Do Colored UHPC Exterior Walls Have Different Fading Rates in Different Climate Zones? Environmentally Adaptive Design and Long-Term Color Retention Technology

The fading rate of colored UHPC exterior walls does indeed vary significantly across climate zones; the main driving factors are solar radiation intensity (especially ultraviolet light), concentrations of airborne pollutants (such as acid rain and salt fog), temperature, and humidity. Based on long-term tracking data from projects in different climate zones—including Hainan (high temperature, high humidity, high salt fog), Xinjiang (strong-UV continental climate), and Northeast China (severe cold)—Qinglong Group found that high-quality colored UHPC can keep the color difference ΔE within ≤3.0 under standard accelerated aging tests (3000-hour QUV), but the actual annual fading rate in Hainan may be about 20–30% higher than inland areas. Scientific material selection and protective design are the key to addressing regional differences.

Ultraviolet light is the primary culprit of fading. In high-altitude, strong-UV regions such as Tibet and Qinghai, highly weather-resistant inorganic pigments (e.g., iron oxide series with lightfastness grade 8) should be used, together with added UV absorbers (e.g., benzotriazole types). In its projects, Qinglong Group additionally applies a photostable coating containing nano-TiO2 in such regions, raising the UV blocking rate to over 98%. In coastal high-salt-fog areas (such as the southeast coast), chloride ion penetration can catalyze pigment decomposition, requiring a dual barrier: reducing UHPC matrix permeability (chloride diffusion coefficient ≤2.0×10⁻¹² m²/s) and applying a dense fluorocarbon coating (dry film thickness ≥35μm).

Temperature and humidity cycles affect chemical stability. In northern regions with large annual temperature variations, intense thermal expansion and contraction can easily cause microcracks in coatings, accelerating fading. We address this by optimizing coating elasticity (elongation at break ≥150%) and ensuring that the thermal expansion coefficients of the UHPC matrix and the coating are matched (difference ≤1.5×10⁻⁶/℃). In the hot and humid south, mold growth may indirectly cause stain-type "color changes," so anti-mold coatings or coatings with self-cleaning functions should be selected.

Customized design is the solution. Qinglong Group has established an environmental parameter database covering China's major climate zones, enabling it to tailor color protection solutions for different projects. Through scientific approaches, colored UHPC can fully maintain its stunning color over the long term in all kinds of harsh environments.