论文中文题名: | 高品质再生混凝土骨料剔选技术的研究 |
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学号: | 201409443 |
学科代码: | 081406 |
学科名称: | 桥梁与隧道工程 |
学生类型: | 硕士 |
学位年度: | 2017 |
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专业: | |
第一导师姓名: | |
论文外文题名: | Research on Beneficiation Technique of High Quality Recycled Concrete Aggregate |
论文中文关键词: | |
论文外文关键词: | Microwave ; Recycled coarse aggregate ; Recycled concrete ; Mechanical properties ; Failure modes |
论文中文摘要: |
随着土木工程领域快速发展,大量建筑垃圾应运而生,对环境和生活造成了严重的影响,为解决这些建筑垃圾资源化再利用问题,提出一些变废为宝理念,但现有技术不够完善,存在剔选出的骨料品质比较差,二次改性成本高等缺点,使得再生混凝土不能广泛运用,现急需提出一种高品质再生混凝土骨料剔选技术,以推动再生混凝土在实际工程中的应用。
本文主要采用试验研究方法,利用微波辅助机械剔选技术对废弃混凝土块进行处理,得到高品质再生粗骨料,分别从宏观和细观两方面对其力学性能进行研究,然后配制成再生混凝土,研究其抗压性能和破坏形态。主要内容和结论如下:
(1)从粗骨料和砂浆体介电常数不同和粗骨料与砂浆体之间界面弱化原理这两方面
进行研究微波辅助机械剔选废弃混凝土块原理,最终得出本试验粗骨料和砂浆体两种材料之间粘结假说属于水泥浆体收缩假说。
(2)以900W功率的微波照射不同来源废弃混凝土块,得出最佳照射参数取值范围;通过热成像试验研究,分析废弃混凝土块表面和内部温度分布规律,探讨温度对粗骨料损伤程度;将剔选出的高品质再生粗骨料与天然粗骨料和其它剔选工艺得到的再生粗骨料的力学性能进行对比,说明微波辅助机械剔选工艺的优越性;通过电镜扫描试验,从细观角度分析再生粗骨料的损伤程度,说明微波辅助机械工艺剔选废弃混凝土块得到的的粗骨料具有高品质特性。
(3)对普通混凝土和再生混凝土抗压强度和破坏形态进行研究,从试验结果、损伤力学和断裂力学三个角度进行分析,得出再生混凝土和普通混凝土具有类似抗压强度和破坏形式,先后经历弹性阶段、微裂纹产生阶段、微裂纹发展阶段和破坏阶段,二者主要破坏形式都是砂浆体破坏,伴随着粗骨料和砂浆体界面少量破坏和表层混凝土剥落。
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论文外文摘要: |
With the rapid development of civil engineering, a large number of construction waste generates serious impact on the environment and human life. In order to solve the problem of these construction waste, some ideas recycling waste were put forward. However, the existing technology was imperfect, and the quality of aggregate was poor and the cost of secondary modification was high, which caused the recycled concrete cannot be widely applied. It was urgent to propose a high quality recycled aggregate beneficiation to promote the application of recycled concrete in practical engineering.
In this paper, the test study method was used to treat the waste concrete blocks by microwave-assisted mechanical beneficiation. The high quality recycled coarse aggregates were obtained, and their mechanical properties were studied from the macro and micro aspect respectively. Then, the recycled coarse aggregate were used to make recycled concrete, and the compressive properties and failure modes were studied. The main contents and conclusions were shown as follows:
(1)From the perspectives of different dielectric constants between coarse aggregate and mortar and the weakening principle of the interface between coarse aggregate and mortar, the principle of microwave-assisted mechanical beneficiation of waste concrete blocks was studied, and finally it was concluded that between the coarse aggregate and mortar was a hypothesis that the cement slurry shrinkage.
(2)The best range of irradiation parameters could be obtained by irradiating concrete blocks with different sources of 900W power. Through the thermal imaging tests, the surface and internal temperature distribution of waste concrete blocks were analyzed to explore the influence of temperature on the damage degree of coarse aggregate. The mechanical properties of the regenerated coarse aggregate were compared with that of the natural coarse aggregate and other high-quality recycled coarse aggregate, and the superiority of the microwave-assisted mechanical beneficiation process was illustrated. Through the scanning electron microscope tests, the damage degree of coarse aggregate was studied from the perspective of micro, indicating that the coarse aggregate selected from discarded concrete lumps by microwave-assisted mechanical process was of high quality.
(3)The compressive strength and failure mode of ordinary concrete and recycled concrete were studied. From three aspects of test results, damage mechanics and fracture mechanics, it was analyzed and concluded that recycled concrete and ordinary concrete have similar compressive strength and failure modes, which mainly experienced the elastic stage, the micro crack generation stage, the micro crack development stage and the failure stage. The main failure modes were the destruction of the mortar body, accompanying with the destruction of the interface between coarse aggregate and mortar, and the peeling of the surface concrete.
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中图分类号: | TU528 |
开放日期: | 2017-06-13 |