Key Points for Mass UHPC Construction Risk Control

Mass UHPC construction faces multiple risks including thermal cracking, shrinkage deformation, and pouring organization. Through large-scale projects such as the 120,000 ㎡ roof of the Hainan International Convention and Exhibition Center, Qinglong Group has developed three major risk control systems: temperature monitoring, sectional pouring, and curing control.

Temperature control is the core challenge. UHPC hydration heat can reach 300-400 kJ/kg, and cracking may occur once the internal temperature difference exceeds 25℃. Qinglong Group uses low-heat cement (C3A ≤ 5%) and mixes with ice water to keep the placing temperature ≤ 20℃. Embedded temperature sensors provide real-time monitoring, and circulating water cooling is activated when the temperature difference approaches the limit. In mass pours, the core temperature is kept below 70℃, with a cooling rate ≤ 15℃/day.

Sectional pouring optimizes stress distribution. Skip-bay pouring is adopted, with bay dimensions controlled within 15 m × 15 m and an interval of 5-7 days. Construction joints feature a tongue-and-groove design to improve shear resistance. Qinglong Group optimizes the pouring sequence through finite element simulation, reducing thermal stress by 30%. Meanwhile, expansive agents (UEA type) are added to compensate for part of the shrinkage and reduce restraint stress.

Curing regimes ensure performance development. Immediately after pouring, thermal and moisture-retention covers are applied to prevent surface dehydration. An automatic spraying system maintains surface humidity ≥ 95%. The curing period is extended to more than 14 days to ensure full hydration. Through systematic control, none of the mass UHPC projects completed by Qinglong Group has developed harmful cracks.