C50桥用自密实混凝土制备研究

发布时间：2018-03-25 07:54

本文选题：自密实混凝土　切入点：桥梁　出处：《燕山大学》2014年硕士论文

【摘要】：随着国民经济的飞速发展，作为枢纽工程，桥梁建设也因此迎来了一个高峰期。混凝土是桥梁建设中最主要的材料，如何保证桥梁混凝土质量成为人们关注的焦点。本文根据秦皇岛地区混凝土桥梁质量的调查分析，提出采用自密实混凝土方法来解决桥梁混凝土出现的表观质量问题。自密实混凝土由于浆集比大，，胶凝材料用量多，弹性模量相对较低，成为应用于桥梁的劣势。针对桥梁混凝土对早期强度和弹性模量的特殊要求，以及秦皇岛地区缺乏优质矿物掺合料的现状，采用理论分析和实验研究相结合的方式，通过降低水胶比、优化粉煤灰掺量和砂率等主要参数，制备出了7d抗压强度为46.1MPa、28d抗压强度为61.4MPa和弹性模量为36.6GPa的桥用自密实混凝土。研究结果表明：现有自密实混凝土配合比计算方法均没有考虑桥用混凝土对早期强度和弹性模量的特殊要求，以及缺乏优质矿物掺合料的现状，因此需要对计算出的自密实混凝土配合比参数进行调整；二级粉煤灰的细度不够，其对胶凝材料净浆流动度改善作用不明显，起不到微集料填充作用，不能通过置换出浆体中的填充水来提高流动性；采用本文选用的材料，在胶凝材料总量为530kg/m3时，自密实混凝土的强度值最高，当胶凝材料总量增大到570kg/m3时强度反而降低；砂率对自密实混凝土工作性能有很大影响，随着砂率的增大，自密实混凝土的流动性先增大再减小，最佳砂率为45%；制备出的自密实混凝土比秦皇岛地区使用的同强度等级的混凝土每立方米节省成本16.78元，技术经济效果明显，具有广阔的推广前景。
[Abstract]:With the rapid development of the national economy, as a hub project, bridge construction also ushered in a peak period. Concrete is the most important material in bridge construction, how to ensure the quality of bridge concrete has become the focus of attention. Based on the investigation and analysis of the quality of concrete bridges in Qinhuangdao area, a self-compacting concrete method is proposed to solve the apparent quality problems of bridge concrete. The elastic modulus is relatively low, which becomes the disadvantage of bridge application. In view of the special requirement of early strength and elastic modulus of bridge concrete, and the lack of high quality mineral admixture in Qinhuangdao area, By means of theoretical analysis and experimental study, by reducing the ratio of water to binder and optimizing the content of fly ash and sand ratio, the self-compacting concrete for bridges with 7d compressive strength of 46.1 MPA / 28d and elastic modulus of 36.6GPa was prepared. The results show that the present calculation methods of self-compacting concrete mixture ratio do not take into account the special requirements of bridge concrete for early strength and elastic modulus, as well as the present situation of lack of high quality mineral admixture. Therefore, it is necessary to adjust the parameters of the calculated self-compacting concrete mixture ratio. The fineness of the secondary fly ash is not enough, and the effect of the secondary fly ash on the flow of cement paste is not obvious, which can not play the role of micro-aggregate filling. The strength of self-compacting concrete is the highest when the total amount of cementing material is 530kg/m3, but the strength of self-compacting concrete decreases when the total amount of cementing material increases to 570kg/m3. Sand ratio has a great influence on the working performance of self-compacting concrete. With the increase of sand ratio, the fluidity of self-compacting concrete increases first and then decreases. The best sand rate is 450.The prepared self-compacting concrete saves 16.78 yuan per cubic meter compared with the same strength concrete used in Qinhuangdao area.
【学位授予单位】：燕山大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U444

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