| In recent years, with the developing construction of the national highway network, the demand for road construction materials is enormous. In China, since the founding of the country, concrete construction projects has gradually reached the lifetime and need to be reinforced or demolished, which will cause a lot of construction waste, including waste concrete. And because of the amount of scrap automobile tires growth year after year, which resulting in a great waste of the waste tire rubber and it has great influence on the environment. Therefore, the current scarcity of resources, the recycling of waste concrete and waste tire has become a serious problem to be solved in our country.The mechanical properties of concrete will be improved when the waste rubber has been incorporated into the concrete. And it has been greatly valued that the waste rubber is added into the asphalt concrete and cement concrete to produce the rubberized concrete as road construction materials. The rubberized concrete is lightweight and high elastic, which has good ductility and toughness, meanwhile it has superior performance on crack resistance, impact resistance and shock absorption. The application of research on the rubberized concrete as pavement materials has gradually become the hotspot in the new concrete field. Not only it can re-use of resources, reducing environmental pollution, which is a good solution on the "black pollution" of the serious ecological problems; but also it will be improve the structure and performance properties of concrete pavement, which is greatly improving the ductility and impact toughness.In this paper, rubber modified recycled aggregate concrete (RMRAC) is for the study object, and it is the use of variable cross-section Φ74mm split Hopkinson pressure bar (SHPB) device to study the RMRAC dynamic mechanical properties under four strain rate, the main work of this study is as followes.(1) The fine aggregate of the recycled aggregate normal concrete (RANC) is volumetric substituted by the recycled rubber powder in order to produce RMRAC, which the substituted volume fraction includes10%,20%,30%and40%, and the rubber powder sizes are5mesh,20mesh and60mesh respectively. It is using the material testing machine MATEST24048to test the compressive strength and flexural strength of RMRAC, which in oder to obtain the influence of rubber content and particle size on the strength of RMRAC, and get the brittleness coefficient of RMRAC;(2) Using the copper plate with size of Φ10×1.5mm as the shaper, the initial waveform will be shaped, which it can obtain the load pulse with longer rising time and weaker oscillation to meet the basic assumption of stress uniformity, and making the results more reliable;(3) By SHPB test under four strain rates corresponding four controlled air pressure (0.3MPa,0.4MPa,0.5MPa and0.6MPa), obtained the stress-strain curves of specimens. And it will be studied that the influence of rubber particle size, rubber content and strain rate on RMRAC dynamic compresssive strength, dynamic increase factor (DIF) and toughness index.The results show that, under the dynamic loads, it is similar to normal concrete that RMRAC has strain rate enhancement effect. While it is reducing the static and dynamic strength of RMRAC as the incorporation of waste rubber powder, the toughness and the impact resistance of RMRAC will be improved greatly. |
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