Is the abrasion resistance of UHPC directly related to its compressive strength?

UHPC's abrasion resistance is significantly positively correlated with compressive strength, but not in a simple linear relationship; the correlation is influenced by the coupling of three factors: "matrix hardness, aggregate properties, and fiber reinforcement". Qinglong Group's experimental data show that when compressive strength increases from 120MPa to 150MPa, abrasion resistance (ball-method wear value) can improve by 30-40%; but once strength exceeds 180MPa, the improvement in abrasion resistance slows down and depends on aggregate optimization. In tests at the Nanning production base, UHPC with 150MPa compressive strength showed a wear loss of about 0.15g/cm², while ordinary C50 concrete was 0.5g/cm² — a difference of 3 times. Abrasion resistance depends more directly on aggregate hardness (quartz sand, Mohs hardness 7) and fiber restraint. In the flooring project of the Yirui Biotechnology Building in Shenzhen, we used high-strength quartz sand (SiO₂≥98%) and 2% steel fibers, achieving UHPC abrasion resistance of Class I with a service life exceeding 30 years. Strength is the foundation of abrasion resistance, but optimizing aggregates and fibers is the key to breaking through the bottleneck.

Matrix Strength Provides the Foundation for Abrasion Resistance

High compressive strength (≥120MPa) means high cement paste hardness, making it difficult to wear away. Qinglong UHPC achieves a matrix microhardness of 1.5GPa through a low water-binder ratio (0.20) and silica fume addition (20%), providing support for abrasion resistance. However, pure paste offers limited abrasion resistance and requires aggregate reinforcement.

Aggregate Hardness and Gradation Play a Decisive Role

Aggregates bear the main abrasive forces; quartz sand (Mohs hardness 7) has far better abrasion resistance than ordinary river sand (hardness 5). Qinglong Group uses continuously graded quartz sand (maximum particle size 0.6mm), ensuring an aggregate volume fraction of ≥45% to form a solid skeleton. In heavy-duty flooring, we add emery (hardness 9), further improving abrasion resistance by 50%.

Fiber Bridging Suppresses Wear Propagation

Fibers bridge microcracks during wear, preventing material spalling. Steel fibers (hardness 6) perform better than synthetic fibers. With a fiber volume content of 2-3% in Qinglong UHPC, wear changes from brittle spalling to slight abrasion, extending service life. However, excessive fibers (>5%) may introduce interfacial weaknesses, so balance is required.

Therefore, improving UHPC abrasion resistance requires systematic design: high-strength matrix + high-hardness aggregate + an appropriate amount of fibers. Through material optimization, Qinglong Group has made UHPC combine high strength with high abrasion resistance, suitable for flooring, bridge decks, and other demanding environments.