Do Colored UHPC Exterior Walls Fade at Different Rates Across Climate Zones? Environment-Adaptive Design and Long-Term Color Retention Technology

The fading rate of colored UHPC exterior walls does indeed vary significantly across climate zones, with the main driving factors being solar radiation intensity (especially ultraviolet rays), the concentration of air pollutants (such as acid rain and salt fog), temperature, and humidity. Based on long-term tracking data from projects in different climate zones—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 maintain a color difference ΔE of ≤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 in inland areas. Scientific material selection and protective design are key to addressing these regional differences.

Ultraviolet radiation is the primary culprit of fading. In high-altitude, high-UV regions such as Tibet and Qinghai, highly weather-resistant inorganic pigments (such as iron oxide series with lightfastness grade 8) must be used, along with added UV absorbers (such as benzotriazoles). In its projects in such regions, Qinglong Group additionally applies a light-stabilizing coating containing nano-TiO2, 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 ion diffusion coefficient ≤2.0×10⁻¹²m²/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, drastic thermal expansion and contraction can easily cause micro-cracks 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 for China's major climate zones and can tailor color protection solutions for different projects. Through scientific approaches, colored UHPC can fully maintain its stunning colors over the long term in even the harshest environments.