ABSTRACT
Porous asphalt (PA), as a wearing course in road construction, has advantages concerning noise reduction and drainage compared to common pavements because of the high void content. In this paper, the hydrological ‘linear reservoir’ model approach is used to analyse and describe the drainage behaviour of porous asphalt as a whole – from infiltration to discharge. This approach includes time-dependent runoff, runoff delay due to retention and the development of discharge rates depending on water stored in the porous asphalt structure. Based on experiments, the storage constant K, describing the model parameter of linear reservoirs, is calculated and compared for different porous asphalt structures, soiling states and amounts of retained water within the porous asphalt structure. It can be shown that higher rainfall intensities and coarser mix designs lead to a lower value of K, which indicates a faster outflow. The different soiling states do not show a significant effect on the storage constant K. The influence of retention capabilities – especially the amount of undrained remaining water volume – on the drainage behaviour in general and the parameter storage constant K are discussed as well. Higher retained water volumes lead to decreased values of K.
Acknowledgements
The work underlying this study was carried out under the research grant number FOR 2089, on behalf of the grant sponsor, the German Research Foundation (Deutsche Forschungsgemeinschaft, DFG). The described soiling and raining experiments have been done in a sub-project of the joint project ‘Leiser Straßenverkehr 2’ on behalf of the German Federal Ministry of Economy and Technology.
Disclosure statement
No potential conflict of interest is reported by the authors.