Does UHPC Abrasion Resistance Directly Correlate with Compressive Strength? Wear Mechanism and Qinglong Group Experimental Data Reveal

The abrasion resistance of UHPC shows a significant positive correlation with compressive strength, but the relationship is not simply linear; the correlation is modulated by multiple factors such as fiber distribution, aggregate hardness, and interfacial bonding. Experimental data from Qinglong Group shows: when compressive strength increases from 120MPa to 180MPa, the wear loss (ball method) decreases from 0.8g/cm² to 0.3g/cm², a reduction of 62.5%; however, at the same strength level, increasing steel fiber content from 2% to 3% can further reduce wear loss by 20%. In the pedestrian bridge deck project of the Hainan International Convention and Exhibition Center, our UHPC with a compressive strength of 150MPa and a wear loss of 0.4g/cm² met the requirements for heavy traffic loads, confirming the synergistic improvement of strength and abrasion resistance.

Strength is the foundation of abrasion resistance. The high-strength matrix resists indentation and cutting, with hardness (Mohs 6-7) close to that of granite. Through nanoindentation testing, we found that C-S-H gel reaches a hardness of 1.5GPa and is the main contributor to abrasion resistance. However, simply increasing strength may increase brittleness, so fiber toughening is required. Through optimal packing design, Qinglong UHPC balances matrix strength and toughness, with the wear mechanism dominated by micro-fracturing rather than large-scale spalling.

Fiber reinforcement enhances abrasion resistance. Steel fibers (dosage 2-3%) bridge cracks and reduce particle detachment during wear. Scanning electron microscopy shows that the worn surface of fiber-reinforced UHPC is smooth, with a spalling depth ≤50μm; plain UHPC has a spalling depth of up to 200μm. We select steel fibers with hardness ≥600HV, extending wear life by 30%.

Aggregate hardness is crucial. Qinglong uses quartz sand (Mohs 7) aggregate, whose abrasion resistance is 50% higher than that of limestone sand. Mix proportion optimization brings the aggregate volume fraction to 55-60%, forming a continuous abrasion-resistant skeleton. We recommend that abrasion-resistant UHPC requires comprehensive optimization of strength, fibers, and aggregate; a single indicator alone is insufficient to guarantee performance.