Experiment And Numerical Simulation Of Effect Of Coarse Aggregate On Concrete Strength

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...