Research On Mineral Aggregate Migration Rule And Gradation Optimization Design Of Hot Recycled Asphalt Mixture

China’s highway construction has conversed into the stage that maintenance is as important as construction from the stage of building up only. In the process of asphalt pavement reconstruction and maintenance, a large amount of waste asphalt pavement material has been produced. Asphalt pavement recycling technology, especially the hot mix plant regeneration technology, can effectively recycle the old asphalt pavement materials, reduce asphalt, stone and other materials, and avoid environmental pollution and waste of resources. The technology has been widely used at home and abroad. In the hot mix plant regeneration, the migration status of old mineral aggregate particles has important implication on grading design and hot regenerated asphalt mixture road performance. Under the support of Shandong Province Science and Technology Innovation Project: “Long-term road performance and application technology of Hot Mix Plant Recycled Asphalt Mixture(2015B02)”,this paper combined with physical project, the measuring method of the old mineral aggregate particles migrating status, and their migration rules and hot recycled asphalt mixture grading optimization will be studied systematically and thoroughly.With laboratory experiments and theoretical analysis, the measurement method of the old mineral aggregate transition state in the thermal regeneration is proposed, which includes interior RAP simulation preparation, hot recycled asphalt mixture mixing, separation of old and new mineral aggregate, analyze and calculation, etc. Meanwhile, technical indicators evaluating different specifications of the old mineral aggregate particles migrating status are put forward.With four kinds of RAP content(20%、30%、40% and 50%) and the measuring method, migration status of the old mineral aggregate particles of various specifications(≤1.18mm) are determined in thermal regenerating asphalt mixture.Considering engineering practice, heat recycling asphalt mixture of different RAP content has been designed in mixing ratio through lab tests. Based on experiment results of migration state of old mineral aggregate particles in recycling process, grading design is optimized. Furthermore, thermal recycling mixture grading design optimization are obtained based on old mineral aggregate transition rules. High-temperature stability, low-temperature performance and stability in water of hot recycling asphalt mixture after grading design optimization have been measured and analyzed.In S243 Mingtai rehabilitation project, according to regenerated heat asphalt mixing ratio design results, hot recycled asphalt pavement were paved, shaping quality were tested. Eventually, technology of hot recycled asphalt mixture production and construction were summarized and obtained integrally.