| The liquid rubber based concrete (LRBC) is a new kind of concrete-like composite in which the matrix is the liquid rubber substituting the conventional cement mortar. Comparing with asphalt concrete or cement concrete, LRBC has significantly different mechanical properties, which induces it to be a great potential high-performance pavement material. Currently, the investigation of the new concrete is just beginning, and plenty of testing and optimization works should be done before it present in engineering applications.The uniformization method has been widely used for depicting the material properties such as elastic modulus, Poisson's ratio etc. Anyhow such uniformization method is hardly used to predict the failure properties. The deformation and failure features of the meso-structure under loading are keys for the investigations of the failure mechanism and the further improvement of mechanical properties of the new material. The study of the failure process of the concrete-like materials is a very complex and challenging task, the investigation of the deformation and failure fectures of the LRBC specimen has significant academic and engineering values not only for investigating the failure process and mechanism of concrete-like materials but also for the optimization of the new concrete.In the present paper, the new concrete is modelled as a three-phase composite consisting of aggregate, liquid rubber matrix and interface between the aggregate and the liquid rubber matrix. The interface is regarded as an independent material with given geometry and mechanical properties. The bonding properties between liquid rubber and stone are given by tests. The influence of the interfacial thickness on the mechanical properties were studied and compared with experimental results to give a reasonable value of the thickness of the interfacial transition zone. Commercial procedure LS-DYNA is used and the effects of the loading rates on the numerical simulation results were investigated and compared with the experimental results to identify the just one of the loading speed which ensure the simulation results accurately and increase calculation efficiency at the same time.For the discreteness of macroscopic mechanical properties of concrete-like material, six samples with same meso statistical parameters of the aggregate geometry were investigated to study the discreteness of the macro properties of the material. From the study it is found that the random distribution of aggregates is one of the reasons why different specimens have different mechanical properties while they have same aggregate ratio, same grading and even same meso-statistical parameters. Besides, the failure process and fracture features were compared among the samples with different meso-statistical parameters of aggregate geometry. The numerical results derived the influences of the aggregate geometry on the tensile and compressive strength, the meso-scopic deformation and failure features of the LRBC. By the numerical analyzes, for LRBC, clearly, it has a group of meso-statistical parameters of aggregate geometry which will lead to the best material properties.Specimens with same aggregate ratio but different aggregate sizes were tested, and the influences of the aggregate size on the mechanical properties were investigated. It confirmed the effects of the gradation on the macro-properties of the concrete-like materials. Based on the traditional grading theory, a series of aggregate gradations were designed and for each grading three specimens were constructed. Static tensile and compressive tests carried out and the influences of the aggregate grading on the mechanical properties were studied. This method should give some help for the grading optimization of the new contrete.The deformation and failure factures of the meso-structure of the new concrete under dynamic compression were simulated successfully, and the failure factures, inertial confinement effects and strain rates effects were investigated simultaneously. |
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