How to Set Steam Curing Parameters for Precast UHPC Components: A Study on Key Influencing Factors and Optimization Strategies

How to Set Steam Curing Parameters for Precast UHPC Components: Key Influencing Factors and Optimization Strategies

In the field of building materials, UHPC (Ultra-High Performance Concrete) has become an ideal choice for modern architectural decoration thanks to its outstanding mechanical properties and durability. However, the quality of precast UHPC components largely depends on the parameter settings of the steam curing process. As an industry leader with 28 years of experience in detailed design, production and manufacturing of UHPC/GRC/GRG/GRP materials, Qinglong Group fully understands the decisive role that scientific and rational steam curing plays in component performance. This article analyzes optimization strategies for the steam curing parameters of precast UHPC components from three dimensions—temperature, humidity, and time—providing a professional reference for the industry.

1. Steam Curing Temperature: Balancing Strength Development and Microstructure

Temperature is the core factor affecting the hydration reaction rate of UHPC. In the production of precast UHPC components, the curing temperature is typically controlled between 40°C and 80°C. Too low a temperature slows the hydration reaction and prolongs the curing cycle, while too high a temperature may cause the internal temperature to rise too quickly, generating thermal stress that leads to microcracks. Through 28 years of engineering practice, Qinglong Group has found that a “staged heating” model can effectively resolve this contradiction: in the initial stage (0–2 hours), the temperature rises to 50°C at a rate of 10°C per hour; in the middle stage (2–6 hours), a constant temperature of 60°C is maintained; and in the final stage (6–10 hours), the temperature is slowly lowered back to room temperature. This gradient temperature control both promotes full cement hydration and avoids thermal damage. Testing shows that UHPC components produced with this process achieve a 15%–20% increase in 28-day compressive strength.

2. Humidity Control: Safeguarding the Hydration Environment and Surface Quality

The humidity parameters of steam curing directly affect the surface integrity and internal density of UHPC components. Practice at Qinglong Group's production base in Nanning, Guangxi shows that relative humidity must be maintained above 90% while avoiding localized condensation. Traditional open curing often causes surface “sand dusting” on components due to uneven humidity distribution, whereas the “enclosed steam circulation system” adopted by Qinglong can achieve a humidity deviation of ≤5%. Combined with an automatic mist humidification device, this raises component surface flatness to within 0.5mm/m. Notably, for the curved and irregular surfaces of UHPC decorative components, BIM technology should be used to simulate moisture evaporation paths, and moisture-conducting channels should be pre-set at the mold design stage to ensure uniform humidity at complex shapes.

3. Curing Time: Dynamic Adjustment to Match Project Requirements

The setting of curing time must balance production efficiency with performance requirements. Qinglong Group has established differentiated time standards for different project types: precast components for municipal engineering adopt “72-hour standard curing,” of which steam curing accounts for 48 hours, while UHPC facade panels for landmark buildings are extended to 96 hours, with emphasis on strengthening the final 24 hours of low-temperature curing (40°C ± 5°C) to promote full formation of CSH gel. Comparative testing shows that this process can increase the elastic modulus of components by 12% and achieve an impermeability rating of P12 or above. In addition, the “curing time–strength prediction model” developed by Qinglong can automatically generate the optimal curing curve based on raw material mix proportions, shortening the trial mixing cycle by 30%.

4. Full-Chain Coordination: Qinglong's Innovative Curing Technology Practices

As a national high-tech enterprise, Qinglong Group integrates the steam curing process with detailed design and construction installation into closed-loop management. For example, in the renovation project of Century Plaza on Nanjing East Road, to meet the curing requirements of light-transmitting UHPC components, an innovative “infrared temperature measurement + intelligent temperature control” system was adopted to monitor the internal temperature field of components in real time, ensuring a light transmittance deviation of ≤3%. This full-chain service capability has given Qinglong unique advantages in the field of UHPC/GRC/GRG/GRP materials, and it has participated in the formulation of industry standards such as the “General Technical Conditions for Non-Load-Bearing Ultra-High Performance Concrete (UHPC) Components.”

Steam curing is the “lifeline” of quality control for precast UHPC components, and its parameter settings must be scientifically optimized based on material characteristics, component geometry, and engineering requirements. Qinglong Group's 28 years of industry experience show that by precisely controlling the three key factors of temperature, humidity, and time, combined with digital management tools, a perfect balance between UHPC component performance and production efficiency can be achieved. Looking ahead, in line with the trend of green building development, Qinglong will continue to explore low-carbon curing technologies, contributing to the innovative application of UHPC materials in architectural decoration.