再生混凝土抗氯离子渗透性试验研究
发布时间：2019-04-26 07:03
【摘要】：近年来,城市建筑垃圾再利用受到广泛的重视,许多国家将破碎后的混凝土废弃物作为骨料重新利用,不仅能有效地节约天然的优质骨料,而且对合理利用自然资源和保护生态环境具有重要现实意义。再生混凝土由于再生骨料孔隙,界面,吸水性等缺陷,导致耐久性问题成为阻碍再生混凝土应用于工程结构的主要影响因素。为了推广再生混凝土在实际工程结构中的应用,其抗氯离子渗透性能成为亟待研究和解决的问题。本文针对再生混凝土的自身的特点,进行了以下方面的研究：1.采用ASTM1202方法进行再生混凝土电通量试验,研究再生粗骨料取代率、矿物掺合料种类、不同的拌制方法和养护龄期对再生混凝土抗氯离子渗透性能的影响,同时分析以上因素对再生混凝土宏观力学性能的影响。试验的结果表明：随着再生粗骨料取代率的增加,再生混凝土的抗压强度和抗氯离子渗透性呈下降趋势。延长养护龄期有助于抗压强度的和抗氯离子渗透性的提高,其提高幅度与拌制方法及再生粗骨料取代率有关。2.研究再生混凝土抗压强度与抗氯离子渗透性的关系,结果表明：养护龄期为28d与60d的再生混凝土与电通量值之间的线性相关性较差。但龄期为28d的再生混凝土的抗压强度与电通量呈二次多项式关系。3.通过课题组设计的应力加载装置研究再生粗骨料取代率、弯曲应力水平、矿物掺合料种类、加载龄期对再生混凝土抗氯离子渗透性能的影响。试验结果表明：随着再生粗骨料取代率的增加,再生混凝土的扩散系数也随之增大。随着弯曲应力水平的提高,矿物掺合料种类对氯离子扩散系数的影响变小。当加载应力为0.5Pu时,弯曲荷载对取代率为100%的再生混凝土的渗透性影响显著大于50%取代率。因此荷载应力成为影响再生混凝土渗透的主要因素。氯离子渗透深度与加载浸泡龄期的平方根具有较好的线性关系。4.依据现有普通混凝土的氯离子扩散模型和本文试验结果初步拟合考虑再生粗骨料取代率、加载应力水平的再生混凝土氯离子扩散模型,采用经验公式初步估算再生混凝土在氯盐环境下的使用寿命。结果表明：改进拌制方法,添加矿物掺合料均能不同程度的提高再生混凝土的耐久性。
[Abstract]:In recent years, the reuse of urban construction waste has received extensive attention. In many countries, broken concrete waste can be reused as aggregate, which can not only save natural high-quality aggregate effectively. Moreover, it is of great practical significance for the rational utilization of natural resources and the protection of ecological environment. The durability of recycled concrete has become the main factor which hinders the application of recycled concrete in engineering structure due to the defects such as pore interface and water absorption of recycled aggregate. In order to popularize the application of recycled concrete in practical engineering structures, the chloride penetration resistance of recycled concrete has become an urgent problem to be studied and solved. In this paper, according to the characteristics of recycled concrete, the following aspects of research have been carried out: 1. The electric flux test of recycled concrete was carried out by using ASTM1202 method. The influence of the substitution rate of recycled coarse aggregate, the type of mineral admixture, different mixing methods and curing age on the resistance to chloride ion penetration of recycled concrete was studied. At the same time, the influence of the above factors on the macro-mechanical properties of recycled concrete is analyzed. The experimental results show that the compressive strength and chloride ion permeability of recycled concrete decrease with the increase of the substitution rate of recycled coarse aggregate. Prolongation of curing age contributes to the improvement of compressive strength and resistance to chloride ion permeability, which is related to the mixing method and the replacement rate of recycled coarse aggregate. 2. The relationship between compressive strength and chloride ion permeability of recycled concrete is studied. The results show that the linear correlation between reclaimed concrete with age of 28 days and 60 days is poor. But the relationship between compressive strength and electric flux of recycled concrete aged 28 days is quadratic polynomial. 3. The influence of substitution rate of recycled coarse aggregate, bending stress level, type of mineral admixture and loading age on chloride ion penetration resistance of recycled concrete was studied by stress loading device designed by our research group. The experimental results show that the diffusion coefficient of recycled concrete increases with the increase of the substitution rate of recycled coarse aggregate. With the increase of bending stress, the effect of mineral admixtures on chloride diffusion coefficient becomes smaller. When the loading stress is 0.5Pu, the influence of bending load on the permeability of recycled concrete with 100% replacement rate is significantly greater than that of 50% replacement rate. Therefore, the load stress has become the main factor affecting the permeability of recycled concrete. There is a good linear relationship between chloride penetration depth and square root of immersion age. 4. According to the existing chloride ion diffusion model of ordinary concrete and the experimental results of this paper, the chloride ion diffusion model of recycled concrete considering the substitution rate of recycled coarse aggregate and loading stress level is preliminarily fitted. An empirical formula is used to estimate the service life of recycled concrete in chloride environment. The results show that the durability of recycled concrete can be improved by improving mixing method and adding mineral admixture.
【学位授予单位】：福州大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU528
[Abstract]:In recent years, the reuse of urban construction waste has received extensive attention. In many countries, broken concrete waste can be reused as aggregate, which can not only save natural high-quality aggregate effectively. Moreover, it is of great practical significance for the rational utilization of natural resources and the protection of ecological environment. The durability of recycled concrete has become the main factor which hinders the application of recycled concrete in engineering structure due to the defects such as pore interface and water absorption of recycled aggregate. In order to popularize the application of recycled concrete in practical engineering structures, the chloride penetration resistance of recycled concrete has become an urgent problem to be studied and solved. In this paper, according to the characteristics of recycled concrete, the following aspects of research have been carried out: 1. The electric flux test of recycled concrete was carried out by using ASTM1202 method. The influence of the substitution rate of recycled coarse aggregate, the type of mineral admixture, different mixing methods and curing age on the resistance to chloride ion penetration of recycled concrete was studied. At the same time, the influence of the above factors on the macro-mechanical properties of recycled concrete is analyzed. The experimental results show that the compressive strength and chloride ion permeability of recycled concrete decrease with the increase of the substitution rate of recycled coarse aggregate. Prolongation of curing age contributes to the improvement of compressive strength and resistance to chloride ion permeability, which is related to the mixing method and the replacement rate of recycled coarse aggregate. 2. The relationship between compressive strength and chloride ion permeability of recycled concrete is studied. The results show that the linear correlation between reclaimed concrete with age of 28 days and 60 days is poor. But the relationship between compressive strength and electric flux of recycled concrete aged 28 days is quadratic polynomial. 3. The influence of substitution rate of recycled coarse aggregate, bending stress level, type of mineral admixture and loading age on chloride ion penetration resistance of recycled concrete was studied by stress loading device designed by our research group. The experimental results show that the diffusion coefficient of recycled concrete increases with the increase of the substitution rate of recycled coarse aggregate. With the increase of bending stress, the effect of mineral admixtures on chloride diffusion coefficient becomes smaller. When the loading stress is 0.5Pu, the influence of bending load on the permeability of recycled concrete with 100% replacement rate is significantly greater than that of 50% replacement rate. Therefore, the load stress has become the main factor affecting the permeability of recycled concrete. There is a good linear relationship between chloride penetration depth and square root of immersion age. 4. According to the existing chloride ion diffusion model of ordinary concrete and the experimental results of this paper, the chloride ion diffusion model of recycled concrete considering the substitution rate of recycled coarse aggregate and loading stress level is preliminarily fitted. An empirical formula is used to estimate the service life of recycled concrete in chloride environment. The results show that the durability of recycled concrete can be improved by improving mixing method and adding mineral admixture.
【学位授予单位】：福州大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU528
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