改性聚酯纤维在混凝土中的分散性及对耐久性的影响

制备了不同纤维掺量的改性聚酯纤维混凝土，通过纤维分散的图像处理方法研究五种不同搅拌方式对改性聚酯纤维在混凝土中分散性能的影响，并通过耐久性试验研究改性聚酯纤维混凝土的抗碳化、抗氯盐侵蚀和抗冻性能.结果表明，图像处理方法能够较好地评价改性聚酯纤维混凝土中的纤维分散性，认为“砂石胶材60 s+水60 s+纤维60 s”的搅拌方式得到的纤维分散性最好，与肉眼观察的效果一致.掺加改性聚酯纤维能够提高混凝土的抗压强度，掺量为1.1 kg·m-3时提高强度14%左右，继续增大纤维掺量不能持续提升强度.改性聚酯纤维在混凝土中的密集分布能够削弱CO2的扩散，降低混凝土的碳化速率12.6%~18.9%，纤维掺量越多，抗碳化能力越好.掺加改性聚酯纤维能够降低混凝土的氯离子扩散系数，提高其抗氯离子侵蚀能力.改性聚酯纤维还能有效减少冻融循环过程中表层材料的剥落，大大改善混凝土的抗冻性.

Dispersivity of modified polyester fibers in concrete and its influence on the durability of concrete

Modified polyester fiber reinforced concrete with different additions was prepared. The dispersivity of modified polyes-ter fibers in concrete by five different mixing methods was studied by an image processing method. With a series of durability tests, the carbonation resistance, chloride penetration resistance and frost resistance of the fiber reinforced concrete were also investigated. The results indicate that the image processing method can evaluate the dispersivity of the fiber reinforced concrete well. The mixing method of “aggregate and binding materials for 60 s+water for 60 s+fiber for 60 s” makes the best dispersivity of modified polyester fibers. It is in accord with direct observations by naked eyes. The compressive strength is increased by the addition of modified polyester fibers. After adding 1. 1 kg·m-3 modified polyester fibers, the compressive strength of concrete increases by 14%; but with more modified polyester fibers, the compressive strength no longer increases. The existence of modified polyester fibers in concrete can slow down the diffusion of CO2 , the carbonation rate of concrete decreases by 12. 6% to 18. 9%, and with more modified polyester fibers, the carbonation resistance became better. After the addition of modified polyester fibers, the chloride diffusion coefficient of concrete also decreases. The modified polyester fibers can reduce the surface spalling of concrete during freeze-thaw cycles, which improves the frost resistance of concrete significantly.