荷载损伤后纤维轻骨料混凝土氯离子侵蚀研究

为研究荷载损伤对纤维轻骨料混凝土抵抗氯离子侵蚀性能的影响，设计了掺加聚丙烯纤维、钢 聚丙烯纤维、钢纤维3种轻骨料混凝土，开展了抗拉和抗压试验。分别在40%，60%，80%极限荷载3种拉、压应力水平下持续加载60 s，并测量加载后的残余应变。卸载后将试件切割成直径100 mm、厚50 mm的圆柱体，通过NEL法测定氯离子扩散系数。研究结果表明:混凝土残余应变随着拉、压荷载等级的增大而增大，纤维对轻骨料混凝土极限强度和变形能力提高显著；未施加荷载时，随着纤维的增加，单掺聚丙烯纤维组氯离子扩散系数变小，混掺纤维组基本保持不变，钢纤维组显著增加；施加荷载后，纤维的增加没有显著改善轻骨料混凝土抗氯离子侵蚀能力；残余应变与氯离子扩散系数间存在正相关特性，残余应变越大，氯离子扩散系数越大。

Study on Chloride Ion Penetration in Fiber Reinforced Lightweight Aggregate Concrete with Load Damages

In order to study the influence of load damages on the chloride ion resistance of fiber reinforced lightweight aggregate concrete, three types of lightweight aggregate concrete mixed with polypropylene fiber, steel and polypropylene fiber, steel fiber were designed, respectively. And then tensile test and compression test of the three types of concrete were carried out. Stress levels of 40%, 60% and 80% of limit load were applied on the specimens for 60 s and the residual strain was measured subsequently. After loading, the specimens were cut into cylinders with the diameter of 100 mm and the height of 50 mm, and the chloride ion diffusion coefficients of the specimen were measured based on the NEL method. The research results show that the residual strain of concrete increases with the increasing of tensile and compressive load levels and the fibers can improve the ultimate strength and deformation ability of lightweight aggregate concrete significantly. For the condition without load, chloride ion diffusion coefficient only for the group with polypropylene fiber added decreases with the increasing of fiber volume fraction, that of the steel and polypropylene hybrid fiber reinforced group keeps mostly unchangeable and the steel fiber reinforced group increases significantly. After loading, there is no substantial improvement on concrete chloride ion penetration resistance with the increasing of the volume fraction of fibers. The positive correlation exists between residual strain and diffusion coefficients of chloride ion for fiber reinforced lightweight concrete. The greater residual strain is, the greater diffusion coefficient of chloride ion is.