基于再生粗骨料预处理的再生混凝土徐变性能试验研究

发布时间：2018-01-15 15:30

本文关键词：基于再生粗骨料预处理的再生混凝土徐变性能试验研究　出处：《福州大学》2013年硕士论文　论文类型：学位论文

【摘要】：面对砂石等资源日益匮乏,建筑废弃物日渐增加的严峻形势,促进旧混凝土的再次利用将成为解决废弃混凝土出路问题的重要途径,有明显的环境、经济与社会效益。目前国内对再生混凝土的研究主要集中在再生混凝土的基本力学性能方面,对再生混凝土徐变特性的研究还少见报道,由于再生骨料的特性与天然骨料有所不同,使再生混凝土的徐变性能与普通混凝土有较大差异。因此本文主要针对再生混凝土的徐变特征进行研究,旨在改善再生混凝土的徐变特性。主要工作和结论如下：1、通过再生混凝土基本力学性能试验,分析不同再生粗骨料取代率和不同的再生粗骨料预处理工艺(预湿法、净浆裹石工艺、掺硅灰的净浆裹石工艺)对再生混凝土基本力学性能的影响。试验表明,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；试验所用各再生粗骨料预处理工艺对再生混凝土的基本力学性能具有明显的改善作用,其中以掺硅灰的净浆裹石工艺效果最好,预湿法效果次之,最后为净浆裹石工艺。2、通过混凝土单轴受压试验,采用开放与密封处理混凝土试件的方法,研究再生粗骨料取代率的变化对再生混凝土总徐变与基本徐变特性的影响,并分析其与普通混凝土单轴受压徐变的区别。试验结果表明,随再生粗骨料取代率的增加,再生混凝土的总徐变与基本徐变显著增大。3、在不同再生粗骨料取代率的基础上,研究不同再生粗骨料预处理工艺(预湿法、净浆裹石工艺、掺硅灰的净浆裹石工艺)对再生混凝土单轴受压徐变性能的影响。试验表明,与未经骨料预处理的的再生混凝土相比,试验所采用的骨料预处理工艺对减小再生混凝土的徐变有明显效果,其中掺硅灰的净浆裹石工艺效果最好,净浆裹石工艺次之。4、对比分析试验所测再生混凝土徐变值与国内外几个广泛应用的混凝土徐变模型值的区别,选出较为合适的ACI209模型作为参考,根据再生混凝土徐变试验结果,并在ACI模型的基础上引入适当参数,建立适用于再生混凝土的徐变预测模型。
[Abstract]:Faced with the increasingly scarce resources such as sand and stone and the increasing of construction waste the promotion of the reuse of old concrete will become an important way to solve the problem of waste concrete outlet with obvious environment. Economic and social benefits. At present, the domestic research on recycled concrete mainly focuses on the basic mechanical properties of recycled concrete, and the research on creep characteristics of recycled concrete is rarely reported. Because the characteristics of recycled aggregate are different from that of natural aggregate, the creep behavior of recycled concrete is different from that of ordinary concrete, so this paper mainly focuses on the creep characteristics of recycled concrete. In order to improve the creep behavior of recycled concrete, the main work and conclusions are as follows: 1. The basic mechanical properties of recycled concrete are tested. The effects of different regenerated coarse aggregate substitution rate and different pretreatment process of recycled coarse aggregate on the basic mechanical properties of recycled concrete were analyzed. With the increase of the replacement ratio of recycled coarse aggregate, the compressive strength and elastic modulus of recycled concrete decrease in varying degrees. The pretreatment process of recycled coarse aggregate has obvious improvement on the basic mechanical properties of recycled concrete, in which silica fume is the best process, and pre-wet method is the second. Finally, through uniaxial compression test of concrete, the method of open and sealed treatment of concrete specimen is adopted. The influence of the replacement ratio of recycled coarse aggregate on the total creep and basic creep characteristics of recycled concrete is studied, and the difference between it and ordinary concrete under uniaxial compression is analyzed. The experimental results show that the creep behavior of recycled concrete is different from that of ordinary concrete under uniaxial compression. With the increase of recycled coarse aggregate replacement rate, the total creep and basic creep of recycled concrete increased significantly. On the basis of different recycled coarse aggregate replacement rate, the pretreatment process of different recycled coarse aggregate (prewet method) was studied. The effect of the technology of clean paste and stone wrapped with silica fume on the creep behavior of recycled concrete under uniaxial compression is studied. The test results show that it is compared with recycled concrete without aggregate pretreatment. The pretreatment process of aggregate used in the experiment has obvious effect on reducing creep of recycled concrete, among which silica fume has the best effect of clean paste and stone wrapping, followed by clean paste and stone wrapping technology. By comparing the creep values of recycled concrete measured by experiments with those of several widely used concrete creep models at home and abroad, a more suitable ACI209 model is selected as a reference. Based on the test results of recycled concrete creep and the introduction of appropriate parameters on the basis of ACI model, a creep prediction model suitable for recycled concrete is established.
【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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