再生混凝土基本力学性能及微观机理研究

发布时间：2018-05-16 17:13

本文选题：再生骨料混凝土 + 力学性能　；参考：《广西大学》2013年硕士论文

【摘要】：从可持续发展的角度出发,将废弃的混凝土加工成再生骨料用于再生骨料混凝土能很好的解决骨料资源和生态坏境相互协调发展的问题。由于再生骨料的来源各不相同及其自身区别于自然骨料的特有性质：高孔隙率、高吸水率、低密度、低坚固性及低耐磨性,造成了再生骨料混凝土的性能与自然骨料混凝土有很大的不同。本文从宏观角度出发,结合再生骨料混凝土界面区的微观结构及水化产物,对再生骨料混凝土性能进行了研究,主要内容如下：一、对不同再生骨料替代率的再生骨料混凝土的基本力学性能进行了测试。通过试验发现,随着再生骨料替代率的增大,再生混凝土的立方体抗压强度和棱柱体轴心抗压强度逐渐降低,当再生骨料替代率小于50%时,再生骨料对再生混凝土的正负效应达到最大。对不同再生骨料替代率下再生混凝土进行了弹性模量测试,发现随着再生骨料替代率的增大,混凝土弹性模量总体上呈现下降的趋势。二、对再生骨料界面区进行了显微硬度、扫描电镜及X衍射测试。结果发现在新旧水泥石界面区及新水泥石与自然骨料界面区存在一层“膜”,并且新旧水泥石界面区的这层“膜”厚度大约为20-40μm,其显微硬度值为20～25kgf/mm2。新水泥石与自然骨料界面区的厚度约为50-70μm,其显微硬度值为40～45kgf/mm2。X衍射试验发现,这两者界面区的水化产物类型相似,然而在水化产物的数量上有一定差异,水化产物的数量在一定程度上影响着界面过渡区的厚度和显微硬度值的大小。扫描电镜试验发现,各类界面过渡区大部分区域连接紧密,但仍有部分区域存在孔洞,结构疏松,旧水泥石结构致密,旧碎石骨料中有微裂缝的存在。界面过渡区的宽度、结构连接疏松或是致密及显微硬度值的大小都在微观上影响着再生骨料混凝土的力学性能。三、对圆柱体中再生骨料进行了形态分布测试。测试结果发现,在再生骨料替代率为50%的前提下,再生骨料最大粒径为20mm及35mm的两种试件,再生骨料在圆柱体中的分布并没有因为再生骨料密度及形状与自然骨料的不同而在试件中出现明显的分层现象,再生骨料和自然骨料呈随机分布状态。
[Abstract]:From the point of view of sustainable development, processing waste concrete into recycled aggregate concrete for recycled aggregate concrete can solve the problem of coordinated development between aggregate resources and ecological environment. Because of the different sources of recycled aggregates and their own unique properties from natural aggregates: high porosity, high water absorption, low density, low firmness and low wear resistance, The performance of recycled aggregate concrete is very different from that of natural aggregate concrete. In this paper, the properties of recycled aggregate concrete are studied from the macro point of view, combined with the microstructure and hydration products of the interface area of recycled aggregate concrete. The main contents are as follows: Firstly, the basic mechanical properties of recycled aggregate concrete with different recycled aggregate replacement ratio were tested. It is found that the cube compressive strength and the axial compressive strength of the recycled concrete decrease with the increase of the replacement ratio of recycled aggregate, and when the replacement ratio of recycled aggregate is less than 50, the compressive strength of the recycled concrete decreases gradually. The positive and negative effects of recycled aggregate on recycled concrete are maximum. The elastic modulus of recycled concrete with different recycled aggregate substitution ratio was tested. It was found that the elastic modulus of recycled concrete decreased with the increase of recycled aggregate replacement ratio. Secondly, the microhardness, scanning electron microscope and X-ray diffraction of the interface zone of regenerated aggregate were measured. The results show that there is a "film" in the interface area between new and old cement stone and between new cement stone and natural aggregate, and the thickness of this layer is about 20-40 渭 m, and its microhardness is 20 ~ 25kg / m ~ (-2). The thickness of the interface region between new cement stone and natural aggregate is about 50-70 渭 m. The microhardness of the new cement stone and natural aggregate is about 50-70 渭 m. The results of 40~45kgf/mm2.X diffraction show that the hydration products of these two interface areas are similar, but there are some differences in the quantity of hydration products. The amount of hydration products influences the thickness of interface transition zone and the value of microhardness to some extent. Scanning electron microscopy (SEM) showed that most of the interfacial transition areas were closely connected, but there were still holes in some areas, loose structure, dense structure of old cement stone, and microcracks in old crushed stone aggregate. The width of the interfacial transition zone, the loose connection of the structure or the size of the density and microhardness all affect the mechanical properties of recycled aggregate concrete microscopically. Third, the shape distribution of recycled aggregate in cylinder was measured. The test results show that under the premise of 50% replacement rate of recycled aggregate, the maximum particle size of recycled aggregate is 20mm and 35mm. The distribution of recycled aggregate in the cylinder does not show obvious stratification phenomenon because of the difference between the density and shape of recycled aggregate and natural aggregate, and the recycled aggregate and natural aggregate are randomly distributed.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU528

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