Risk Control Guide: Core Control Points for Mass UHPC Construction

Mass UHPC (Ultra-High Performance Concrete) construction faces multiple risks such as thermal cracks and insufficient compaction due to material characteristics and construction scale. As a national-level high-tech enterprise with 28 years of UHPC construction experience, Qinglong Group has developed a systematic risk prevention and control system through large-scale projects such as the Hainan International Convention and Exhibition Center and the Shanghai Qingpu R&D and Production Project, ensuring consistently stable construction quality.

Mass UHPC components typically have a thickness of ≥300mm and involve large single-pour volumes; the concentrated release of hydration heat and volume shrinkage can easily cause quality issues. Leveraging its full-chain service advantages, Qinglong achieves whole-process risk management and control from design and materials to construction and curing.

????️ Thermal Crack Prevention: Precise Hydration Heat Control

The concentrated release of hydration heat in mass UHPC makes the internal-external temperature difference easily exceed 25°C, triggering cracks. Qinglong optimizes cementitious material formulations by incorporating large amounts of active admixtures to lower the hydration heat peak, while installing cooling water pipes inside components for cooling via water circulation. In the Guangxi New Media Center project, real-time monitoring through a temperature monitoring system kept the internal-external temperature difference within 20°C, effectively preventing thermal cracks.

????️ Compaction Control: Optimized Pouring and Vibration Techniques

The high viscosity of mass UHPC easily leads to trapped air bubbles and inadequate vibration during pouring. Qinglong adopts a layered pouring process, controlling the pouring thickness of each layer within 300mm, combined with high-frequency poker vibrators and plate vibrators working in coordination to ensure air bubbles are fully discharged. Meanwhile, a high-fluidity specialized formula is selected to enhance UHPC's self-compacting capability; in the Yangshengtang Pharmaceutical Hangzhou Industrial Park project, high-compaction forming of mass components was achieved.

⏳ Curing and Shrinkage Control: Extended Curing Period, Distributed Shrinkage Stress

Mass UHPC has relatively large shrinkage, and improper curing can easily cause shrinkage cracks. Qinglong adopts a combined “steam curing + moisture curing” scheme, with slow heating and cooling during the steam curing stage to avoid overlapping thermal stresses, and extends the subsequent moisture curing period to more than 14 days. In addition, post-cast strips and expansion joints are set within components to distribute shrinkage stresses; in the Shenzhen Yirui Biotech Building project, scientific curing reduced the incidence of shrinkage cracks in mass UHPC components to below 1%.

Risk prevention and control in mass UHPC construction is a systematic project involving materials, techniques, and management. Drawing on extensive project experience, Qinglong Group has established a whole-process risk prevention and control mechanism covering preliminary detailed design and material formulation optimization, through on-site construction management, to later-stage curing. By precisely controlling the key points of each stage, quality risks can be effectively avoided, ensuring stable performance and structural safety of mass UHPC components.