Alkali-resistant glass fiber mesh cloth is a rib material for reinforcing cement (concrete). Its notable feature is that 16.5% zirconia is introduced into the glass component, which can effectively resist the erosion of alkaline substances in cement, thereby improving the quality of cement mortar. Impact resistance, tensile resistance, bending resistance, crack resistance, and impermeability are recognized and favored by experts in the fields of construction and material science.
Driven by the national energy conservation and environmental protection policy, external wall insulation technology has developed rapidly. The "polystyrene board polymer mortar external thermal insulation system" and "rubber powder polystyrene particle thermal insulation slurry system" approved by the Ministry of Construction have been widely used in various public and residential buildings across the country. One thing they have in common is that the surface layer is made of cement and additives as the cementitious material, and the alkali-resistant glass fiber mesh is used as the reinforcing material to form a protective cover outside the insulation layer. This not only solves the generation of micro-cracks in the solidification process of cement polymer slurry, but also ensures that the plastering surface layer has no cavities, no cracks, no falling off, and avoids damage to the insulation layer by harsh weather conditions.
The core of the entire external wall thermal insulation system is thermal insulation, and the key depends on the reinforcing effect of the material. Alkali-resistant glass fiber mesh cloth is unmatched by other reinforcing materials. Because:
1. The reinforcement effect of alkali-resistant glass fiber mesh cloth is obvious, which can increase the tensile strength of cement polymer mortar by more than 3 times, the bending strength by more than 4 times, and the impact strength by more than 20 times. The elastic modulus of alkali-resistant glass fiber mesh cloth is 80 MPa, and the elongation at break is less than 2.4%, which is equivalent to the expansion and contraction coefficient of cement polymer mortar. 90-degree deformation is required to avoid the disadvantages of using metal nets to produce cavities.
2. The alkali resistance of alkali-resistant glass fiber mesh cloth is better than that of the medium, alkali-free, and alkali-resistant coated mesh cloth. The fundamental difference between them is that there is a zirconium-rich interface on the surface of the alkali-resistant glass fiber, which can reduce the concentration of hydroxide ions in the alkali solution and inhibit its diffusion speed on the surface of the glass fiber, thereby improving the alkali resistance of the glass. Research by the National Institute of Building Materials has proved that the strength half-life of alkali-resistant glass fiber mesh can reach 100 years. The medium and alkali-free glass fiber mesh cloth is covered with a layer of chemical anti-corrosion gel coat (mostly PVC resin) on the surface of the fabric with the help of physical strength. Once this layer of "coat" is damaged by an external force during handling and on-site construction, its alkali resistance Sex will not be guaranteed. European and American professional companies promise only 20 to 30 years of safety period for the strength of the mesh cloth used. The main reason is that there is no scientific basis for the alkali resistance of medium and alkali-free coated mesh cloth.
3. There is a big difference in the retention rate of alkali-resistant strength between alkali-resistant glass fiber mesh cloth and medium-, alkali-free, and alkali-resistant coated mesh cloth. According to the test of the alkali resistance strength retention rate by the National Building Materials Research Institute Testing Center and the Beijing Building Materials Inspection Station, the alkali resistance strength retention rate of the former is greater than 90%, and the latter is less than 70%. It has been proved that as long as the content of zirconia is greater than 14.5%, It can ensure that the alkali resistance strength retention rate is greater than 90%. However, it only takes 1 to 2 days to detect the content of zirconia by chemical method, which is convenient and fast, making it extremely easy for testing agencies and construction companies to identify the best.
4. The alkali-resistant glass fiber mesh market has been severely impacted. Since the cost of mesh cloth accounts for about 4% of the engineering cost of the external wall insulation system, the cost of alkali-resistant mesh cloth is only 0.4% higher than that of medium and alkali-free mesh cloth, but it does not guarantee the safety of the entire system.
With the development of my country's energy-saving and thermal insulation technology and the recognition of the performance of alkali-resistant glass fiber by people in the building materials and construction industry, it will definitely promote the development of the external wall thermal insulation system in a healthy, orderly, and safer direction.
