At present, the main way to deal with the problem of cracking is: Baotou GRC Material performance, installation and structure of components.
To improve the material performance of components, there are two main goals: first, reduce the shrinkage value of components, including dry shrinkage value and cold shrinkage value, to reduce the shrinkage deformation of components; The second is to improve the elasticity of components and joint materials and increase the tensile deformation value. Through this "one increase and one decrease", we can achieve the balance between the shrinkage deformation and tensile deformation of the component as much as possible. However, at present GRC The characteristics of lightweight components make it difficult to balance the tensile and shrinkage values.
In terms of the installation structure of components, the current main direction is generally on the joint treatment and joint materials of components.
On the premise that the quality of the component itself is qualified, the interface of the component is always weak, and it is easy to generate gaps. It is more difficult to simply use the "bonding" method to prevent gaps. Even if the glass fiber cloth is pasted on the interface of the component, it is difficult to solve this problem. The component will shrink, and it is difficult to pull through tension. As a result, the component cracks or component cracks often occur, because the balance between shrinkage deformation and tensile deformation has not been solved. In addition, the installation of components requires up and down, repeated wrong alignment, which makes it difficult to achieve full mortar. Most of them are filled with mortar after installation, which makes it difficult to ensure the viscosity.
It is correct to use elastic mortar to increase the tensile deformation value to avoid cracking of member joints. However, in practice, there is a difference that is difficult to solve, that is, the contradiction between the high elasticity of elastic mortar and the low elasticity of component finishing materials. The tensile ratio of component facing materials (such as putty) is far less than that of elastic mortar, and the component surface will still crack. If the finish material is required to reach the same high tensile rate, the cost is unrealistic.
Based on the above analysis, it is difficult for GRC lightweight components not to crack. Even if GRC light components do not crack, as the deformation rate is not as large as GRC, the wall surface of component facing materials (such as putty) still cracks, which is obvious in Huijing Villa area. Some cracks are actually just cracks in the decorative materials. Because the wall is light colored paint, a little crack will appear immediately.
If only from the perspective of meeting the use function and safety, small gaps within 0.5mm at the interface of GRC lightweight components should be accepted, which will not affect safety or sound insulation, but will affect the appearance and have a bad psychological impact on users. If it can be achieved, although there are small gaps in the component, there is no surface. This major problem will be solved. Therefore, from trying to prevent GRC lightweight components from cracking to focusing on solving the surface cracks of components.
Based on the above ideas, some companies use anti crack tape to avoid cracking on the surface of components. Due to the good elasticity of the anti crack tape, another remarkable feature is that it can automatically track the deformation. When the gap becomes smaller or disappears, the anti crack tape will rebound automatically, promoting the restoration of the decorative materials on the outer surface, and avoiding the arching of the component surface at the gap. It is very important to strictly control the following two points so that the anti crack tape can play a normal anti crack role.
(1) To ensure the sticking quality of anti crack tape, it needs to be firm and flat. Both sides of the anti crack tape shall be firmly pasted to avoid bubbles, bulges, etc. So as not to affect the anti cracking effect of the anti cracking tape.
(2) The quality of decorative materials for lightweight components shall be qualified. The basic principle of anti crack adhesive tape is to prevent decorative materials from cracking by reducing deformation. The anti cracking effect of anti cracking tape is related to the quality of decorative materials. The greater the allowable deformation rate of decorative materials, the greater the crack width that can be solved by anti crack tape, and the higher the assurance rate, and vice versa.
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