GRC At the beginning of use, component cracking was a common problem in the construction industry. There are very few experienced manufacturers in the industry, so we don't know why, let alone what to do. Now this problem has had results, Baotou GRC It is considered that the fundamental solution to cracking of GRC lightweight components is to improve the material properties, installation and structure of components, as follows:
To improve the material properties of components, two goals should be achieved: one is to 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", the balance between the shrinkage deformation and tensile deformation of the component is achieved as far as possible. However, the characteristics of GRC lightweight components make it difficult to balance the tensile value and the shrinkage value.
In terms of the installation and construction of components, the current main direction of attack is generally on the treatment of component joints and joint materials.
On the premise that the quality of the component itself is qualified, the joint of the component is always a weak link, and cracks are easy to occur here. It is difficult to prevent cracks by simply using the method of "sticking", even if glass fiber cloth is pasted at the joints of components for reinforcement. The component will shrink, and it is difficult to pull by hard pulling. As a result, the component often cracks or the component seam cracks, because the balance problem between shrinkage deformation and tensile deformation has not been solved. What's more, the components need to be staggered up and down, back and forth repeatedly to align, so it is difficult to achieve full mortar. Most of them are filled with mortar after installation, so it is not easy to ensure adhesion.
The idea and method of using elastic mortar to increase the tensile deformation value is correct in terms of preventing cracking of member joints alone. But in practice, there is a contradiction 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 rate of component facing materials (such as putty) is far less than that of elastic mortar, and the component surface will still crack. For this reason, it is unrealistic in cost to require the facing materials to reach the same high pulling rate.
Based on the above analysis, it is really difficult to prevent GRC lightweight components from cracking at present. Even though GRC lightweight components do not crack, the wall surface still cracks because the deformation rate of component facing materials (such as putty) is not as large as GRC, which is obvious in Huijing villa area. In fact, some cracks are just cracks in the decorative materials. Because the wall surface is covered with light colored paint, a little crack will appear immediately.
If only from the two aspects of meeting the use function and safety, small cracks within 0.5mm at the joints of GRC lightweight components should be acceptable, which will not affect safety or sound insulation, but will affect the appearance and have a bad psychological effect on users. If we can achieve that although there are small cracks in the component, there are no surface cracks, the main problem will be solved. Therefore, instead of trying hard to prevent GRC lightweight components from cracking, the focus is on solving the surface cracks of components.
Based on the above idea, some companies use a kind of anti crack tape to prevent the surface of components from cracking. Due to the good elasticity of the anti crack tape, another remarkable feature of the anti crack tape is that it can automatically track the deformation. When the crack becomes small or disappears, the anti crack tape automatically rebounds, driving the decorative materials on the outer surface to restore the original state, avoiding the arching of the component surface at the crack. In order to make the anti crack tape work normally, it is critical to strictly control the following two points.
(1) Ensure the sticking quality of the anti crack tape, which needs to be stuck firmly and flat. The two sides of the anti crack tape shall be firmly stuck to prevent bubbles, bulges, etc. So as not to affect the anti cracking effect of the anti cracking tape.
(2) The quality of finishing materials for lightweight components shall be qualified. The basic principle of anti crack tape is to prevent the facing material from cracking by reducing deformation. The anti cracking effect of the anti cracking tape is related to the quality of the facing materials. The greater the allowable deformation rate of the facing material, the greater the crack width that the anti crack tape can solve, the higher the assurance rate, and vice versa. Therefore, it is very important to monitor the quality of finishing materials (especially putty) while using anti crack tape.
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