Development of Special Additives for Highly Durable Asphalt Pavement
摘要
The pavements constructed at container yards, factories, and bus stops are exposed to severe conditions, unlike roads under normal conditions, because vehicles with heavy wheel loads, such as trainer trucks or buses, pass over them. In such pavements, the cement concrete pavement or semi-flexible pavement filled with cement milk in the air voids of a porous asphalt mixture, which have excellent resistance to rutting, are generally used. However, these pavements require time for the cement to cure and time to inject cement milk after laying the porous asphalt pavement. Therefore, early opening to traffic is difficult on these pavements. For this reason, it is not easy to construct these pavements in places with time constraints. Therefore, we have developed a highly durable asphalt pavement that has the same resistance to rutting as semi-flexible pavement and allows for early reopening to traffic. The newly developed pavement is an asphalt mixture that combines a conventional dense-graded asphalt mixture with a plant-mix type special additive so that it can be manufactured and constructed in the same methods as a traditional mixture of asphalt, and traffic can be reopened under the same conditions. The special additive shows thermoplastic properties, so it hardens as the temperature drops. In other words, the special additive exerts its strength when the temperature at which the pavement can be opened to traffic, so the long curing time like cement concrete, is not required. This study introduces pavement repair work at a bus stop where route buses stop repeatedly as an example of construction in Japan. As a result of applying the highly durable asphalt pavement using our special additive to bus stops instead of semi-flexible pavement, the construction time was reduced by 20%, and the road surface remains in good condition with no rutting even after 4.8 years.