an effort to save costs, use inferior sealants or reduce the number of fasteners, resulting in weak adhesion between the panels and the substrate. For example, using quick-drying adhesive instead of silicone sealant can lead to delamination due to insufficient weather resistance and seasonal temperature changes. Furthermore, failure to clean the joint surface before applying sealant can leave residual water stains and dust, weakening the seal and even causing the sealant layer to crack.
The treatment of joints in external wall aluminum plastic panels is a crucial aspect of ensuring building quality. From potential water seepage to structural safety, from accelerated aging to performance degradation, every detail affects the building's lifespan and user experience. Only by strictly adhering to construction specifications, selecting high-quality materials, and strengthening process supervision can the risks of improper joint treatment be minimized, ensuring the long-term stable function of the aluminum plastic panel curtain wall.
