Analysis of Causes and Discussion of Solutions for Thermal Stress Problems in Large-Area GRC Curtain Walls

Solving the Thermal Stress Challenge of GRC Curtain Walls: A Full-Chain Solution from Material Genes to Engineering Practice

In contemporary building envelope design, GRC (glass fiber reinforced concrete) has become the preferred curtain wall material for high-end buildings such as grand theaters and convention centers, thanks to its exceptional sculptural expressiveness and durability. However, when large-area GRC curtain walls develop cracking, deformation, or other problems in environments with drastic temperature changes, it not only compromises the building's aesthetics but may also create hidden safety hazards. As an industry technology leader with 28 years of full-chain experience in UHPC/GRC/GRG/GRP materials, Qinglong Group, drawing on the practice of hundreds of landmark projects, provides an in-depth analysis of the underlying logic of thermal stress problems and proposes a systematic solution.

### I. Causes of Thermal Stress in GRC Curtain Walls: The Dual Challenge of Material Properties and Environmental Loads

GRC material is composed of a cement-based matrix combined with glass fibers, and its thermal deformation characteristics arise from the interaction between the material's intrinsic properties and the external environment. When ambient temperature changes, GRC panels expand and contract; if the constraint conditions of the curtain wall system (such as keel fixing methods and panel jointing techniques) fail to release the stress, interface cracking or overall deformation can easily occur. In a coastal cultural center project, a 3000㎡ GRC curtain wall developed through-going cracks at panel joints because the extreme condition of a 25℃ temperature difference during typhoon season had not been taken into account—a typical case of accumulated thermal stress. Through material thermal expansion coefficient testing (GRC standard value approx. 8-10×10⁻⁶/℃) and structural mechanics simulation, the Qinglong technical team found that thermal stress is positively correlated with panel size, installation gaps, and elastic modulus, with stress concentration risk being particularly prominent for extra-long continuous panels (over 6m).

### II. Material Optimization: Stress Control Strategies from Formulation Design to Process Innovation

The key to solving the thermal stress challenge lies in improving crack resistance at the material source. Relying on the R&D strength of its provincial-level engineering technology center, Qinglong Group has achieved breakthroughs through three technical paths: first, adopting a low-alkali sulphoaluminate cement matrix to reduce the peak hydration heat by 30%, thereby reducing internal thermal stress; second, incorporating nano-scale silica fume and ultra-fine steel fibers to raise GRC flexural strength to above 25MPa and increase fracture toughness by 40%; third, innovating a “gradient reinforcement” process that arranges high-density glass fiber mesh on the panel surface to form a stress buffer zone. In a commercial complex project in Guangzhou, a GRC curtain wall using this formulation underwent temperature cycling tests from -5℃ to 40℃, with deformation controlled within 0.3mm/m—far better than industry standards. In addition, Qinglong's self-developed UHPC-GRC composite panel, which combines a UHPC thin layer (5-8mm) with a GRC substrate, retains GRC's sculptural advantages while leveraging UHPC's low expansion coefficient (approx. 4.5×10⁻⁶/℃) to achieve coordinated control of thermal deformation.

### III. Engineering Practice: Full-Process Management to Build a Thermal Stress Solution

A systematic solution must cover the entire chain of design, production, and installation. During the detailed design stage, Qinglong uses BIM + parametric technology to simulate the temperature field of the curtain wall and optimize joint spacing (recommended no more than 4.5m) and expansion joint details—for example, using “floating” anchor nodes that allow ±20mm of horizontal displacement. In the production stage, steam curing precisely controls the cooling rate (≤5℃/h) to prevent micro-cracks caused by sudden heating and cooling. During installation, 3D laser scanning positioning technology is applied innovatively to ensure panel gap tolerances of ≤2mm, and elastic sealant (movement capability ≥25%) is used to fill the joints, forming a flexible buffer. In a grand theater project in Nanning, through this full-process management, the Qinglong team ensured that the 12000㎡ double-curved GRC curtain wall developed zero structural cracks after three years of seasonal testing, earning the “China Steel Structure Gold Award.”

### IV. Industry Outlook: Driving the Sustainable Development of GRC Curtain Walls Through Technological Innovation

As building envelope design evolves toward super-large scales and complex forms, thermal stress control has become the core issue in GRC curtain wall technology upgrades. As a participating unit in the Technical Standard for Building Application of Glass Fiber Reinforced Cement (GRC) (JGJ/T423-2018), Qinglong Group is promoting the inclusion of thermal stress calculation as a mandatory clause in the specification. In the future, by introducing intelligent monitoring systems (such as fiber Bragg grating sensors) for real-time stress monitoring, combined with the composite application of UHPC/GRC/GRP materials, curtain wall systems will achieve the leap from “passive crack resistance” to “active early warning.” As advocated by the Qinglong mission of “Creating Beautiful Architecture,” only by deeply integrating materials science with engineering practice can GRC curtain walls find the perfect balance between aesthetic expression and structural safety, injecting lasting vitality into modern architecture.