The Rearch On Design And Construction Process Control Technology Of Beijing-Shanghai Freeway Asphalt Concrete Pavement In Tai'an Province

Water damage on highway asphalt pavement is a typical problem in China and all over the world. The highway development in China began about half century later when the rich countries in the west did, and so was the study on highway asphalt pavement water induced damage. For this reason and since prevention measures were imperfect, early water damage occurred frequently. China took a great economic loss and negative social influence. Therefore, it's duty of transport operator to study of water damage on highway asphalt pavement from design, structure, mixture ratio and drainage.The prerequisite of water damage on highway asphalt pavement is water. The causes of water damage can be classified into these categories: permeable upper surface course, water-storage mid-lower surface course, impermeable base course, overloaded vehicles and bad condition of environment. All these factors make water damage become possible. There are voids originally in asphalt mixture, and other factors make them bigger, such as poorly-graded construction materials, low degree of compaction, mixture segregation. Since highway base course in China was semi-rigid and impermeable, it brought about permeable upper surface course and water-storage mid-lower surface course. There would be early disease in highway surface such as road track, pits, cracks, jack and so on after it's open to traffic two or there years later since it withstood heavy traffic and long-term effects of repeated wheel load. Except for the external conditions, another important aspect of asphalt concrete water diseases is an internal factor. The immediate consequence of water disease is that adhesion and cohesive forces between asphalt and aggregate lost and asphalt peels off from the aggregate. It's a complex physiochemical process that asphalt and aggregate conglutinate and peel off which haven't been understood and grasped well yet.In this article, the formation condition and start forming mechanism were analyzed, and prevention measures against spell between asphalt and aggregate were studied in order to improve water stability of asphalt mixture. The measures improving adhesiveness between asphalt and aggregate included three parts: using high-quality aggregate, using low needle penetration asphalt and adding additive. High-quality aggregate and low needle penetration asphalt can be controlled in the progress of selecting raw materials and it need a large number of experimental verification and engineering practice to definite the ratio of additive.We can draw this conclusion from engineering practice that amine as well as hydrated lime can improve water stability of mixture and a series of short-term and long-term aging tests such as mixing with hydrated lime, mixing with amine and control group of concrete. Amine anti-stripping agent can improve adhesion between asphalt and aggregate through reduce asphalt surface tension and increase wetness of aggregate surface. It performed well in the beginning but poor in the long-term. Asphalt mixture mixing with hydrated lime performed better than that mixing with amine in the long run. Further, mixing with amine can strengthen stability in high temperature, crack resistance in low temperature and anti-fatigue properties. For example, asphalt mixture water stability can be effectively improved while adding one percent hydrated lime.Pavement cracks (including horizontal cracks, longitudinal cracks, chapping, etc.) is an important path of water into the structure, especially reflection cracks caused by shrinkage cracks in semi-rigid base. It can effectively prevent the occurrence of reflection cracks when large size asphalt mixture flexible base is used. High-temperature stability, anti-fatigue properties, permeability and adhesion properties of big grain diameter modified asphalt was individually analyzed through wheel tracking test, three points division fatigue testing, permeability test and modified asphalt test. Then, anti-reflection cracks ability of mixt big grain diameter asphalts was analyzed and compared with several other ures. Preliminary analysis can be drown that big grain diameter asphalt is a good flexible base with fine high temperature stability, low temperature crack resistance stability, anti-fatigue property, permeability and some resist reflection crack ability.Several conclusions can flow from overhaul practice of Taian section, the Beijing-Shanghai Expressway in recent years, that big grain diameter asphalts using as base can resolve or delay the occurrence of early asphalt pavement water damage if mixing one percent hydrated lime as anti-stripping agent , adopting appropriate aggregate sizes and well compaction.