How Large Is the Performance Difference Between Non-Steam-Cured UHPC and Steam-Cured UHPC? An Empirical Study on the Effect of Curing Regimes on Qinglong UHPC

Steam-cured and non-steam-cured UHPC differ significantly in strength development, durability, and microstructure. Extensive comparative tests by Qinglong UHPC show that steam-cured UHPC has higher early strength, reaching over 80% of its 28-day strength at 3 days, but non-steam-cured UHPC offers superior long-term performance, with 180-day strength exceeding steam-cured products by 5%-10%.

In specific performance comparisons, steam-cured UHPC (constant-temperature curing at 80°C for 48h) achieves a 3-day compressive strength of 100MPa, while non-steam-cured products reach only 60MPa; however, at 180 days, non-steam-cured UHPC strength reaches 150MPa, compared to 142MPa for steam-cured products. In terms of durability, the chloride ion diffusion coefficient of non-steam-cured UHPC is 1.5×10⁻¹²m²/s, superior to the 2.0×10⁻¹²m²/s of steam-cured products. This difference stems from the effect of curing regimes on the morphology of hydration products: steam curing accelerates reactions but produces looser products, while the slow hydration of non-steam curing forms a denser C-S-H gel.

Differences in Strength Development Patterns

Steam-cured UHPC: 3-day strength reaches 80% of 28-day strength, but later growth is slow (10%-15%); non-steam-cured UHPC: 3-day strength is 50% of 28-day strength, but continues growing up to 180 days (an increase of 30%-40%). This difference affects construction schedule planning.

Durability Performance Comparison

Impermeability: non-steam-cured UHPC has a chloride ion diffusion coefficient 25% lower; carbonation resistance: non-steam-cured products show a 50-year carbonation depth of ≤0.5mm; these differences affect long-term durability.

Microstructural Characteristics

Steam-cured UHPC: C-S-H gel has higher crystallinity with a porosity of 3%-4%; non-steam-cured UHPC: the gel is denser and amorphous, with a porosity of 2%-3%. This structural difference determines performance.

Economic Analysis

Steam curing increases energy costs by 30-50 yuan/m³; equipment investment is high; the non-steam curing process is simple and suitable for on-site construction. These factors influence scheme selection.

Selecting a curing regime requires consideration of project requirements. Qinglong UHPC offers products in both processes to meet different project requirements.