1. Peeling Treatment. The surface of standard extruded boards is smooth, which can lead to weak adhesion with both adhesive and plaster. To address this, a peeling treatment is applied. This process enhances the bonding surface, ensuring a more uniform and effective adhesion. As a result, the tensile bond strength, water resistance, and freeze-thaw resistance of the system exceed 0.25 MPa, significantly improving the overall adhesion and reliability of the insulation system. Additionally, the peeling treatment helps to evenly release internal stresses, reducing the risk of cracking or delamination over time.
2. National Standards. Currently, there is no national standard specifically for extruded boards in construction applications. As a result, many projects have relied on the technical standards originally designed for expanded polystyrene (EPS) boards. In June 2009, the Shanghai Academy of Sciences and the National Building Standard Design Institute collaborated to develop technical guidelines for the use of extruded boards in exterior wall insulation systems. Around the same time, the national standard 08CJ16, titled "Extrusion Plate Insulation System Building Structure," prepared by Knauf, was also revised at the National Building Standard Design Institute. Industry efforts continue to improve the application specifications and standards for extruded boards, ensuring their safe and efficient use in external insulation projects.
The national standard specifies that the dimensional stability of peeled extruded boards must be ≤2.0%. Knauf has conducted research in this area, proposing the installation of expansion joints in specific regions of the external thermal insulation system. This allows the system to effectively manage and release internal deformations, preventing structural issues caused by temperature and weather changes.
3. Dimensional Stability. In the industry, it is commonly believed that extruded boards may experience deformation due to poor dimensional stability, especially under weather conditions, potentially leading to cracks in the finish layer. However, when comparing the elastic modulus of the materials used in the system—mortar at around 15,500 MPa, EPS at 4–6 MPa, and XPS at 7–9 MPa—it becomes clear that both EPS and XPS are in the same order of magnitude compared to mortar. Therefore, the constraints imposed on the materials remain largely unchanged. There is no substantial evidence suggesting that mortar is more constrained by EPS than by XPS. Many real-world projects have confirmed that both systems perform well in practice, and the difference in elastic modulus does not significantly impact long-term performance.
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