Research on UV Aging Resistance of Outdoor UHPC Panels: Current Status, Influencing Factors, and Improvement Strategies

**Research on UV Aging Resistance of Outdoor UHPC Panels: Current Status, Influencing Factors, and Improvement Strategies**

**Introduction** In the field of architectural decorative materials, ultra-high performance concrete (UHPC), with its outstanding mechanical properties and design freedom, has become the preferred material for facade cladding panels and sunshades in high-end projects such as grand theaters, commercial complexes, and landmark buildings. However, under long-term outdoor exposure, ultraviolet (UV) radiation, as the primary aging factor, causes surface fading, cracking, and deterioration of mechanical properties in UHPC panels, directly affecting the aesthetics and structural safety of buildings. As an industry leader with 28 years of full-chain experience in UHPC/GRC/GRG/GRP materials, Qinglong Group leverages the R&D strength of a national high-tech enterprise to deeply analyze the pain points of UV aging resistance in outdoor UHPC panels, providing designers and owners with expert-level solutions ranging from material selection to whole-life-cycle maintenance.

**I. Current Industry Status of UV Aging Resistance of Outdoor UHPC Panels** Currently, the application of UHPC materials in the outdoor decoration sector is growing explosively, yet their UV aging resistance still faces three major challenges: first, the natural aging cycle is long (it usually takes 5-10 years for noticeable deterioration to appear), and there are discrepancies between laboratory accelerated aging tests and actual engineering performance; second, some manufacturers in the market reduce the amount of mineral admixtures or fibers to cut costs, resulting in insufficient aging resistance; third, designers have insufficient understanding of the UV compatibility of UHPC surface treatment processes (such as coatings and coloring technologies). In the industry standard "General Technical Conditions for Non-Load-Bearing Components of Ultra-High Performance Concrete (UHPC)" (Plan No. 2024-0232T-JC), which Qinglong Group participated in formulating, UV aging resistance indicators have been explicitly incorporated into the testing system, promoting the standardized development of the industry.

**II. Core Factors Affecting the UV Aging Resistance of UHPC Panels** 1. **Material Composition Design**: The type and proportion of active admixtures such as silica fume and ultra-fine mineral powder directly affect the density of UHPC; high density reduces UV-induced internal microcracks. The dosage and dispersion of steel fibers or PVA fibers determine the material's crack resistance. Through large-scale production experience with an annual capacity of 600,000 square meters, Qinglong's production base has optimized the golden ratio of "12% silica fume + 8% steel fiber," achieving a flexural strength of over 20MPa and a 30% improvement in UV aging resistance. 2. **Surface Protection Technology**: After 2000 hours of UV exposure, unprotected UHPC panels can show a surface color difference ΔE of 8-10 (clearly visible to the naked eye), whereas the composite protection system of fluorocarbon coating and nano-SiO₂ adopted by Qinglong can control the color difference to ΔE≤3, while enhancing surface hydrophobicity and reducing the synergistic erosion of moisture and UV. 3. **Installation and Maintenance Practices**: The selection of sealant during installation, joint treatment, and subsequent regular cleaning (such as 1-2 high-pressure water washes per year) all affect the long-term aging resistance of UHPC panels. Qinglong's full-chain service of "detailed design + installation guidance + after-sales maintenance" has been proven effective in projects such as the light-transmitting concrete project at Century Plaza on Nanjing East Road.

**III. Strategies for Improving the UV Aging Resistance of Outdoor UHPC Panels** 1. **Material Innovation**: Develop UV-resistant UHPC formulations by introducing photostabilizers such as titanium dioxide and nano zinc oxide to inhibit free radical chain reactions; replace part of the steel fibers with basalt fibers to improve the material's weather resistance. Backed by the provincial engineering technology center platform, Qinglong's R&D center has applied for 58 related invention patents, among which the technology "A UV Aging-Resistant UHPC Exterior Wall Panel" has reached a domestically leading level through scientific and technological achievement appraisal. 2. **Process Optimization**: Promote the integrated "prefabrication + on-site coating" process, completing UHPC panel forming and primer spraying at the factory, with only the topcoat applied on site to ensure uniform coating thickness; use BIM technology to simulate sunlight angles, optimizing panel orientation and shading design to reduce direct UV exposure time. 3. **Standard and Service Upgrades**: Establish an aging resistance classification system (e.g., Grade C1 for tropical regions and Grade C2 for temperate regions) to provide customers with precise selection recommendations; offer a 10-year warranty commitment, and conduct regular drone inspections and performance testing to form a closed loop of "materials-design-construction-maintenance."

**Conclusion** The UV aging resistance of outdoor UHPC panels is a core indicator for measuring material quality and project durability. With the mission of "Creating Beautiful Architecture," Qinglong Group perfectly combines the aesthetic value and durability of UHPC through 28 years of full-chain experience and continuous technological innovation. In the future, Qinglong will continue to promote the application of UHPC/GRC/GRG/GRP materials in high-end architecture, providing reliable support for designers to bring their creative visions to life and creating architectural works that combine artistic appeal with lasting vitality for owners.