自密实碱激发混凝土抗氯离子侵蚀性能研究

Research on the Resistance of Self-compacting Alkali-Activated Concrete to Chloride Ion Erosion

摘要:

为探究自密实混凝土的绿色低碳化方案,采用干湿循环加速试验法,开展了自密实碱激发混凝土与自密实水泥混凝土的抗氯离子侵蚀性能对比研究,对混凝土的游离氯离子含量、氯离子总含量、氯离子结合能力以及表观氯离子扩散系数等指标进行分析。结果表明,当氯离子侵蚀龄期与深度一定时,自密实水泥混凝土的游离氯离子和总氯离子含量最大,自密实碱激发混凝土次之,2%纳米SiO₂改性自密实碱激发混凝土最小;与自密实水泥混凝土相比,自密实碱激发混凝土的氯离子结合能力提高了29.90%,表观氯离子扩散系数更低,抗氯离子侵蚀能力更强;掺入纳米SiO₂虽降低了自密实碱激发混凝土结合氯离子的能力,但同时也降低了表观氯离子扩散系数。

Abstract:

To explore a green and low-carbon scheme for self-compacting concrete, a comparative study on the chloride ion erosion resistance of self-compacting alkali-activated concrete and self-compacting cement concrete was conducted using the dry-wet cycle accelerated test method. The free chloride ion content, total chloride ion content, chloride ion binding capacity, and apparent chloride diffusion coefficient of concrete were analyzed. The results indicate that when the chloride ion erosion duration and depth are constant, the free chloride ion and total chloride ion contents are the highest in self-compacting cement concrete, followed by self-compacting alkali-activated concrete, and the lowest in self-compacting alkali-activated concrete modified with 2% nano-SiO₂. The chloride ion binding capacity of self-compacting alkali-activated concrete is 29.90% higher than that of self-compacting cement concrete, and its apparent chloride diffusion coefficient is lower, demonstrating superior resistance to chloride ion erosion. Although the incorporation of nano-SiO₂ reduces the chloride ion binding capacity of self-compacting alkali-activated concrete, it also contributes to a decrease in the apparent chloride diffusion coefficient.