The external wall insulation system consists of many types of materials, including insulation board, adhesive, mesh cloth, wood fiber, bonding mortar, plastering mortar, coating (ceramic tile), etc. Each material must be applied according to the requirements. For example, insulation board is most commonly stacked in the open air at many construction sites. The insulation board is exposed to sunlight and rain, which can easily cause deformation and shrinkage of its structure. Additionally, if the surface of the insulation board becomes dirty, it can negatively affect the bonding strength.
In particular, there are gaps between the insulation boards, and filling the gaps with mortar is likely to cause regular cracks on the surface of the plastering mortar; the bonding area of the insulation board is too small, and hollowing during the pasting process will also affect the bonding strength. If the hollowing is obvious, cracks may appear on the surface. The plastering mortar layer is too thin to cover the insulation board. After the paint is applied, obvious traces of alkali-resistant glass fiber mesh cloth and anchor bolts are likely to appear. If the plastering mortar layer is too thick or if the second layer is applied before the first layer has completely dried, shrinkage cracks are likely to occur.
In the external wall insulation system, the Yintong YT inorganic active wall insulation system is a new type of mesh-free insulation system that does not require mesh cloth or rivets. In addition to the Yintong YT system, other external wall insulation systems must use glass fiber mesh cloth with a certain alkali resistance. If a glass fiber mesh cloth containing a certain amount of zirconium is used, the alkali resistance of the mesh and the long-term stability of the entire external wall insulation system can be significantly improved. This type of product plays a great role in improving the strength of the entire system. Another issue worthy of attention is the existence of ice flowers. The formation of ice flowers is mainly due to the traces left on the mortar surface after the free water in the mortar suddenly freezes and forms icicles when the temperature is below the freezing point.
The cementitious material used in the external wall insulation system is generally ordinary silicate cement, and the hydration of cement at low temperatures progresses very slowly, and the early strength development is slow. If it encounters freezing temperatures, it will undoubtedly make things worse. Once the free water that has not yet hydrated in the cement mortar freezes and expands, it will cause devastating damage to the mortar structure that has not yet formed sufficient strength. The final result is that the constructed mortar has no strength.
It is recommended to strictly adhere to the technical specifications outlined in the JGJ144-2004 standard. Once the ambient temperature is lower than 5 degrees Celsius, the construction of non-antifreeze cement mortar on the exterior wall should be stopped immediately. For the exterior wall insulation system project that has suffered freeze-thaw damage, it is recommended to take appropriate remedial measures for repair, depending on the degree of damage. If the damage is serious, it is recommended to tear it down and reconstruct it.
