1. Function and standard
Fiberglass mesh cloth is the reinforcing material for the thermal insulation surface of the external wall. Its main functions are: to improve the mechanical strength of the surface layer, ensure the continuity of the resistance of the facing layer, disperse the shrinkage pressure and thermal insulation stress of the surface layer, avoid stress concentration, and resist Surface cracking caused by changes in temperature and humidity in nature and accidental impacts. Therefore, the alkali-resistant glass fiber mesh plays an important function and role in the external thermal insulation system, so the selection of a good glass fiber mesh is also an important part of ensuring the comprehensive quality of the external thermal insulation system.
The current national technical standard for external wall insulation (JG149-2003): the alkali-resistant tensile breaking strength of glass fiber mesh in the warp and weft directions shall not be less than 750N/50mm, and the retention rate of alkali-resistant tensile breaking strength shall not be less than 50%, per square meter Rice weight ≥ 130 grams. The JG158-2004 glass fiber mesh warp and weft alkali-resistant tensile breaking strength 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 in the external wall insulation system in my country's market weighs about 130 grams per square meter, and its strength is generally low. Its normal fracture strength is only 1000N/5cm, or even lower. For this reason: the technical indicators of the grid cloth for the external wall insulation project require standardization, and the qualification confirmation of the purchased alkali-resistant glass fiber mesh cloth must be made before use. In the crack control of external wall insulation, not only the insulation layer material must have a certain tensile strength and ultimate tensile strength, but also the anti-crack protective layer material must have sufficient tensile strength. For this reason, when selecting alkali-resistant fiberglass mesh, it is necessary to pay attention to whether the tensile strength of the alkali-resistant fiberglass mesh itself meets the standard.
2. The use of alkali-resistant glass fiber mesh cloth compounded in plastering mortar
On the one hand, it can effectively increase the tensile strength of the protective layer. On the other hand, because it can effectively disperse the stress, it can disperse the wide cracks that may have been generated into many smaller cracks, thereby forming its crack resistance. The surface coating material and coating amount are of great significance to the alkali resistance of glass fiber mesh, and the glass fiber variety has decisive significance for long-term alkali resistance.
During the use of glass fiber mesh：
The overlap width between the alkali-resistant mesh cloths is not less than 50mm, and the alkali-resistant mesh cloths at the inner corners should be overlapped with stubble, and the width is ≥50mm, and the outer corners are ≥200mm. During construction, the alkali-resistant grid cloth should be laid flat, without wrinkles, and the mortar must be full.
3. How to identify the quality problems of alkali-resistant glass fiber mesh
① Glass fiber mesh cloth Its glass fiber is usually made of waste glass such as beer bottles. The production process is clay crucible drawing, which is a production process prohibited by the state, and the surface coating is not alkali-resistant emulsion. From an intuitive point of view: the workmanship is relatively rough, generally sold more in the market, often appear insufficient length, insufficient weight, broken after two folds, loose joints are easy to shift, and easy to puncture the skin. This kind 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 glass fiber yarn will become powder with a light grinding.
② There is another kind of imitation platinum fiberglass mesh cloth, also called mixed silk yarn. This is a relatively good imitation glass fiber, but it is usually some flat glass cullet with good transparency in the selection of waste glass, and the fiber diameter is relatively small. 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 external wall insulation.
③ The standard mesh with good quality uses platinum glass fiber as the base material, and both the material selection and the weaving process are more particular. All coating emulsions used have good alkali resistance. Excellent alkali resistance and high warp and weft tensile strength make the product have good hand feeling and good construction compliance, which can greatly reduce the amount of plastering mortar.
④ The scope of use of alkali-resistant glass fiber mesh cloth in external thermal insulation systems:
External wall insulation is usually used: 3 × 3 × 45 grams, 5 × 5 × 80 grams;
The thermal insulation system of the exterior wall panels adopts: 5×5×130 grams, 5×5×145 grams;
The exterior wall rubber powder particle system adopts: 5×5×160 grams;
Exterior wall tile facing or insulation layer up to two meters: 3×7×10×300 grams.
