Water damage of asphalt pavement prevention and control method
Water damage of asphalt pavement prevention and control method
Water damage of asphalt pavement is derived from bitumen membrane from the surface of the Strip which is water involved on the interface between bitumen and aggregate, changing the relationship between asphalt, aggregates and water caused by. So, the key to prevent water damage is to be resolved through three ways: ① prevention or reduction of water entering the asphalt mixture, not intrusive to the asphalt-aggregate interface to ② improve the adhesion of asphalt and aggregates, improving bond strength between aggregate c control of pavement cracks and water infiltration.
1, according to the first approach, asphalt mixture gradation is the most important factor, in particular reduced porosity. However, this is limited. Ordinary gradation asphalt mixtures, largely suspended in the asphalt of coarse aggregate in mortar, and porosity of void fraction is less than the detection limit (2%-4%), the asphalt in the summer when thermal expansion without proper clearance to go, it is easy to float (oil pan), jostle, push the rutting liquidity deformation of mixture.
Problem now is the voids of asphalt mixtures are often larger, providing water to places within the asphalt mixture. Most of our current terms of Expressway asphalt pavement, and voids has two levels: 1.First is the antiskid surface, for anti-sliding surface structure depth needs necessitated the gap had increased to 4%-8%, whether under heavy rain, always within the asphalt mixture is soaked with water, which is now graded against sliding of Achilles. One way to solve conflicts between anti-sliding performance requirements and water stability is that the use of stone matrix asphalt mixture (SMA) structure, SMA is a filling of gap-graded broken stone matrix asphalt mixtures composed of skeletons. Because of gap-graded gravel formation skeletons at the surface caves, texture depth, and had good antiskid performance. And because the fully populated matrix asphalt, asphalt mixtures voids within the very small (2%-4%). SMA is basically impervious advantage can significantly improve the water stability of asphalt pavement; the same problem also happens on the bottom floor, now universal design for voids larger type II asphalt mixtures, such as AC-25 or AC-30 structures of type ⅱ is currently adopted. Surface layer for type ⅰ in dense graded asphalt mixtures, although more difficult to enter from the upper layer of water surface, but in fact there is always a small amount of infiltration, sometimes pavement with cracks, water is inevitable, not to mention the moisture from the grass-roots up into the asphalt mixture. Especially in winter frozen in the process of accumulation of moisture by capillary action up, until the spring thaw season, melting of excess moisture naturally stuck in the holes of the bottom layer mixture. Type II asphalt mixture of pore water in the long-term under traffic loading, dynamic water pressure to asphalt membrane adherence of aggregates is a very big threat. So, actually, for asphalt pavementWater damage destroyed lots from the layers below to begin. We see loose, pit in the surface layer, layer already loose. Local cracks of intensive excavation from the surface, one can often see, bottom layer of asphalt mixtures have stone is stone, asphalt bitumen, clearly, this is the spring melt season often large cause of pothole damage.
