Glass yarn should be used to prevent cracking of external insulation system

Breaking strength and alkali resistance strength retention rate are important properties of glass yarn. Breaking strength is inseparable from glass count or weight. At present, the glass yarn used for exterior wall insulation systems on the Chinese market generally weighs about 130g per square meter, and its strength is generally low. Its normal breaking strength is only about 1000N/5cm. In Europe or the United States, where exterior wall insulation technology and regulations are relatively mature, the requirements for the breaking strength of Fiber Glass are much higher than in my country. The German Building Technology Board (DIBt) requires that the normal breaking strength of glass yarn used for exterior wall insulation systems is ≧1750N/5cm, and the alkali resistance retention rate is ≧50%. If domestic products meet this requirement, the weight of glass yarn per square meter must be above 160g.

Improving breaking strength standards is undoubtedly necessary. Especially polymer cement plaster mortar with higher cement content and cement strength grade. The damage caused by these things to the Fiber Glass is not only chemical corrosion, but also the crystallization pressure corrosion of calcium hydroxide and calcium sulfoaluminate. At the same time, the high water absorption rate of mineral materials also has a negative impact on the glass yarn. Experiments have shown that after soaking in distilled water, the strength of the Fiber Glass will be lost by about 30%.
Our country currently lacks standards for glass yarn specifically used for exterior wall insulation systems, especially the alkali-resistant strength retention rate and alkali-resistant test methods. The alkali solutions used by testing agencies or manufacturers in various places vary, and NaOH solutions are used. There are 80℃ cement slurry and NaOH, KOH, Ca(OH)2 mixed alkali solution. Since the formulation of this performance index has a great impact on the performance trend, price, and market affordability of products on the market, relevant research units must conduct a unified investigation of the performance of domestic Fiber Glass, refer to foreign standards, and formulate Standards suitable for our country`s national conditions.
Cement-free pure polymer plastering mortar has no alkali corrosion and low water absorption. The glass yarn can function normally in it for a long time, which is undoubtedly the safest for the long-term crack resistance of the protective surface layer.