考虑尺寸效应的再生混凝土高温性能研究

发布时间：2018-04-17 00:09

  本文选题：再生粗骨料取代率 + 高温　； 参考：《湘潭大学》2017年硕士论文

【摘要】：自然资源的维护与合理使用一直是人类发展的一个重要方向,联合国在20世纪80年代提出了可持续发展战略。再生混凝土技术符合建筑资源可持续发展战略,已被国际认可为是一种发展绿色生态混凝土的主要措施。越来越多的学者致力于研究再生混凝土的性能和应用,但是在综合考虑再生混凝土力学性能的尺寸效应和再生混凝土高温性能方面的研究还有待进一步加强。研究高温后再生混凝土的力学性能,能有效的提高再生混凝土的应用。对高温后再生混凝土的抗压强度和再生混凝土受压性能的尺寸效应方面进行了较系统的研究。研究的主要内容有:首先对再生粗骨料进行加工处理,经过机械及人工加工处理后得到试验所需要的再生粗骨料,测试了再生粗骨料的基本性能。与天然骨料的研究对比发现,再生粗骨料较天然骨料表观密度提高了1.39%,堆积密度降低了11.4%,吸水率提高了4.07%,压碎指标值提高了6.18%。其次,对高温后再生混凝土的抗压性能进行了系统的试验研究。由试验过程和结果分析发现,再生混凝土试块随着温度的不断升高,试块表观变化经历了从青灰色—浅灰色—灰褐色—熏黑的过程,再生混凝土与普通混凝土的表观颜色变化过程区别不大。随着温度的不断升高,再生混凝土试块的质量逐渐减少,从20℃到400℃的质量损失大于400℃到600℃。随着温度的逐渐升高,再生混凝土的抗压强度逐渐降低,这一点和普通混凝土相似。以再生粗骨料取代率为100%的再生混凝土(RC100)为例,从20℃到200℃时,残余抗压强度下降了4.58%,从200℃到400℃残余抗压强度下降了3.93%,400℃到600℃的残余抗压强度下降了9.06%。可以看出随着温度的升高,再生混凝土的残余抗压强度下降值有所不同,其中400℃到600℃再生混凝土的残余抗压强度下降值最大。再次,研究了再生粗骨料取代率对高温后再生混凝土抗压强度的影响以及再生粗骨料取代率对再生混凝土抗压强度尺寸效应的影响。试验结果表明:再生粗骨料取代率的增加对再生混凝土的受压性能尺寸效应影响不大,而随着再生粗骨料取代率的增加高温后再生混凝土的残余抗压强度呈现出不断降低的趋势。最后,研究了再生混凝土抗压强度的尺寸效应,对试验结果分析后可以得到:再生混凝土抗压强度的尺寸效应较为明显,边长为100mm的立方体试件的抗压强度值和边长为200mm的立方体试件的抗压强度值相对于边长为150mm的立方体标准试件的抗压强度值,其尺寸效应系数分别在(0.98~0.94)和(1.13~1.03),取平均值为0.96和1.08。建立了不同截面尺寸之间再生混凝土立方体抗压强度的相关关系。
[Abstract]:The maintenance and rational use of natural resources has always been an important direction of human development. The United Nations put forward the strategy of sustainable development in the 1980s.The recycled concrete technology is in line with the sustainable development strategy of building resources and has been recognized as a major measure for the development of green ecological concrete.More and more scholars devote themselves to study the properties and applications of recycled concrete, but the research on the dimension effect and high temperature performance of recycled concrete still needs to be further strengthened.Studying the mechanical properties of recycled concrete after high temperature can effectively improve the application of recycled concrete.The compressive strength of recycled concrete after high temperature and the size effect of compressive performance of recycled concrete are studied systematically.The main contents of the research are as follows: firstly, the recycled coarse aggregate is processed, and the recycled coarse aggregate is obtained after mechanical and manual processing, and the basic properties of the recycled coarse aggregate are tested.Compared with the natural aggregate, the apparent density of regenerated coarse aggregate increased by 1.39, the accumulation density decreased by 11.4 percent, the water absorption rate increased by 4.07, and the crushing index value increased by 6.18.Secondly, the compressive performance of recycled concrete after high temperature is studied systematically.According to the experimental process and the analysis of the results, it is found that the apparent change of the recycled concrete specimen goes through the process of green gray, light gray, grayish brown and black with the increasing of temperature.The process of apparent color change of recycled concrete and ordinary concrete is not different.With the increasing of temperature, the mass of recycled concrete samples decreases gradually, and the mass loss from 20 鈩，

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