Analysis of the Construction Process and Key Technical Points for Replacing a Single Damaged UHPC Curtain Wall Panel

In the field of architectural decorative materials, material durability directly affects a building's safety and aesthetics. Among these materials, GRC panels (Glass Fiber Reinforced Concrete) are composite materials widely used in exterior wall cladding, shading systems, landscape projects and other applications, and their carbonation rate is a key indicator of service life. As an industry expert with 28 years of full-chain experience in UHPC/GRC/GRG/GRP materials, Qinglong Group will analyze in depth—from the three dimensions of material properties, environmental factors, and process control—the core factors affecting the carbonation rate of GRC panels and their mechanisms, providing designers and owners with scientific material selection and application guidance.

The Essence of GRC Panel Carbonation: The "Aging Code" of Cement-Based Materials

The carbonation of GRC panels is essentially a chemical reaction in which calcium hydroxide in the concrete reacts with carbon dioxide in the air to produce calcium carbonate and water. This reaction lowers the alkalinity of the material, which in turn affects the interfacial bond between the glass fibers and the cement matrix, and over time may cause problems such as strength loss and surface cracking. While participating in drafting the Technical Standard for Architectural Application of Glass Fiber Reinforced Cement (GRC) (JGJ/T423-2018), Qinglong Group found that the carbonation depth of high-quality GRC panels should be controlled within 0.5mm per year, while in actual projects, differences in material formulations and environmental conditions can cause the carbonation rate to fluctuate by a factor of 3-5.

Material Formulation: The "Genetic Code" Determining the Carbonation Resistance of GRC Panels

1. Cement Type and Admixture Ratio: Using high-alumina cement or sulphoaluminate cement can improve matrix density, reducing the carbonation rate by more than 40% compared with ordinary Portland cement. At its Nanning production base, Qinglong incorporates active admixtures such as silica fume and mineral powder to keep the porosity of GRC panels below 15%, effectively hindering CO₂ penetration.

2. Glass Fiber Type and Content: The addition of alkali-resistant glass fiber (AR glass fiber) not only improves flexural strength (up to over 20MPa); its mesh distribution also forms a physical barrier that delays the carbonation process. Through 28 years of process optimization, Qinglong has established a golden ratio of 5-8% fiber content, maximizing carbonation resistance while ensuring toughness.

3. Water-Cement Ratio and Admixtures: A low water-cement ratio (≤0.45) combined with high-efficiency water reducers can significantly reduce capillary channels. Qinglong's independently developed GRC-specific modifier can increase the material's early strength by 30% and reduce the moisture conditions required for carbonation reactions.

Environmental Factors: The "External Drivers" That Accelerate or Delay Carbonation

1. Combined Effect of Temperature and Humidity: For every 10℃ rise in temperature, the carbonation reaction rate increases 1-2 times; carbonation is fastest at a relative humidity of 50-70%. Take a landmark project in Saudi Arabia undertaken by Qinglong as an example: the hot, dry environment reduced the carbonation rate of GRC panels by about 60% compared with coastal regions of China, confirming the importance of environmental control.

2. CO₂ Concentration and Air Pollution: CO₂ concentration in urban industrial areas is 30-50% higher than in suburban areas, and the carbonation rate increases accordingly. Meanwhile, acidic gases such as SO₂ and NOx react with the cement matrix to form soluble salts, damaging the dense structure and indirectly accelerating carbonation. In the Century Plaza renovation project on Nanjing East Road, Qinglong applied a fluorocarbon surface coating, improving the pollution resistance of GRC panels by 50%.

3. Ultraviolet Rays and Wet-Dry Cycling: Long-term UV exposure ages surface resin coatings and intensifies moisture penetration, while frequent wet-dry cycles repeatedly expand and contract the pore structure, creating channels for CO₂ diffusion. Qinglong's double-curved GRC components adopt a three-layer protective system (primer + intermediate coat + topcoat), achieving 15 years with no obvious carbonation in projects such as the Canton Tower.

Process Control: The "Quality Control Shield" Safeguarding Carbonation Resistance Across the Entire Chain

1. Density Control in Production: Qinglong uses a vacuum extrusion molding process to raise the bulk density of GRC panels to above 2.1g/cm³, combined with steam curing (80℃, 6 hours) to ensure full cement hydration and reduce internal defects.

2. Sealing Treatment of Installation Joints: Anchoring joint designs are optimized using BIM technology, and elastic sealant is used for joint caulking to prevent rainwater infiltration that could cause internal carbonation. In the Dongguan Women and Children's Activity Center project, Qinglong innovatively applied a "breathing curtain wall" system, keeping the cavity behind the GRC panels in a dry, slightly positive-pressure environment.

3. Scientific Intervention in Later-Stage Maintenance: A regular inspection mechanism is established (carbonation depth testing every 3 years), with timely repair of surface damage. Qinglong's after-sales maintenance services include a special anti-carbonation repair mortar that can restore more than 90% of the protective performance in locally carbonated areas.

As a national "Specialized, Refined, Distinctive, and Innovative" enterprise, Qinglong Group has always made material durability research its technical core. From formulation optimization of GRC panels to full life-cycle management of engineering applications, every step embodies 28 years of accumulated industry experience. Choosing Qinglong GRC means not only choosing a building material, but choosing an anti-carbonation solution verified by more than a thousand projects. Looking ahead, Qinglong will continue its mission of "Creating Beautiful Architecture," driving technological breakthroughs in the durability of UHPC/GRC/GRG/GRP materials and providing more reliable products and services for the global architectural decoration industry.