Effect of external expansive agent addition on the strength and shrinkage deformation of UHPC

This study explored the dosage-dependent influence of two types of external expansive agents on the strength, early-age autogenous shrinkage, and drying shrinkage deformation of ultra-high-performance concrete (UHPC). By analyzing the impact of expansive agents on the microstructure of UHPC, the mechanisms through which different expansive agents affect the aforementioned factors were identified. The results showed that as the dosage of expansive agents increased, the compressive strength of UHPC at 28 days tended to improve. Notably, the expansive agent SY-G demonstrated a more pronounced strength enhancement effect than the expansive agent FQY. Moreover, the early-age autogenous shrinkage rate and drying shrinkage rate of UHPC were closely related to the type of expansive agent applied and its dosage. The intrinsic hydration behavior of SY-G and FQY, as well as their regulation of the cement hydration process, emerged as the key factors influencing the mechanical strength and shrinkage deformation of UHPC. Thus, to mitigate the early-age autogenous shrinkage and drying shrinkage of UHPC through expansive agent addition, optimized SY-G and FQY dosages of 10% and 8%, respectively, are recommended.