Laboratory simulation of the clogging behaviour of single-layer and two-layer porous asphalt

The permeability of porous asphalt (PA) reduces after a few years in service due to clogging. The two-layer porous asphal (TLPA) was developed to mitigate this problem. This paper presents a laboratory-simulative clogging test of single-layer and TLPA using a falling-head water permeameter. The resistance to clogging of the PA specimens was evaluated by subjecting specimens to five clogging and cleansing cycles. All clogging tests were carried out at an ambient temperature. To evaluate the effects of temperature on clogging resistance, the clogging test procedure was also conducted on selected specimens but conditioned at 10°C, 30°C and 50°C. The test results showed that a significant permeability loss took place during the first few clogging and cleansing cycles, beyond which it asymptotes. The TLPA specimens can better resist clogging compared with the single-layer PA specimens. Binder content significantly affects clogging behaviour, while specimens conditioned at higher temperature were more susceptible to clogging compared with specimens conditioned at lower temperatures.