| Hot recycling technology of asphalt pavement can make full use of the old asphalt pavement materials, save resources, protect the environment, so it has been more widely used in the conservation of the asphalt pavement. Recycling asphalt pavement material (RAP) is one of the ingredients of recycling asphalt mixture. Hot recycling in plant projects generally use cold milling RAP. The characteristics of RAP have important influence on the performance of the recycling asphalt mixture. Also, the characteristics is the important basis of mix proportion design of recycling asphalt mixture. Based on this, a comprehensive analysis of RAP in different layers was made including the performance of asphalt, gradation and aggregate performance. The asphalt mortarand mixture with different dosage of asphalt were analyzed, including the performance of high temperature stability, low temperature crack resistance, water stability and fatigue resistance. The influence factors of RAP were analyzed, the reasonable evaluation methods of RAP were explored and the relationship between the recycling mortar and the performance of recycling asphalt mixture was studied.The top layer and the middle layer of the cold milling RAP sampled from the Ning-Jing-Yan highway were chosen as the research object, and the experimental method of SHRP plan was used in the research. Through regular performance, dynamic shear rheological (DSR) and low temperature bending beam rheological (BBR) tests, the recycling asphaltis were evaluated for the three major indexes, i.e., the high temperature performance, low temperature performance and fatigue performance.Secondly, in view of two different grading (AK-13, AC-20), the moisture content, oil stone ratio and gradation were analyzed. Divid RAP into the coarse aggregate and asphalt mortar part, the performance of the recycled aggregate was analyzed, including the physical constants of coarse aggregate, abrasion resistance performance of the edges and corners and fine aggregate sand equivalent, check whether the indicators meet the specific requirements and construction. The test data and analysis of AK-13 and AC-20 and the decline rule between the basalt and limestone performance were compared.Then, different RAP blending proportion (100%,50%,30%,0) were studied through the indoor experiment including the high temperature stability test, low temperature performance of asphalt mortar, water stability and fatigue resistance in order to study the relationship between the performance of the asphalt mortar and mixture.After that, compare the milling RAP, new asphalt mixture and the newasphalt mixture with the same grading as the RAP in the performance of high temperature stability, low temperature performance of asphalt mixture, water stability and fatigue resistance, analyzing the characteristics of the decay of the RAP and the influence factors of the RAP. The reasonable evaluation methods of the RAP were explored.Finally, compare the corresponding performance of mortar and mixture with different RAP blending proportion, exploring the relationship between them, including high temperature, low temperature performance and fatigue resistance performance, in order to explore the effect on characteristics of RAPand reworked material, providing a reference of the influence for design of the reworked asphalt mixture. |
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