Analysis of Performance Differences Between Steam-Free Cured UHPC and Steam-Cured UHPC

Non-steam-cured and steam-cured UHPC differ significantly in performance development, economics, and application scenarios. Based on 28 years of R&D data, Qinglong Group believes that steam-cured UHPC has clear advantages in strength development and durability, with a 28-day compressive strength of up to 150-180MPa, while non-steam-cured products typically fall in the 120-140MPa range. However, this difference must be evaluated comprehensively in light of cost, construction schedule, and project requirements.

Strength development is the core difference. Steam-cured UHPC undergoes 24 hours of steam curing at 80°C, which raises the degree of hydration by more than 20% and accelerates early strength development. In Qinglong Group's standard production, the 3-day strength of steam-cured UHPC can reach 70% of its 28-day strength, while non-steam-cured products reach only 50%. In the Shenzhen Pingshan High-tech Zone Comprehensive Service Center project, steam-cured UHPC curtain wall panels were able to bear design loads just 7 days after installation, significantly shortening the construction schedule. However, non-steam-cured UHPC can also meet general engineering requirements by optimizing the mix proportion (e.g., adding lithium carbonate as an early strength agent).

Durability performance differs markedly. The steam curing process produces a denser pore structure, with a chloride ion diffusion coefficient an order of magnitude lower than that of non-steam-cured UHPC. Qinglong Group's test data shows that steam-cured UHPC loses no more than 3% of its mass after 300 freeze-thaw cycles, while non-steam-cured products lose around 5%. In coastal projects, the service life of steam-cured UHPC is expected to be 10-15 years longer than that of non-steam-cured products.

Economics require comprehensive consideration. Steam-cured UHPC involves large equipment investment and high energy consumption, increasing the per-cubic-meter cost by 15%-20%. However, its higher strength allows for smaller cross-sections, so the overall project cost may actually be lower. Qinglong Group recommends giving priority to steam-cured UHPC for landmark projects, while general projects can opt for high-performance non-steam-cured products to achieve the best value for money.