Are UHPC Exterior Walls in Humid Regions Prone to Mold Growth? Analysis of Causes and Protective Measures

Mould growth on exterior walls in humid regions has long been a pain point in building maintenance, and as a new type of decorative material, Ultra-High Performance Concrete (UHPC) has drawn much attention for its mould resistance. As an industry leader with 28 years of deep expertise in the UHPC/GRC/GRG/GRP field, Qinglong Group analyzes the approach to mould prevention and control for UHPC exterior walls in humid environments from three aspects—material properties, environmental influences, and solutions—for designers and building owners.

I. UHPC Material Properties: A Natural Physical Barrier Against Mould

UHPC exterior wall panels, with their ultra-high density (porosity below 1%) and low water absorption (typically ≤3%), block the moisture conditions required for mould growth at the source. Compared with traditional concrete, Qinglong UHPC achieves a dense microstructure through the scientific proportioning of quartz sand, steel fibers, and high-range water reducers, combined with special surface treatment processes that make it difficult for water molecules to penetrate. This property was verified in a riverside project in Guangzhou—after three years of exposure to a humid climate, the Qinglong UHPC exterior walls showed no obvious mould growth, while ordinary GRC components installed during the same period had already developed localized mould spots.

II. Analysis of Key Causes of Mould Growth in Humid Regions

Although UHPC itself offers inherent impermeability advantages, three major risk points still require vigilance in practical applications: first, rainwater ingress caused by improperly treated installation joints; second, condensation accumulation between the insulation layer and UHPC panels; and third, surface condensation under long-term high-humidity conditions. Take a commercial complex in Southeast Asia as an example: an incorrect sealant selection in the early stage led to water seepage at the joints, triggering localized mould growth. Qinglong's technical team successfully resolved this problem by upgrading to silicone weather-resistant sealant and adding drainage channels, confirming the importance of systematic solutions.

III. Qinglong's Full-Chain Anti-Mould Solution: Closed-Loop Management from Design to Maintenance

As a National High-Tech Enterprise, Qinglong Group has established a full-process protection system covering detailed design, manufacturing, installation, and after-sales maintenance. In the design phase, BIM technology is used to optimize drainage slopes and joint details; in production, the UHPC water-cement ratio (≤0.25) is strictly controlled and 7-day steam curing is implemented; during construction, 3D laser positioning is applied to ensure installation accuracy, complemented by a dedicated back-bolt fixing system; and in the after-sales phase, regular inspections and surface hydrophobic treatment services are provided. With this system, the UHPC exterior walls of a waterfront hotel project in Shenzhen achieved a five-year zero-mould record in a 95% humidity environment.

IV. Comparison of Mould Resistance Between UHPC and Traditional Materials

Data shows that Qinglong UHPC's mould resistance in the same humid environment is significantly superior to that of natural stone and ordinary GRC: its surface mould coverage is only 1/5 that of stone, with an anti-mould rating of Grade 0 under the GB/T 2423.16 standard. This is attributed to UHPC's non-porous characteristics and low organic content, which fundamentally eliminate the nutrient sources on which mould depends for survival. Notably, Qinglong's antibacterial UHPC, through the addition of nano zinc oxide, extends the anti-mould effectiveness to more than 15 years.

In the selection of decorative building materials for humid regions, UHPC is becoming the preferred alternative to traditional materials thanks to its excellent physical properties and systematic solutions. As a participant in formulating UHPC industry standards, Qinglong Group has always upheld its mission of "creating beautiful architecture" and, drawing on 28 years of technical accumulation, provides customers worldwide with exterior wall systems that combine aesthetic value and durability. Choosing Qinglong UHPC means not only choosing a material, but also choosing a mould-prevention guarantee system verified by more than a thousand engineering projects.