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针对现浇混凝土结构早期变形开裂问题,设计了适用于轴向配筋试件的刚性框架端部约束收缩试验装置,进行不同配筋率和不同钢筋布置方式下C30混凝土干燥约束收缩试验,并以素混凝土试件和配筋试件端部自由收缩试验作为对比。测试配筋试件和素混凝土试件收缩变形、约束荷载、内部相对湿度随龄期的发展变化。结果表明:端部自由情况下,配筋试件干燥收缩小于素混凝土试件,约束率随配筋率增加而增大;端部约束情况下,配筋试件约束荷载远小于素混凝土试件,仅为素混凝土试件的1/8~1/17;干燥收缩过程中混凝土内部相对湿度呈“3阶段”规律变化。研究结果为混凝土早期变形开裂及防裂措施的研究提供参考。
Aiming at the early deformation and cracking of cast-in-place concrete structures, a rigid frame end restraint shrinkage test device suitable for axial reinforcement specimens was designed and tested under different reinforcement ratios and different reinforcement arrangement methods. As a comparison, the free-end shrinkage test of concrete specimens and reinforcement specimens was carried out. Test reinforcement specimens and concrete specimens shrinkage deformation, restraint load, internal relative humidity with age development and change. The results show that under the condition of free ends, the shrinkage and drying shrinkage of the test specimens is smaller than that of the plain concrete specimens, and the restraint rate increases with the increase of the reinforcement ratio. The restrained load of the test specimens is smaller than that of the plain concrete specimens , Only 1/8 ~ 1/17 for the plain concrete specimens; the relative internal humidity of the concrete during the drying shrinkage showed a “3-stage” rule. The results provide a reference for the study of early deformation and cracking and cracking prevention measures of concrete.