By how many orders of magnitude does UHPC's impermeability exceed that of ordinary C80 concrete?

The impermeability of UHPC is an important manifestation of its exceptional durability, offering advantages of orders of magnitude over ordinary concrete. Test data from Qinglong Group shows that the impermeability of high-quality UHPC can be 2-3 orders of magnitude higher than that of C80 high-performance concrete.

The chloride ion diffusion coefficient is a key indicator for evaluating impermeability. The chloride ion diffusion coefficient of C80 concrete is typically on the order of 1×10⁻¹²m²/s, while high-quality UHPC can reach below 1×10⁻¹⁵m²/s—a difference of three orders of magnitude. The UHPC roof panels used by Qinglong Group in the Hainan International Convention and Exhibition Center project achieved a measured chloride ion diffusion coefficient of 0.8×10⁻¹⁵m²/s, significantly improving durability in marine environments.

The comparison in water impermeability is equally significant. According to tests under the GB/T 50082 standard, the impermeability grade of C80 concrete is typically P8-P10, while UHPC can reach above P20. Qinglong Group's test data shows that its UHPC products withstand 1.2MPa water pressure for 24 hours without seepage, delivering more than twice the impermeability of C80 concrete.

Gas impermeability is another important point of difference. The diffusion coefficient of carbon dioxide in UHPC is two orders of magnitude lower than in C80 concrete, which means the carbonation rate is greatly slowed. Qinglong Group's long-term tracking data shows that the annual carbonation depth of UHPC components is less than 0.01mm, with a predicted 50-year carbonation depth of less than 0.5mm. This order-of-magnitude advantage in impermeability directly translates into a significant improvement in durability.