【作者】 易全新；

【导师】 安明喆；

【作者基本信息】 北京交通大学 ， 结构工程， 2007， 硕士

【摘要】 本论文进行了不同胶凝材料体系混凝土的耐久性能研究,主要考察抗氯离子渗透性能以及抗硫酸盐侵蚀性能。通过ASTM C1202-97测定了不同胶凝材料体系混凝土在不同龄期的导电性能,通过对比试验结果,得出了矿物掺和料的最佳掺加比例。研究中,还运用氯离子扩散系数的预测公式,对试验中采用的各种类型的混凝土进行了抗氯离子渗透性能的评价,比较了试验结果与计算结果之间的差异。此外,研究还测定了混凝土养护至不同龄期时,分别暴露于两种不同的硫酸盐侵蚀环境——长期浸泡以及干湿循环的条件下抗压强度以及试件质量的变化,以作为混凝土抗硫酸盐侵蚀性能的评价指标。ASTM C1202-97电量测试结果表明,掺入矿物掺和料能在不损失混凝土长期强度的情况下显著提高混凝土的抗氯离子渗透性能。在本论文所采用的胶凝材料体系中,矿粉与硅粉复合所产生的效果最好。在总的水泥取代量为40%的情况下,矿粉与粉煤灰以1:1复合掺加时,效果要明显优于单掺矿粉和粉煤灰的情况。在试验过程中,初始电流与总的电通量呈线性关系,说明在一定条件下,利用初始电流来代替电通量来评价混凝土的抗氯离子渗透性能是可行的,但适用范围仍有待确定。预测氯离子扩散系数的公式能在一定程度上反映出不同胶凝材料体系的混凝土的抗氯离子渗透性能,然而该公式只考虑了矿物掺和料的掺量这一因素,忽略掉了材料本身的物理化学指标,因而不能精确定量各种胶凝材料对混凝土抗氯离子渗透性能的贡献作用。混凝土养护至不同龄期后,暴露于不同的侵蚀环境—长期浸泡和干湿循环。用干湿循环这一试验制度来评价混凝土的抗硫酸盐侵蚀性能,与长期浸泡的试验制度相比,加快了混凝土的劣化速度。矿物掺和料的使用能明显降低硫酸盐侵蚀引起的混凝土强度损失。此外,硫酸盐溶液的浓度越高,混凝土腐蚀进程加快。混凝土在遭受硫酸盐侵蚀时,强度损失比质量损失更为敏感。在本论文的试验周期内,一定试验条件下的混凝土开始出现抗压强度损失,但相应的试件质量却持续增加。混凝土暴露于硫酸盐环境的时间对试验结果也有明显的影响。达到28天龄期开始进行硫酸盐侵蚀试验的混凝土试件,其劣化程度要比达到60天龄期开始进行硫酸盐侵蚀试验的混凝土试件更为严重。这是由于混凝土随着龄期的增长,其内部结构进一步密实所引起的。因此,提高混凝土内部结构的密实度是提高混凝土抗硫酸盐侵蚀的有效途径之一。更多还原

【Abstract】 This thesis presents experimental studies on the resistance to chloride ion permeability and sulfate erosion of concretes with different binder systems. Electrical conductivity of concrete at different ages is tested by ASTMC1202-97. By comparing the experiment result, the most optimum binder system is identified. Besides, a formula predicting chloride diffusion coefficient is used to evaluate the resistance to chloride ion permeability of concrete with different binder system, and the data obtained from this calculation are taken to compare with the experiment results. The resistance of sulfate erosion of concrete is also evaluated. When cured to different ages, specimens are put into two different sulfate environments, dipped in solution of sodium sulfate or subjected to wet-dry cycle. Loss of weight and compressive strength are considered as referenced index.It can be concluded from data of electrical conductivity tested that mineral admixture can improve the resistance to chloride ion permeability of concrete obviously without loss of strength. In all binder system adopted in this paper, compound of slag and silica fume is most effective. Moreover, compound of slag and fly ash can be better than each of them mixed into concrete separately. The best ratio of slag to fly ash in this experiment is 1:1. In the process of this testing program, the final electrical quantities are linearly dependent on electrical current in initial stage, therefore, initial current can instead of electrical quantities and become referenced index to evaluate the resistance to chloride ion of concrete under some conditions, but the sphere of application is not identified.The formula can predict the resistance to chloride ion permeability of concrete approximately by calculating chloride diffusion coefficient. However, it still leaves much to be desired. To measure the effect arising from different kinds of mineral materials system accurately, not only the dosage of mineral admixtures, but the physical property parameter should be taken into consideration.When cured to different ages, specimens are put into two different sulfate environments; Subjecting to wet-dry cycle is more severe than dipping, and increasing the concentration of solution is anther effective way to accelerate the deterioration rate of concrete. As the referenced index, Loss of strength is more sensitive to sulfate更多还原