【作者】 杨再富；

【导师】 钱觉时；

【作者基本信息】 重庆大学 ， 材料学， 2005， 博士

【摘要】 粗集料是混凝土的重要组成部分，可占混凝土体积的一半以上，但相当长时期以来，人们对混凝土组分的研究，一直将重点放在水泥的水化、混凝土外加剂和矿物掺合料方面，以期望更大程度地提高混凝土强度，而对于集料在混凝土中所起的作用，特别是从定量或半定量的角度，并没有系统的研究结果。作为混凝土两种主要构成材料的胶凝材料和集料，在胶凝材料的作用已发挥得比较充分的时候，集料的作用显得越来越重要。从两相复合材料角度分析，混凝土是一种非常特殊的两相复合材料，表现在粗集料和砂浆基体两相之间的性能存在差异，且这种差异随着龄期的变化而发生非常大的变化。基体的强度和弹性模量从零开始增加，到一定龄期后接近集料分散相，对于轻集料混凝土，基体的强度和刚度在一定龄期还将超过集料分散相。对于高强混凝土，特别是超高强混凝土这种变化将远比普通混凝土明显。尤其是这种差异随时间的变化对混凝土性能，特别是对混凝土的早期强度发展影响是比较大的。因此，研究两相之间强度和弹性模量的协调性及两相之间强度和弹性模量差异随时间变化对混凝土强度可能产生的影响具有非常重要的理论价值。从已有的报道看，国内外有关这方面的系统研究结果很少。 本文在教育部博士点基金项目《粗集料对混凝土强度影响的数值模拟》(20020611022)的资助下，首先研究了粗集料形貌、粒径、级配和用量对混凝土强度的影响，根据研究结果，考虑到粗集料的特性是多方面的，粗集料对混凝土的影响也是多方面的，因此选取碎石(卵石)、钢、砂浆、页岩陶粒、加气混凝土等五种强度和弹性模量差异较大的粗集料，在试验设计时尽可能保持其他因素相同，特别选择高强、中强和低强三种强度和弹性模量差异较大的砂浆基体，突出主要因素，试验研究集料-基体力学协调性对混凝土强度的影响。由于混凝土材料试验结果通常离散性较大，而且难以固定某一试验条件，变化因素之间难免形成交互影响，所以本文还运用数值模拟的手段，采用蒙特卡洛方法来实现混凝土材料的细观结构模拟，为了适应有限元分析和数值模拟的需要，本文还研究了Delaunay三角网格自动剖分方法，以就集料-基体力学协调性对混凝土强度的影响进行数值模拟。取得了如下创新性成果： 1)通过系统试验研究发现，粗集料与基体协调性对混凝土强度和强度发展具有重要影响，粗集料要在混凝土中起到增强作用，应在有约束的条件下，而且粗集料的强度和弹性模量应高于基体，但当粗集料弹性模量超过基体一定值后，不仅不能提高混凝土强度，而且抗折强度还显著降低。粗集料强度低于基体时，单更多还原

【Abstract】 As an important component, coarse aggregate accounts for more than one half in concrete. For a long period of time, the researchers have been focusing their studies on the hydration of cement, chemistry admixtures, and mineral admixtures as to increase the concrete strength. There are little systematic research results concerning the function of coarse aggregate, especially quantitative results. When the performance of cementitious materials has been developed extremely, then the coarse aggregate becomes more and more important. Concrete is a very special two-phase composite material, that is, there exists difference of the properties between the matrix and coarse aggregate and this difference would change markedly as the ages increase. The strength and modulus of elasticity of matrix increase from almost zero, then at a certain age up to those of the coarse aggregate, and even exceed for lightweight concrete. For high strength concrete, especially super-high strength concrete, this change will be more evident compared with ordinary concrete. These changeable differences mentioned above will affect the properties of concrete, especially the properties at early ages. So it is of great theoretical significance to study the matching-relation between the two phases on strength and modulus of elasticity and the influence on the performance of concrete caused by the matching-relation. From the present reports, there exists rare systematic research in this field.This paper is funded by Ministry of Education. It deals with firstly, the influence of coarse aggregate shape, max-diameter, size distribution, and content on the concrete strength is studied. From the results, we can see that coarse aggregate can affect concrete properties allround, on the premise of eliminating these factors reasonably and effectively, five types of coarse aggregate were determined and selected, including crushed limestone (pebble), steel aggregate, expanded shale and crushed aerated concrete with remarkable differences in strength and elasticity modulus. Then we studied the influence of the matching-relation between coarse aggregate and matrix on concrete strength in high, middle, low-strength mortar, and the same experiment was implemented on the condition of removal of restriction simultaneity. Secondly, in this paper, starting with the meso-structures of concrete, a mesoscopic numerical concrete model is constructed with Monte Carlo Method. And additionally Finite Element Method constructs Delaunay triangulation. We have achieved the numerical simulation of the influence of the matching-relation between coarse aggregate and matrix on更多还原