The Research On Pavement Maintenance Technology Of Beijing-fuzhou Expressway Shandong Segment (k222-k246)

Large-scale high grade pavement, especially asphalt pavement prevailed from the 1990s. Many high-grade asphalt pavements are in the stage of medium and heavy maintenance after 2000. We face increasingly heavy task of highway maintenance. On the one hand, the high price and short supply of pavement materials is a problem, on the other hand, huge amounts of waste and scrap are difficult to be piled up and they will cause heavy pollution to soil and water source[1]. It is essential to select appropriate maintenance mode to ensure pavement quality, save cost and reduce environmental pollution. In recent years, recycling utilization of second-hand asphalt pavement has developed rapidly in China and drawn attention of many parties. Now, there are mature technology and equipment for widespread use of this method for pavement maintenance.Hot in-place recycling of asphalt pavement is studied in this paper. Graduation of former pavement is analyzed, so are those of new additives and mixture, and all test indexes of new pavement are analyzed. Main control points of Hot in-place recycling are graduation analysis of former pavement, design of mix proportion of recycled asphalt mixture, recycling heating, control of milling and planing, regenerant amount, mixture blending flow, compaction control. During construction, percent of new additives and regenerants are generally controlled within 10%--30% and 2-5‰. Under required heating temperature, all materials are fully used and planeness, water permeability coefficient, void ratio and asphalt content of new pavement meet requirements. Under normal air temperature, 120m one-lane can be paved within one hour, which embodies the practical prospect of Hot in-place recycling.aConstruction using Hot in-place recycling in Shandong province k222—k246 section of Jing-Fu freeway in recent two years are analyzed. The detection of pavement aging and new pavement shows that the recycling pavement meets standard requirements. Thermal recycling facility of this project uses hot air circular heating mode for the first time to heat and mill layer by layer. Enough heat energy is supplied to pavement and asphalt in pavement is effectively protected from aging and decomposition. Two-stage mixing system ensures the full mixing of new and old mixture and the temperature during paving. The pavement planeness is greatly improved by the independent paving system. Hot in-place recycling equipemnt and technolgy are continuously renovated and they are more applicable for high grade asphalt pavement.