基于再生粗骨料预处理的高性能再生混凝土自生收缩性能试验研究

发布时间：2018-06-25 06:33

本文选题：再生混凝土 + 高性能　；参考：《福州大学》2013年硕士论文

【摘要】：随着建筑业的发展,再生混凝土的研究与应用已经成为土木工程中一个重要的发展方向。目前,国内对于再生混凝土已经有了较深入的研究,但对高性能再生混凝土的研究较少,特别是对高性能再生混凝土的自生收缩性能的研究还少见报道。由于再生粗骨料的特性,再生混凝土的自生收缩有别于普通混凝土。因此,本文开展了对高性能再生混凝土自生收缩性能的试验研究,旨在优化高性能再生混凝土的自生收缩性能。主要工作与结论如下：1、利用平均强度C30的废弃混凝土生产再生粗骨料,参考普通混凝土高性能化的途径,通过试验配制出C40等级的高性能再生混凝土,其坍落度在200mmm左右,满足现代商品混凝土的泵送要求。进行了高性能再生混凝土基本力学性能试验,其结果表明,随着再生粗骨料取代率的增加,再生混凝土的抗压强度、弹性模量有不同程度的降低。预湿法、净浆裹石工艺、掺加硅灰的净浆裹石工艺都不同程度提高了再生混凝土的抗压强度、弹性模量。2、采用非接触法测量高性能再生混凝土的自生收缩。其整机一体化的设置和非接触的测定方式提高了试验结果的准确性及可靠性。自生收缩试件早期出现了膨胀现象,在混凝土的膨胀达到峰值后,混凝土开始产生自生收缩变形。因此,本文选择混凝土的膨胀峰值点作为自生收缩的起点,以便更好地指导工程实践。3、通过自生收缩试验研究了不同再生粗骨料取代率、不同的再生粗骨料强化预处理方法对高性能再生混凝土自生收缩的影响。试验结果表明,随着再生粗骨料取代率的增加,再生混凝土的自生收缩也随着增大。在相同条件下,再生混凝土的自生收缩比普通混凝土更大,特别是混凝土的早期自生收缩。预湿法能够很好地改善再生混凝土的自生收缩性能,净浆裹石工艺较好地改善了其自生收缩性能,而掺加硅灰的净浆裹石工艺则增加了再生混凝土的自生收缩。4、分析比较了各普通高性能混凝土的自生收缩预测模型的优缺点及与本文试验结果的差异。选取欧洲规范BS EN模型为参考,通过参数修正提出适用于高性能再生混凝土自生收缩的预测模型。
[Abstract]:With the development of construction industry, the research and application of recycled concrete has become an important development direction in civil engineering. At present, there has been more in-depth research on recycled concrete in China, but there are few researches on high performance recycled concrete, especially on the in-situ shrinkage of high performance recycled concrete. Due to the characteristics of recycled coarse aggregate, the self-growth shrinkage of recycled concrete is different from that of ordinary concrete. Therefore, an experimental study on the autogenous shrinkage of high performance recycled concrete is carried out in order to optimize the autogenous shrinkage of high performance recycled concrete. The main work and conclusions are as follows: 1. The recycled coarse aggregate is produced by using the waste concrete with average strength of C30. The slump of the recycled concrete of C40 grade is about 200mmm through the experiment, referring to the way of high performance of ordinary concrete. Meet the pumping requirements of modern commercial concrete. The basic mechanical properties of high performance recycled concrete were tested. The results showed that the compressive strength and elastic modulus of recycled concrete decreased in varying degrees with the increase of the replacement ratio of recycled coarse aggregate. The compressive strength and elastic modulus of recycled concrete were improved to some extent by pre-wetting method, paste and stone wrapping process and adding silica fume. The non-contact method was used to measure the autogenous shrinkage of high performance recycled concrete. The accuracy and reliability of the test results are improved by the integrative setting of the whole machine and the non-contact measurement method. When the expansion of concrete reaches its peak value, the concrete begins to produce autogenous shrinkage deformation. Therefore, in this paper, the expansion peak point of concrete is chosen as the starting point of autogenous shrinkage, in order to guide engineering practice better. The replacement rate of different recycled coarse aggregate is studied through the test of autogenous shrinkage. The effect of different recycled coarse aggregate strengthening pretreatment methods on the autogenous shrinkage of high performance recycled concrete. The experimental results show that the autogenous shrinkage of recycled concrete increases with the increase of the replacement ratio of recycled coarse aggregate. Under the same conditions, the autogenous shrinkage of recycled concrete is greater than that of ordinary concrete, especially the early autogenous shrinkage of concrete. The prewetting method can improve the in-situ shrinkage of recycled concrete, and the self-growing shrinkage of recycled concrete can be improved by the process of clean paste and stone wrapping. On the other hand, the self-growing shrinkage of recycled concrete is increased with the addition of silica fume. The advantages and disadvantages of the prediction models of the autogenous shrinkage of ordinary high performance concrete and the difference between the experimental results and the experimental results are analyzed and compared. Based on the reference of the European Standard BS en model, a prediction model for the autogenous shrinkage of high performance recycled concrete is proposed by modifying the parameters.
【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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