How Do Large-Area GRC Curtain Walls Solve Thermal Stress Issues?

Solving thermal stress issues in large-area GRC curtain walls requires systematic measures across four dimensions: design, materials, construction, and joints. The core approaches involve four key methods: setting expansion joints, optimizing material performance, using flexible joints, and controlling construction sequencing. Qinglong has successfully applied these technologies to multiple large-area projects, such as the 120,000㎡ GRC roof of the Hainan International Convention and Exhibition Center, which has shown no thermal stress-induced cracking or deformation after years of use.

I. Setting Expansion Joints: Releasing Thermal Deformation

Expansion joints are a key construction detail for relieving thermal stress. Expansion joint spacing: under normal conditions, spacing for flat GRC curtain walls is ≤30m, and ≤25m for double-curved surfaces or high-temperature-difference environments; the Qinglong Hainan project set expansion joint spacing at 25m to suit the tropical high-temperature-difference environment. Expansion joint construction: expansion joints are 20-30mm wide, filled internally with elastic sealing materials (such as foam rods + weather-resistant sealant), with metal cover plates on the outside; Qinglong expansion joints adopt an 'elastic sealing + metal cover plate' combination, accommodating thermal deformation of ±25mm. Zoning: large-area curtain walls are divided into independent zones by expansion joints, each zone sized ≤30m×30m to prevent stress concentration from overall deformation; the Qinglong Shenzhen Longhua Xiangshan Science and Technology Park project was divided into 12 independent zones, achieving significant thermal stress dispersion.

II. Material Performance Optimization: Enhancing Crack Resistance and Deformation Capacity

Material selection and mix optimization can enhance resistance to thermal stress. Fiber content adjustment: increasing alkali-resistant glass fiber content to 2.5-3.0% enhances the tensile strength and toughness of components; Qinglong's large-area projects use 2.8% fiber content, achieving flexural strength ≥20MPa and a 30% improvement in crack resistance. Cementitious system optimization: adding 15-20% silica fume and 10-15% ultra-fine fly ash reduces hydration heat and shrinkage; Qinglong's cementitious system has a shrinkage rate ≤0.03%, reducing thermal deformation by 25%. Aggregate gradation: continuously graded quartz sand improves component density and deformation resistance; Qinglong aggregates have a mud content ≤0.3% and density ≥2.2g/cm³.

III. Flexible Joint Design and Construction Sequencing Control: Reducing Stress Accumulation

Joint design and construction processes affect thermal stress accumulation. Flexible joint design: elastic gaskets (such as rubber pads) are installed at connections between anchors and the main structure, allowing slight component displacement to release thermal stress; Qinglong flexible joints accommodate displacement of ±5mm, reducing stress transfer by 40%. Avoiding rigid connections: minimizing rigid connection methods such as welding, prioritizing slidable connections such as dry-hanging and bolted connections; in Qinglong's large-area projects, dry-hanging connections account for 90%, with rigid connections used only for heavy components. Construction timing: avoiding construction during high or low temperature periods, preferring environments of 15-25℃; the Qinglong Hainan project chose nighttime and early morning construction to reduce stress accumulation from sudden temperature changes. Construction sequence: installation follows a 'middle to both sides' and 'top to bottom' order to prevent deformation caused by local constraints; Qinglong's construction sequence was optimized through finite element analysis, resulting in more uniform stress distribution.