高性能混凝土的拉伸徐变特性

Study on Tensile Creep Characteristics of High Performance Concrete

掌握拉伸徐变行为是进行混凝土应力分析和开裂预测的重要前提。采用自行设计的混凝土拉伸徐变试验装置,系统研究了不同加载龄期(1、3、7d)、不同水胶比(0.29、0.33、0.37)和不同粉煤灰掺量(0%、20%、40%)下高性能混凝土的拉伸徐变特性。实验结果表明,拉伸徐变随加载龄期和水胶比的增大而显著减小。粉煤灰掺入可以明显提高混凝土抵抗徐变的能力,且随掺量的增加而增强。拉伸徐变可抵消42%~62%的自由收缩,降低混凝土早期开裂的风险。

The understanding of tensile creep behavior is extremely important in accurate stress analysis and crack prediction.A set of concrete tensile creep testing apparatus was constructed.The characteristics of tensile creep under different loading ages(1,3and 7days),different water-binder ratio(0.29,0.33and 0.37)and different fly ash proportion(0%,20%and 40%)were discussed.The results show that tensile creep of HPC decreases as the loading age and water-binder ratio increases.The creepresistance of HPC enhances with the increase of fly ash proportion.Tensile creep counteracts free shrinkage by 42%~62%, decreases the possibility of cracking of HPC at early ages.