A Preliminary Analysis On The Cracking Of GRC Component
Domestic GRC Component mainly made of alkali-resistant glass fiber reinforced material, sulphoaluminate low alkalinity cement for the cemented material and mixed with the appropriate aggregate to form the substrate, through the injection, mold casting, extrusion, Production process and made. GRC lightweight panel, GRC composite panel, GRC light panel, with the development of production equipment to improve the equipment, the beginning of the 1990s began to GRC decorative products, in recent years Years began to appear a lot of applications. This paper analyzes the factors that cause the cracking of GRC light members, briefly describes their coping strategies and solutions, and puts forward some suggestions on how to use GRC in combination with the project examples.
Project Nanning Longguang Provence district project the first phase of the building facade with a lot of GRC light components, after the use of a period of time there have been some cracks, the opposite and the residents of the psychological impact of a certain negative. As the GRC Component of the large number of applications in recent years, the industry's understanding of this problem is not enough, so the cracks are more common things. This section makes some preliminary analysis of this issue with reference to some of the better insights and their own design experience in the GRC industry.
2, cracking analysis
The degree of cracking varies greatly from region to region. Especially in the coastal areas of the humid climate, the majority of the year the relative humidity of about 90% of the air, in this high temperature and humid climate, GRC light components of the water content is always high, if not take special drying Measures, components in the natural state of the water content can not be less than the standard 10%. As a result, the South, especially in the coastal areas, is easier to crack. Cracks usually occur at the joints of the members and components as well as the components and beams. The width of the crack is related to the dry shrinkage value, the cold shrinkage value and the lateral length of the member. The vast majority of cracks in the width of 0.5mm or less.
3, the current GRC light component cracking solution
To improve the material of the component should be two main objectives: First, reduce the component shrinkage value, which includes the dry shrinkage and cold shrinkage value to reduce the component shrinkage deformation; the second is to improve the elasticity of components and joints, Extended deformation value. Through this "one by one minus" to try to achieve the component of the shrinkage deformation and tensile deformation of the balance. However, the current GRC Component of the characteristics of the tensile value and the contraction value of the balance is difficult.
In the installation of the components of the article, the current main direction is generally placed on the component joints and sewing materials.
In the premise of the quality of the components themselves, the joints of the components are always weak links, cracks are most likely to be produced here. Simply use the "sticky" approach to prevent cracks more difficult, even in the joints of the joints at the glass fiber cloth is also difficult to solve. The components will shrink, hard pull is difficult to pull, the result is often cracked or component joints crack, because there is no solution to shrinkage and tensile deformation of the balance problem. Not to mention the installation of components need to be up and down, before and after repeated wrong to align, it is difficult to do mortar full, most of the installation and then fill mortar, it is not easy to ensure sticky.
The use of elastic mortar to increase the value of tensile deformation method, just to prevent the workpiece crack in terms of ideas and methods are correct. But there is a contradiction in practice it is difficult to solve, that is, the high elasticity of elastic mortar and the low elasticity of the material surface of the contradiction between the low elasticity. The fineness of the component finishes (such as putty) is so far that there is no elastic mortar so much that the surface of the component will still crack. If this is required to meet the same material to achieve the same high rate of pull, the cost is unrealistic.
Based on the above analysis, it is difficult to do now if the GRC Component are not cracked. Even if the GRC Component do not crack, the deformation rate of the single component finishes (such as putty) is not GRC, the wall surface is still cracked, which is evident in the exterior of Provence. Some cracking is actually only the surface of the material cracking. As the wall surface of the relationship between light-colored paint, so a little crack immediately shown.
From the two aspects of the use of functional and safety considerations, GRC Component of the joints within 0.5mm can be accepted, does not affect the safety, does not affect the sound insulation, but the appearance. To the user's psychological effect is not good. If you can do though there are small cracks inside the component, but the surface is not, the idea of the problem is solved. Therefore, from the original effort to prevent the GRC component do not appear cracking, instead of focusing on component surface cracks.
Based on the above ideas, we can use an anti-crack tape to prevent the surface cracking components. As the cracking tape has a good elasticity, it is another feature is to automatically track the deformation, when the cracks become smaller or disappear, anti-crack tape automatically rebound.
4, combined with the proposal of the GRC use of the Provence project
In the absence of a more effective way to prevent cracking of GRC Component, we believe that the idea of cracking GRC Component is as follows:
(1) the design of the location of the crack prone to use as little as possible with GRC decorative line components, only in a single complex components (such as relief, brackets, etc.) on the use of GRC. A single component connection surface is small, the surface convex surface, not easy to crack.
(2) site on the GRC component connection for some special treatment (such as the use of anti-crack tape), and to ensure that the finishes (especially putty) has a certain flexibility.
(3) as far as possible in the GRC component surface without paint, with small size ceramic mosaic instead, so even if there are subtle cracks are not easy to reveal. There are many factors that cause cracking of the GRC light members, but the main reason is the shrinkage deformation of the components. Components in the shrinkage process will produce shrinkage stress, so that components and connecting materials produce tensile deformation, when the tensile deformation is not enough to offset the shrinkage deformation, the cracks will be generated.
5, the conclusion
In the end, the GRC lightweight component is a new type of wall material which has developed rapidly in recent years. It can effectively reduce the wall after the GRC lightweight member and the external wall The risk of body cracking, coupled with the use of ceramic mosaic instead of part of the paint can basically prevent the facade of the sensory problems. GRC light components is the rapid development of construction, cost savings, to achieve the facade modeling one of the ideal materials, reasonable grasp and application will give the construction project to bring gratifying practical value.