Which vantage to the use of the drainage asphalt?

The principal goal of road project designer is to insure roads' safety under all climatic conditions. Draining asphalts used for wearing courses contributes in reducing significantly accidents under rainy conditions. This research compares some drainage and impermeable pavements; particularly it is examined the behavior of the following pavements constituted from: only one porous layer, two porous layers, two reverse porous layers, an impermeable layer, assumed which reference. The varying parameter is the coefficient of acoustic absorption determined through the pipe of Kundt. It is interesting to notice that the drainage pavements not always provide good results. In fact, only for particular frequencies the drainage pavements furnish lower levels of the acoustic pressure (dB). The drainage mixtures, largely used in these last years, don't produce considerable acoustic advantages to the low frequencies and for reduced thickness, in comparison to the closed mixtures. If this aspect had to be confirmed by ulterior experimentation, we would conclude that the drainage asphalt must be used only along the highways and not in the urban roads. Therefore, in the project of the floorings so-called "porous" cannot be put aside by the importance of the frequencies.