Recycled Asphalt Mixture Design Methods And Pavement Performance Based On The Recycled Coarse Aggregate

Road construction consumes huge amounts of natural aggregates every year, at the same time a large number of construction and demolition waste(C&D waste) is produced in our country. Most of C&D waste, such as waste concrete, brick, etc. after crushing process and grading can be reused as recycled aggregates. Road has multi-level and multi-structure features, the quality of the aggregate generally decrease with the decrease of road grade and the increase of structural depth. In this paper, through the study of recycled coarse aggregate(RCA) technical indicators, variability, previous process which affect its technical indicators, as well as involving the RCA for asphalt concrete design and the pavement performance, it provides experimental basis for the development of asphalt concrete with recycled aggregate and relevant technical standards or guidelines.Firstly, through testing and variability analyzing the technical indicators of RCA from recycled aggregate production line of Guanggang Xincheng, finding that the RCA has a low density, high water absorption, poor mechanical index and large variability. Then grinding and shaping the RCA under the laboratory conditions, analyzing the technical indicators and variability of the post-processing RCA, finding that grinding and shaping can effectively improve the quality of RCA.Based on the characteristics of RCA which has small bulk volume density and weaker particle content in cement mortar, proposing that the volume correction and the amendments of key sieve to adjust aggregate gradation of RCA asphalt mixture. Using the Marshall Test method to determine the optimum asphalt content. Analyzing the influence of the RCA to volume index of asphalt concrete, asphalt content, effective film thickness of asphalt and rubber powder ratio. The results show that with the increase in coarse aggregate content reproduction, the optimum asphalt content of asphalt concrete increases, effective asphalt content, film thickness and effective asphalt ratio varies little pink gum.Respectively using wheel tracking test, low temperature bending test, immersion Marshall test, freeze-thaw splitting test, as well as split test to study the influence of RCA for asphalt concrete temperature stability, low temperature crack resistance, water stability and mechanical properties. The results show that with the increase in coarse aggregate content reproduction, after dynamic stability of asphalt concrete to increase drop, low temperature cracking performance, water stability enhancement, splitting tensile strength decreased.