机制砂质量指标对混凝土性能影响研究
发布时间：2018-10-05 18:57
【摘要】：混凝土细集料需求量逐年增长,传统细集料——天然砂由于过度开采,品质下降、成本增加,因此人工破碎的机制砂的应用日渐广泛,也成为了当前研究的热点。本文对机制砂的颗粒形状、表面质地进行了量化表征;探究了机制砂的粉料含量和MB值对混凝土的综合作用;并对机制砂与河砂粒形差异对混凝土性能的影响进行了研究;通过测试机制砂、河砂混凝土的孔结构及界面过渡区微观结构、组成,对机制砂混凝土与河砂混凝土性能差异形成的机理进行了探讨。研究发现:采用图像分析与激光显微系统量化表征了机制砂4.75~2.36mm颗粒的粒形及表面质地:机制砂的圆度及长宽比均大于河砂,其颗粒为不规则棱角形、针片状含量高;在0.4μm光源下,部分机制砂试样的显微表面面粗糙度低于河砂,河砂的显微表面反而比一些机制砂更为粗糙;利用XRD定性分析机制砂75μm以上颗粒和75μm以下粉料的矿物组成,其组成只是在相对含量上存在一定差异。机制砂的粉料含量和MB值是一组相互关联的质量指标,不同MB值(0.5、1.0、1.4、1.8、2.2)下,混凝土坍落度达到最大值时机制砂的粉料含量都在10%~15%的范围内;高粉料含量(20%~10%)、低MB值(≤1.4g/kg),或高MB值(1.4g/kg)、低粉料含量(10%~5%)的机制砂都可以配制出性能指标良好的混凝土。在相同的颗粒级配和粉料组成下,机制砂不规则的颗粒形状对配制混凝土的工作性及抗氯离子渗透性能影响不大,此条件下颗粒形状圆滑的河砂反而获得了更高的抗压强度,机制砂不规则的颗粒形状并不是其配制混凝土强度高的主要原因,但却改善了混凝土的抗冻性及早期抗收缩能力,对后期抗收缩能力的影响较小。采用MIP及FE-SEM(EDS)测试了原状机制砂、原状河砂混凝土孔结构和界面过渡区微观形貌及组成。两者孔隙率相差不大,因此它们的氯离子渗透系数相近;原状机制砂混凝土孔隙更大,因此其抗冻及抗收缩能力较差;原状机制砂混凝土界面过渡区更为致密,元素分布均匀,无缺陷,因此其强度更高。
[Abstract]:The demand for concrete fine aggregate is increasing year by year. The traditional fine aggregate-natural sand has been widely used in the field of artificial crushing due to its overmining, its quality and its cost. Therefore, it has also become a hot research topic at present. In this paper, the grain shape and surface texture of machine-made sand are quantitatively characterized, the comprehensive effect of the content of powder and MB value of machine-made sand on concrete is explored, and the influence of the difference between machine-made sand and river sand on the concrete performance is studied. Through testing the pore structure and the microstructure of the interface transition zone of the machine-made sand, the formation mechanism of the performance difference between the machine-made sand concrete and the river sand concrete is discussed. It is found that the grain shape and surface texture of machine-made sand 4.75~2.36mm particles are characterized by image analysis and laser microscopy. The roundness and aspect ratio of machine-made sand are larger than that of river sand. Under 0.4 渭 m light source, the surface roughness of some machine-made sand samples is lower than that of river sand, and the micro-surface of river sand is rougher than that of some machine-made sand, and the mineral composition of machine-made sand above 75 渭 m and powder below 75 渭 m is analyzed qualitatively by XRD. Its composition is only different in relative content. The powder content and MB value of machine-made sand are a group of interrelated quality indexes. When the slump of concrete reaches the maximum value, the powder content of the machine-made sand is in the range of 10% or 15% under different MB values (0. 5 ~ 1. 0. 0 ~ 1. 4 ~ 1. 8 ~ 2. 2); High powder content (20%), low MB value (鈮，
本文编号：2254507
[Abstract]:The demand for concrete fine aggregate is increasing year by year. The traditional fine aggregate-natural sand has been widely used in the field of artificial crushing due to its overmining, its quality and its cost. Therefore, it has also become a hot research topic at present. In this paper, the grain shape and surface texture of machine-made sand are quantitatively characterized, the comprehensive effect of the content of powder and MB value of machine-made sand on concrete is explored, and the influence of the difference between machine-made sand and river sand on the concrete performance is studied. Through testing the pore structure and the microstructure of the interface transition zone of the machine-made sand, the formation mechanism of the performance difference between the machine-made sand concrete and the river sand concrete is discussed. It is found that the grain shape and surface texture of machine-made sand 4.75~2.36mm particles are characterized by image analysis and laser microscopy. The roundness and aspect ratio of machine-made sand are larger than that of river sand. Under 0.4 渭 m light source, the surface roughness of some machine-made sand samples is lower than that of river sand, and the micro-surface of river sand is rougher than that of some machine-made sand, and the mineral composition of machine-made sand above 75 渭 m and powder below 75 渭 m is analyzed qualitatively by XRD. Its composition is only different in relative content. The powder content and MB value of machine-made sand are a group of interrelated quality indexes. When the slump of concrete reaches the maximum value, the powder content of the machine-made sand is in the range of 10% or 15% under different MB values (0. 5 ~ 1. 0. 0 ~ 1. 4 ~ 1. 8 ~ 2. 2); High powder content (20%), low MB value (鈮，
本文编号：2254507
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