Functional Characteristic of double draining layer flexible pavements

The main characteristic of double draining layer flexible pavements is the use of different gradations of aggregates for the different layers, according to the specific task that each layer has to perform. Strong basaltic aggregates that can resist the stresses produced by traffic are used for the top layer, whereas calcareous aggregates that are ideal for open mixtures with good draining characteristics are used for the bottom layer. The function of the top layer, which has a higher density, is to filter surface dust and impurities and thereby protect the bottom layer, which truly performs the draining action. The results of an experimental study of such a mixture are presented. In particular, analysis results of permeability testing indicate that a double layer system provides excellent permeability coefficients and performances that are similar to those of a traditional single draining layer mixture. In addition, the results of mechanical characteristic tests performed show excellent resistance values for both bottom and top layers