干湿循环作用下氯离子在聚丙烯纤维混凝土中传输性能研究

Chloride Ion Transport in Polypropylene Fiber Concrete under Dry-Wet Cycle

为探究干湿循环作用下聚丙烯纤维混凝土中氯离子的传输规律,设计了四种掺量的聚丙烯纤维混凝土,对其在不同干湿循环周期下的自由氯离子含量和总氯离子含量进行测量,分析聚丙烯纤维掺入对混凝土氯离子结合性能及氯离子扩散系数的影响。结果表明:0.15%(体积分数,下同)聚丙烯纤维的掺入可以增加混凝土密实度,降低自由氯离子含量;而大量纤维的掺入(<0.45%)导致混凝土内部自由氯离子含量增加,增大了混凝土的氯离子结合能力。聚丙烯纤维掺量0%~0.45%范围内,氯离子结合能力与纤维掺量存在二次函数关系。聚丙烯纤维的掺入降低了干湿循环后期氯离子扩散系数,增大了时间依赖系数m,有利于提高混凝土抗氯离子侵蚀能力。

In order to explore the transmission law of chloride ions in polypropylene fiber concrete under the action of dry-wet cycles,four types of polypropylene fiber concrete were designed for experiments,and the free chloride ion content and total chloride ion content were measured under different dry-wet cycles.Measure and analyze the influence of polypropylene fiber incorporation on the chloride ion binding performance and chloride ion diffusion coefficient of concrete.The results show that the incorporation of 0.15%(volume fraction,same below)polypropylene fiber increases the compactness of concrete and reduces the content of free chloride ion.While the incorporation of a large number of fibers(<0.45%)leads to an increase in the content of free chloride ion in the concrete and increases the chloride ion content of the concrete.Ion binding capacity.In the range of 0%to 0.45%of polypropylene fiber content,the chloride ion binding capacity has a quadratic function relationship with the fiber content.The incorporation of polypropylene fiber reduces the chloride ion diffusion coefficient in the later stage of the dry-wet cycle and increases the time-dependent coefficient m,which is beneficial to improve the resistance of concrete to chloride ion erosion.