索塔锚固区用HPFRC的塑性收缩与干燥收缩

钢锚箱锚固区部位所处环境复杂，为确保其耐久性，制备了专用高性能纤维混凝土（HPFRC）.模拟干热环境，对优选出的泵送性能优异的高性能混凝土（HPC）和高性能纤维混凝土（HPFRC）进行了塑性收缩试验；研究了纤维掺量和种类对塑性收缩和干燥收缩性能的影响，并对其机理进行了探讨。研究表明：随着纤维掺量的增加，塑性收缩的开裂总面积下降，混凝土的抗裂等级提高；当钢纤维的体积掺量超过0．8％，高性能铜纤维混凝土自由干燥66d的收缩值同高性能混凝土相比下降了50％；纤维体积率为0．1％的聚丙烯纤维与体积率为0．6t％的钢纤维混杂后，对抑制塑性收缩和干燥收缩效果显著？

Study on Plastic Shrinkage and Drying Shrinkage of HPFRC in Anchorage Zone Between Steel Anchorage Box and Cable in Bridge Tower

Concerning the complexity of durability of concrete in anchorage zone between Steel anchorage box and cable in bridge tower,special high performance fiber reinforced concrete(HPFRC) was introduced in the tower construction.In the paper,the effect of hot weather conditions on plastic shrinkage cracking of high performance concrete(HPC) and HPFRC were investigated by the method of artificial imitation in the lab.The effect of content and types of fibers on plastic shrinkage cracking and drying shrinkage of HPFRC was also studied.In the end,influence mechanisms were explained.The experimental results showed that with the increase of content of fiber used in HPC,the total areas of plastic cracking decreased and the concrete anti-cracking grade improved.For HPC in which volume fraction of steel fibers was over 0.8%,the unrestrained drying shrinkage could be diminished by about 50%.The test results also showed that when 0.10% volume fraction of polypropylene fibers together with 0.6% steel fibers(by volume) were added into HPC,plastic shrinkage cracking and unrestrained drying shrinkage diminished obviously at early age.