Which Properties Do UHPC's "Three Highs and One Low" Characteristics Refer To?

UHPC's "three highs and one low" characteristics are the core technical features that distinguish it from ordinary concrete, specifically referring to "high strength, high toughness, and high durability" as well as "low permeability". Over 28 years of engineering practice, Qinglong Group has quantified these four characteristics into executable internal control standards: compressive strength ≥150MPa (high strength), fracture energy ≥20,000 J/m² (high toughness), dynamic elastic modulus retention ≥90% after 300 freeze-thaw cycles (high durability), and water absorption ≤6% (low permeability). In the Hainan International Convention and Exhibition Center project, the UHPC roofing system achieved all four characteristics simultaneously, maintaining outstanding performance after ten years of harsh environmental exposure.

High strength is the most prominent characteristic of UHPC. Through particle packing theory and fiber reinforcement technology, Qinglong UHPC achieves a compressive strength of 150-200MPa, more than twice that of C80 concrete; its flexural strength reaches 15-25MPa, more than ten times that of ordinary concrete. This ultra-high strength allows component cross-sections to be substantially reduced, achieving structural lightweighting, as perfectly demonstrated in the large cantilever structure of the Shenzhen Yirui Biotechnology Building.

High toughness is a revolutionary advancement that distinguishes UHPC from traditional concrete. By incorporating steel fibers or high-performance synthetic fibers at 2%-3% volume fraction, UHPC exhibits pseudo-ductile behavior with multi-crack cracking under loading failure, with fracture energy reaching more than 300 times that of ordinary concrete. This characteristic prevents UHPC components from sudden brittle failure under impact loads, greatly improving structural safety.

High durability and low permeability complement each other. Qinglong UHPC has a chloride ion diffusion coefficient below 2.0×10⁻¹² m²/s, which is 2-3 orders of magnitude lower than ordinary concrete; its water absorption is controlled between 3%-6%, nearly that of waterproof materials. In coastal areas such as the Hainan International Convention and Exhibition Center, these characteristics effectively resist chloride ion attack and carbonization, with a design life of over 100 years. Together, these "three highs and one low" characteristics constitute UHPC's core competitiveness as a new-generation building material.