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

In the field of building materials, the durability of a material directly affects building safety and service life. As one of the key properties of GRC materials, the carbonation rate not only affects mechanical performance but also determines the long-term stability of architectural decorative effects. Starting from the nature of the material, this article analyzes in depth the core factors affecting the carbonation rate of GRC panels, providing a scientific reference for industry peers.

Carbonation Mechanism of GRC Panels: The "Breathing" Process of Cement-Based Materials

The carbonation of GRC panels is essentially a chemical reaction between carbon dioxide in the air and cement hydration products. When CO₂ penetrates into the material and reacts with components such as calcium hydroxide to form calcium carbonate, this process lowers the alkalinity of the material, which in turn affects the interfacial bonding performance between the glass fibers and the matrix. Through 28 years of in-depth GRC design and production practice, Qinglong Group has found that normal carbonation can form a dense protective layer on the material surface, while excessive carbonation causes strength loss; therefore, balancing the carbonation rate is key to ensuring the durability of GRC panels.

Raw Material Proportions: The Inherent Genes Determining the Carbonation Rate of GRC

The type and amount of cement directly affect the matrix of the carbonation reaction. Because the hydration products of high-alumina cement have lower alkalinity, its carbonation sensitivity is significantly higher than that of ordinary Portland cement. Through orthogonal tests, Qinglong's production base found that when cement content is controlled at 400-450kg/m³, strength is ensured while the carbonation process is delayed. Glass fiber content is equally critical: high-quality alkali-resistant glass fiber (e.g., with zirconia content ≥16%) is highly stable in alkaline environments and can effectively resist interfacial degradation caused by carbonation, which is one of the core technologies enabling Qinglong GRC products to maintain structural integrity over the long term.

Microstructure: The "Regulating Valve" of Pore Characteristics and Carbonation Paths

The porosity and pore size distribution of the material serve as a "channel map" for CO₂ diffusion. Tests by Qinglong's R&D center using the mercury intrusion method show that when the porosity of GRC panels is ≤18% and the average pore size is <50nm, the carbonation depth can be controlled within 0.5mm per year. In production, optimizing the sand-cement ratio (1.5-2.0) and incorporating mineral admixtures such as silica fume can significantly refine the pore structure. In addition, the steam curing regime has a significant impact on the microstructure: Qinglong's original "stepped temperature control" steam curing process reduces the 28-day carbonation depth of GRC panels by 30% compared with the industry average.

Environmental Factors: How External Conditions Accelerate or Inhibit Carbonation

Temperature and humidity are important external variables affecting the carbonation rate. The carbonation reaction is most intense in environments with a relative humidity of 60%-70% and a temperature of 25℃. Monitoring data from Qinglong's overseas projects show that the annual carbonation depth of GRC panels in Malaysia's tropical climate is 15%-20% higher than in temperate regions of China. Elevated atmospheric CO₂ concentration also accelerates carbonation, with the carbonation rate of GRC components in industrial areas 25% higher than in suburban areas. For extreme environments, Qinglong provides customized protection solutions; for example, silane impregnation treatment adopted in a Middle East project reduced the carbonation rate by more than 40%.

Engineering Practice: Full-Chain Control from Laboratory Data to Project Implementation

As a national high-tech enterprise, Qinglong has established a full-process quality control system covering everything from raw material screening to finished product testing. In the Dongguan Women and Children's Activity Center project, optimized mix design and three-dimensional laser positioning installation kept the carbonation depth of the GRC decorative components to only 0.8mm over 5 years of service. The Technical Standard for Building Application of Glass Fiber Reinforced Cement (GRC) (JGJ/T423-2018), which the company helped develop, clearly specifies carbonation limits for GRC panels under different environmental categories, providing a technical specification for the industry.

Mastering the carbonation behavior of GRC panels requires a deep integration of materials science and engineering practice. Building on 28 years of industry experience, Qinglong Group continuously improves the carbonation resistance of its GRC products through material innovation and technical optimization. In the future, the development of ultra-high performance concrete (UHPC) and GRC composite technology will further expand the durability boundaries of architectural decoration materials, providing solid technical support for the corporate mission of "creating beautiful architecture".