1. Functions and standards
Fiberglass mesh cloth is a reinforcing material for the exterior wall insulation surface layer. Its main functions are: improving the mechanical strength of the surface layer, ensuring the resistance continuity of the facing layer, dispersing the shrinkage pressure and insulation stress of the surface layer, avoiding stress concentration, and resisting Surface cracking caused by changes in natural temperature and humidity and accidental impact. Therefore, alkali-resistant fiberglass mesh cloth plays an important role in the external insulation system, so the selection of good fiberglass mesh cloth is also an important part of ensuring the overall quality of the external insulation system.
The current national technical standard for external wall insulation (JG149-2003): the alkali-resistant tensile breaking strength of the glass fiber mesh in the warp and weft directions shall not be less than 750N/50mm, and the alkali-resistant tensile breaking strength retention rate shall not be less than 50%, per square meter Rice weight ≥130 grams. The alkali-resistant tensile breaking strength of JG158-2004 glass fiber mesh in both the warp and weft directions shall not be less than 1250N/50 mm, the alkali-resistant tensile breaking strength retention rate shall not be less than 90%, and the weight per square meter shall be ≥160 grams.
At present, the mesh cloth used for exterior wall insulation systems on the Chinese market weighs about 130g per square meter, and its strength is generally low. Its normal fracture strength is only 1000N/5cm, or even lower. To this end: the technical indicators of mesh cloth for exterior wall insulation projects are required to be standardized, and the purchased alkali-resistant fiberglass mesh cloth must be qualified before use. When controlling cracks in external wall insulation, not only the insulation layer material is required to have a certain tensile strength and ultimate stretch, but the crack-resistant protective layer material is also required to have sufficient tensile strength. For this reason, when choosing alkali-resistant fiberglass mesh, it is necessary to pay attention to whether the tensile strength of the alkali-resistant fiberglass mesh itself meets the standards.
2. The use of alkali-resistant fiberglass mesh compounded in the plastering mortar can effectively increase the tensile strength of the protective layer. On the other hand, it can effectively disperse stress and disperse wider cracks that may otherwise occur. It forms many fine cracks, thereby forming its anti-cracking effect. The surface coating material and coating amount are of great significance to the alkali resistance of fiberglass mesh, and the fiberglass variety is decisive for long-term alkali resistance.
During the use of fiberglass mesh cloth:
The overlap width between alkali-resistant mesh cloths is not less than 50mm. The alkali-resistant mesh cloths at the inner corners must be pressed and overlapped. The width is ≥50mm and the width at the outer corners is ≥200mm. During construction, the alkali-resistant mesh cloth should be laid flat, without wrinkles, and the mortar should be full. At the same time, it should be smoothed and straightened, and the squareness and verticality of the yin and yang corners should be maintained.
3. How to identify quality problems of alkali-resistant fiberglass mesh:
① The market price of the worst fiberglass mesh cloth is usually around 1.00 yuan to 1.60 yuan. Its fiberglass fiber is usually made from waste glass such as beer bottles. The production process is clay crucible drawing, which is a production process prohibited by the state. , the surface coating is also not an alkali-resistant emulsion. From an intuitive point of view: the workmanship is relatively rough, and generally sold in large quantities in the market. The length is often insufficient, the weight is insufficient, and it breaks after folding twice. The joints are not strong and easy to shift, and it is easy to puncture the skin. This type of mesh cloth generally loses its strength after two months when used in the insulation layer. If the mortar is knocked out and the mesh cloth is taken out, the fiberglass yarn will turn into powder with just a slight grinding.
② There is another kind called imitation platinum fiberglass mesh cloth, also called mixed silk yarn. This is a relatively good imitation of glass fiber, but it is usually made from flat broken glass with good transparency, and the fiber diameter is relatively thin. Sometimes it is difficult to judge its authenticity from the surface, but its quality cannot meet the requirements of real alkali-resistant mesh cloth in exterior wall insulation.
③ Standard high-quality mesh cloth uses platinum glass fiber as the base material. Both the selection of materials and the weaving process are very particular. The coating emulsions used have good alkali resistance. The excellent alkali resistance and high longitudinal and latitudinal tensile strength make the product have a good hand feel and good construction conformity, and can greatly reduce the amount of plastering mortar.
④ The scope of use of alkali-resistant fiberglass mesh in external insulation systems:
Internal insulation of exterior walls usually uses: 3×3×45g, 5×5×80g
The exterior wall panel insulation system adopts: 5×5×130g, 5×5×145g
The exterior wall rubber powder particle system adopts: 5×5×160 grams
Exterior wall tile facing or insulation layer below two meters: 3×7×10×300g
