How Does the Thermal Expansion Coefficient of Exterior Wall GRC Affect Construction?

The coefficient of thermal expansion (CTE, typically around 1.0×10⁻⁵/℃) of GRC material is the inherent physical property that causes it to expand and contract under temperature changes. This characteristic has a decisive impact on construction design, particularly "joint width setting, connection node design, and installation season selection". Ignoring the effects of thermal expansion may cause joint sealant to be torn apart or bulge under compression, generate thermal stress inside components, or even cause damage. In its detailed design and construction guidance, Qinglong Group makes thermal deformation calculation a mandatory step to ensure that the curtain wall system can safely adapt to seasonal temperature variations.

Decisive Impact on Joint Width Design

This is the most direct impact. The joint width reserved during construction must accommodate the maximum expansion and contraction of GRC panels under extreme annual temperature differences. The calculation formula is: ΔL = α × L × ΔT, where α is the coefficient of thermal expansion, L is the panel length, and ΔT is the extreme annual temperature difference (the panel surface temperature rise caused by solar radiation must be considered, typically 20-30℃ higher than the air temperature). For example, a 2-meter-long panel in a region with an annual temperature difference of 50℃ has a theoretical deformation of ΔL = 1.0e-5 2 50 = 1.0mm. The designed joint width must be greater than this value, with allowance left for the sealant's movement capability (typically ±25%). Qinglong will precisely calculate and determine the joint width for each type of panel based on the climate data of the project site.

Strict Requirements for Connection Node Design

Connection nodes must allow GRC panels to "breathe" freely, i.e., produce slight movements, rather than forming rigid constraints. Therefore, the connection between anchors and the framing is usually designed with slotted holes, allowing panels to slide within a certain range. Fixing bolts must not be overtightened, and elastic washers sometimes need to be added. The connection between embedded parts and anchors should also have a certain rotational capability to release the bending stress caused by temperature gradients. Rigid connections would fully transfer thermal stress to the panels or framing, resulting in cracking or deformation.

Special Considerations for Installation Timing and Techniques

When installing under extreme temperatures, the deformation direction of components under future temperature changes must be considered. For example, when installed at low winter temperatures, joints should be in their "widest" state, because the panels will expand when temperatures rise in summer, narrowing the joints. Conversely, summer installation must ensure that joints retain sufficient allowance for "narrowing". Qinglong's construction plans will specify the installation joint width at the reference temperature and guide fine adjustments in different seasons. Through scientific calculation and refined node design, GRC facades can fully and harmoniously cope with thermal expansion and contraction, achieving long-term safety and stability.