How Does the Thermal Expansion Coefficient of Exterior Wall GRC Affect Construction? Analysis of GRC Thermal Deformation Control Technology

The thermal expansion coefficient of GRC is 1.0-1.2×10⁻⁵/℃, essentially consistent with the concrete substrate (1.0×10⁻⁵/℃), which is a significant advantage for its use as an exterior wall material. However, under large panel sizes and large temperature differences, the effects of thermal deformation still need to be considered. For every meter of length, a 40℃ temperature change produces deformation of 0.4-0.5mm, which must be absorbed through joint design.

Joint width calculation formula: δ=α×L×ΔT+δ₀, where δ₀ is the construction error allowance (generally taken as 2-3mm). In one project with 3m panels and an annual temperature difference of 50℃, the calculated joint width required 12mm, and 15mm was actually adopted. After 5 years of use, the joints remain intact with no compression deformation.

Deformation Calculation

Calculate the deformation based on the local maximum temperature difference and the panel size. The temperature difference value should account for the temperature rise caused by solar radiation, which is typically 15-20℃ higher than the air temperature.

Joint Design Principles

The joint width should be greater than 1.5 times the calculated deformation, and no less than 10mm. Joint spacing generally does not exceed 12m and should be aligned with structural joints.

Connection System Design

Connectors should allow panels to expand and contract freely, with movement capacity of no less than 1.2 times the calculated deformation. Avoid rigid connections that cause thermal stress concentration.

Seasonal Construction Measures

In summer construction, appropriately increase joint widths; in winter, appropriately reduce them. Record the temperature at installation as a reference baseline for in-service deformation.

Thermal deformation control is key to GRC exterior wall design. Scientific calculation and rational detailing can prevent thermal stress problems.