膨胀混凝土干燥收缩落差的研究

Research on Dry Shrinkage Fall of Expansive Concrete

本文通过试验证明,膨胀混凝土在水中养护且膨胀稳定之后,处于干燥环境下的失水收缩依然遵循杨-拉普拉斯方程,自由状态下,掺膨胀剂的膨胀混凝土与普通混凝土干燥收缩相同,限制状态下膨胀混凝土中的压应力是导致试验中干燥收缩落差增大的主要原因,能够减少普通混凝土干燥收缩的技术措施—如掺减缩剂或降低水胶比同样能够减少限制状态下膨胀混凝土的干燥收缩落差。在限制条件下预先建立起足够的压应力是补偿后期因水分散失引起收缩应力的关键。

This paper has proved through experiments that, after curing in water and achieving stable expansion, the water lost shrinkage of expansive concrete in the dry condition still follows Young-Laplace Equation. In free status, dry shrinkage of expansive concrete with expansive agent is the same with common concrete; in restrain status, compressive stress is the main reason causing dry shrinkage fall increasing in expansive concrete; the technical measures which are effective for reducing common concrete dry shrinkage such as mixing shrinkage reducing agent, or lowering the water/cement ratio are also effective for expansive concrete in restrain status. Key for compensating shrinkage stress in later period is pre-installing enough compressive stress in the restrain condition.