What Factors Affect the Carbonation Rate of GRC Panels: Analysis of Influencing Mechanisms and Key Factors

In the field of building materials, durability and service life have always been core concerns of the industry. As a key performance indicator of glass fiber reinforced concrete (GRC) panels, carbonation speed directly affects their structural stability and decorative effect. This article analyzes the key factors influencing the carbonation speed of GRC panels from three dimensions—material properties, environmental factors, and construction techniques—and, drawing on Qinglong Group's 28 years of industry experience, provides scientific material selection and application recommendations for designers and owners.

The carbonation of GRC panels is essentially a process in which calcium hydroxide in the concrete chemically reacts with carbon dioxide in the air, producing calcium carbonate and water. This process reduces the alkalinity of the material, thereby affecting the interfacial bonding performance between the glass fibers and the cement matrix. When participating in the formulation of the Technical Standard for Building Application of Glass Fiber Reinforced Cement (GRC) (JGJ/T423-2018), Qinglong Group found that the carbonation depth of high-quality GRC panels is typically controlled within 0.5mm/year, while inferior products may reach 2-3mm/year—a difference rooted in the scientific soundness of the material formulation.

Material Formulation: The Core Determinant of GRC Panel Carbonation Resistance

The type and amount of cement are fundamental to carbonation speed. Ordinary Portland cement, due to its higher alkali content, carbonates 15%-20% faster than sulphoaluminate cement under the same conditions. Qinglong GRC panels use custom-grade low-alkali cement combined with self-developed mineral admixtures (Patent No.: ZL20201XXXXXX). By optimizing the proportions of silica fume and fly ash, the cement paste structure becomes denser, reducing the carbon dioxide permeability coefficient by more than 30%. The content and dispersion of glass fibers are equally critical: Qinglong uses imported alkali-free glass fibers with lengths controlled at 12-15mm and a volume content of 4.5%-5%. A three-dimensional mixing process ensures uniform fiber distribution, forming an effective carbonation-resistant network.

Environmental Factors: External Drivers That Accelerate or Delay Carbonation

Temperature and humidity conditions significantly affect the carbonation reaction rate. In environments with 60%-70% relative humidity and a temperature of 25℃, the carbonation reaction is most active, with a speed 3 times that of dry environments. In a commercial complex project in Guangzhou, Qinglong's technical team laminated a 0.2mm-thick UHPC protective layer (compressive strength ≥150MPa) onto the surface of GRC curtain wall panels, reducing the carbonation depth of the panels by 60%. Atmospheric pollutant concentration is equally significant: sulfur dioxide and nitrogen oxides in industrial areas can form acidic media with rainwater, accelerating the carbonation process. This is also a key reason why Qinglong adopted a double-layer sealing strip design in its Saudi Arabia project.

Construction Techniques: The Last Line of Defense in Controlling Carbonation

The curing regime directly determines the early strength development of GRC panels. Qinglong's production base uses a process of 4 hours of steam curing at 90℃ plus 28 days of natural curing, raising the cement hydration degree to over 95% and reducing capillary porosity by 25%. Sealing treatment during installation is equally critical: Qinglong's patented two-component silicone sealant (elongation ≥500%), combined with a breathable backing design, prevents both moisture accumulation that causes internal carbonation and the intrusion of external corrosive media. In a landmark project, this process extended the expected service life of GRC decorative lines from 20 years to more than 50 years.

As a leading enterprise in China's GRC industry, Qinglong Group has always made material durability a core R&D direction. From parametric simulation in the detailed design stage, to fully automated molding equipment in production, to 3D scanning and positioning during construction, a full-chain quality control system has been established. Whether for the curved curtain walls of grand theaters or the irregular components of commercial complexes, Qinglong GRC panels maintain industry-leading carbonation speed while ensuring design freedom through scientific material formulation and process control. Choosing a supplier with full industry-chain service capabilities is key to ensuring the long-term performance stability of GRC components—this is also the value of Qinglong's 28 years of dedication to the UHPC/GRC/GRG/GRP fields.