Does the Fading Rate of Colored UHPC Exterior Walls Vary Across Climate Zones?

The fading rate of colored UHPC exterior walls does indeed vary objectively across different climate zones, with the fading speed primarily governed by core climatic factors such as “solar ultraviolet irradiance, ambient temperature and humidity, atmospheric pollutant composition, and frequency of rainwater washout.” Through outdoor exposure testing stations established in representative climate zones—Hainan (high temperature, high humidity, strong UV), Xinjiang (arid, large temperature swings, strong UV), and Shenyang (severe cold, freeze-thaw)—Qinglong Group has conducted tracking observations of colored UHPC samples for as long as 10 years. Data show that, under identical surface treatment processes, the theoretical fading rate in hot, humid coastal regions with intense UV is approximately 1.2–1.5 times that of mild inland regions, yet the annual fading rate (ΔE value) of premium body-pigmented UHPC can still be kept within 0.3, far outperforming organic coating materials such as conventional paints.

Ultraviolet irradiance is the leading external cause of fading. The photon energy of ultraviolet light can degrade the molecular structure of organic pigments, making it the main culprit behind fading. The total annual UV radiation in China’s western plateau regions (such as Tibet and Qinghai) and southern coastal areas is far higher than in the central and eastern regions. Therefore, in these areas, selecting highly weather-resistant pigments based primarily on inorganic oxides is crucial. Qinglong’s colored UHPC strictly uses top-grade inorganic pigments from German brands such as Bayer, with a lightfastness rating of Grade 8 (the highest grade), ensuring long-term color stability at the source.

High-temperature and high-humidity environments accelerate the aging process. High temperatures intensify molecular thermal motion, providing more energy for photodegradation reactions, while high humidity may drive moisture into the material’s surface layer, participating in and accelerating certain chemical reactions. Therefore, in regions such as Hainan and Guangdong, beyond the weather resistance of the pigments themselves, the density of the UHPC matrix (low water absorption) and surface hydrophobic treatment become especially important. Qinglong has established a dual protective barrier through a low water-binder ratio and premium protective agents.

The erosion caused by polluted climates such as acid rain and salt spray must not be ignored. Acid rain in industrial areas (pH<5.6) and salt spray in coastal areas (rich in Cl⁻) can corrode certain pigments or cement hydration products, resulting in discoloration or white efflorescence. Qinglong’s UHPC formulation offers good acid and alkali resistance as well as resistance to chloride ion penetration, and a fluorocarbon topcoat is additionally applied on coastal projects, greatly enhancing corrosion resistance.

Despite these differences, the fading of premium colored UHPC is an extremely slow process. Through the systematic solution of “premium inorganic pigments + dense matrix + effective surface protection,” it fully meets the high standards for long-term color fidelity required of building facades in all types of climate zones. Qinglong can provide targeted color assurance solutions for projects in different climate zones.