Research Of Interface Layer Features Based On The Mesoscopic Model Of Concrete Random Aggregate

Concrete as a kind of heterogeneous and multiphase composite materials is widely used in practical engineering, the traditional study of concrete are mainly composed of macroscopic test, which simplifies the concrete for the homogeneous material, and gets various mechanical thermal parametersthrough test research, but the macro test always spend a lot of manpower, material and financial resources, and the results are often influenced by many environmental factors that make larger error. To study the damage and fracture process of concrete from macro scale to mesoscopic scale now,with the rapid development of the present computer technology, using the numerical simulation method to explore the macroscopic level of concrete mechanics problem has become a growing trend.Research is based on mesoscopic level, treated concrete as three-phase composite heterogeneous materials which consisted of aggregate, mortar and interface layer. Combining the geometric and statistical theory, based on the Monte Carlo method to establish models of concrete random aggregate, based on the MATLAB software to write the three different shapes of round, oval, and polygon models of two-dimensional random aggregate, put forward to the area of share to control the generation ofaggregate model, and respectively generate aggregate model with 40%,50% and 60%content and combine with AUTOCAD software to extract the aggregate boundary.Considering the interface layer’s weakness in concrete three-phase material and the study of characteristics of interface on the mechanical properties of concrete, author respectivelyset up aggregate model with different shape or different interface layer thickness or aggregate content, based on ANSYS computing platform, establishing the model of numerical experiment of uniaxial compression. After analysis and calculation: aggregate content is higher, the compressive strength of concrete will reduce, when aggregate content increase 20%, the compressive strength of concrete reduce about 10%rate. Under the same aggregate content, polygonal aggregate has the highest compressive strength, the average 18.4% and 8.0% higher than the circular and elliptical aggregate model. Under the condition of the same aggregate content, when the interface layer thickness increases, the compressive strength of the model has a small cut. Through the model of the final failure pattern figure proves the damage of concrete begins interface layer and continuously extends to form the macroscopic crack in the end.