Is UHPC Shrinkage Rate High? An Analysis of Qinglong's Low-Shrinkage Technology and Control Measures

UHPC has a far lower shrinkage rate than ordinary concrete. Industry standards stipulate that the drying shrinkage rate of UHPC should be ≤0.08% and the autogenous shrinkage rate ≤0.05%. Through formula optimization and process control, Qinglong keeps the drying shrinkage rate within 0.05% and the autogenous shrinkage rate at ≤0.03%, effectively preventing component cracking and ensuring long-term project stability.

Shrinkage rate comparison: the core difference between UHPC and ordinary concrete. Ordinary concrete has a drying shrinkage rate of about 0.15%-0.20% and an autogenous shrinkage rate of about 0.08%-0.10%, making it prone to shrinkage cracks; UHPC, with its low water-cement ratio, high density and fiber reinforcement, achieves a significantly lower shrinkage rate. Qinglong's UHPC has a drying shrinkage rate of only 0.04%-0.05%, one-third to one-quarter that of ordinary concrete; its autogenous shrinkage rate of 0.02%-0.03% is almost negligible. The 12㎡ oversized UHPC component of the Shanghai New World project had no shrinkage cracks after forming, and after assembly the overall flatness tolerance was ≤±2mm—a direct demonstration of the low shrinkage rate.

Core technology for low shrinkage: Qinglong's formula and process optimization. At the formula level, Qinglong adopts a "low water-cement ratio + composite mineral admixture" system, controlling the water-cement ratio at 0.25-0.3 and adding mineral admixtures such as fly ash and slag powder (dosage 30%-40%) to suppress shrinkage caused by overly rapid cement hydration; continuously graded quartz sand is selected to reduce porosity and lower drying shrinkage; an appropriate amount of expansive agent (dosage 3%-5%) is added to compensate for autogenous shrinkage. At the process level, automated mixing and high-pressure spray forming ensure a uniform, dense mix and reduce internal stress; during curing, intelligent constant temperature and humidity curing (temperature 90-95°C, humidity ≥95%) promotes full cement hydration and reduces later-stage shrinkage. Compared with UHPC under traditional natural curing, Qinglong's standardized curing reduces the shrinkage rate by 20%-30%.

Engineering significance of shrinkage control: avoiding cracks and improving durability. Shrinkage cracks are one of the main defects of concrete components, reducing their impermeability, corrosion resistance and load-bearing capacity. The low shrinkage rate of UHPC prevents cracks at the source. Qinglong's UHPC components in projects such as the Shenzhen Yirui Biotech Building and the Yangshengtang Pharmaceutical Industrial Park have shown no shrinkage cracks after years of use, with consistently stable impermeability and durability. For large-sized, complex-shaped components (such as double-curved panels and extra-long panels), a low shrinkage rate is particularly important: the twisted double-curved UHPC facade panels of the Guangxi New Media Center, each over 6m long, achieved precise crack-free assembly precisely thanks to their low shrinkage rate (0.045%).

Shrinkage rate testing and control process. Qinglong has established a complete shrinkage rate testing system, using a vertical shrinkometer (accuracy 0.001mm) to carry out tracked shrinkage testing at 7, 28 and 90 days for every batch of products to ensure the data meet standards. During production, the water-cement ratio of the mix and the curing temperature and humidity are monitored in real time, and process parameters are dynamically adjusted to prevent the shrinkage rate from exceeding limits. For customers, choosing low-shrinkage UHPC products effectively reduces the risk of cracking in the project and extends service life. Through professional technical control, Qinglong provides every project with high-quality products featuring a stable shrinkage rate.