What Factors Affect the Carbonation Rate of GRC Panels? Durability Improvement Solutions

The carbonation rate of GRC panels is mainly related to three major factors: "material composition, environmental conditions, and production processes." Carbonation causes surface strength to decline. High-quality GRC panels should keep the annual carbonation depth at ≤0.5mm. Through formula optimization and process upgrades, Qinglong has kept the 20-year carbonation depth of its products at ≤10mm; projects such as Panzhihua in Sichuan and Dali University in Yunnan have all achieved long-term durability.

I. Material Composition: The Core Internal Factor Affecting Carbonation

Material composition determines carbonation resistance. Cement type: low-alkali cement (alkali content ≤0.6%) has a carbonation rate 30% slower than ordinary cement. Qinglong selects low-alkali sulphoaluminate cement to reduce Ca(OH)₂ content and delay carbonation. Mineral admixtures: adding 15-20% silica fume or mineral powder fills internal pores and reduces the CO₂ penetration rate. Qinglong's silica fume content is 18%, and the compactness of its GRC panels is ≥2.2g/cm³. Fiber type: alkali-resistant glass fibers resist carbonation attack better than ordinary fibers. Qinglong's fibers have an alkali resistance retention rate of ≥90% and still maintain their reinforcing effect after carbonation. Water-cement ratio: controlled at 0.45-0.5; an excessively high water-cement ratio increases porosity. Qinglong's automated batching system precisely controls the water-cement ratio with an error of ≤±0.02.

II. Environmental Conditions: External Factors That Accelerate or Delay Carbonation

Environmental conditions directly affect the carbonation rate. Humidity: carbonation is fastest at an ambient humidity of 50-70%, while humidity that is too high (>80%) or too low (<30%) slows it down. Qinglong customizes anti-carbonation formulas for coastal high-humidity projects (such as Sanya Festival Plaza), with silane impregnation agents applied to the surface. CO₂ concentration: CO₂ concentration is high in city centers and industrial areas, where the carbonation rate is 2 times faster than in suburban areas. Qinglong increases the protective layer thickness by 3-5mm for industrial plant projects. Temperature: rising temperatures accelerate the carbonation reaction. High-temperature regions (such as Panzhihua in Sichuan) require heat-resistant cement. The GRC panels of Qinglong's Panzhihua project have an annual carbonation depth of ≤0.4mm under high temperatures. Freeze-thaw cycles: repeated freeze-thaw cycles damage the surface structure and accelerate carbonation. The GRC panels of Qinglong's northern projects withstand ≥300 freeze-thaw cycles with no significant increase in the carbonation rate.

III. Production Processes and Qinglong's Durability Assurance

Process optimization improves carbonation resistance. Forming process: high-pressure vibration (pressure ≥0.5MPa) reduces internal pores. Qinglong's high-pressure vibration keeps porosity at ≤15%, making CO₂ penetration more difficult. Curing process: constant temperature and humidity curing (14 days) ensures full hydration and forms dense hydration products on the surface. The temperature and humidity precision of Qinglong's curing rooms is ±1℃, improving carbonation resistance by 25%. Surface protection: applying fluorocarbon coatings or silane impregnation agents forms a protective barrier. For the GRC panels of the Library and Information Center at Dali University in Yunnan, Qinglong reduced the carbonation rate by 40% after applying silane impregnation agents. Project case: for the Third Front Construction Cultural Tourism Project in Panzhihua, Sichuan, Qinglong's GRC panels have been in use for 8 years in a high-temperature, dry environment, with a carbonation depth of only 4mm, far below the industry average, and a strength retention rate of ≥95%.