Ice Formation and the Effectiveness of Deicing Agent on Porous Asphalt and Stone Mastic Asphalt

Porous asphalt (PA) and stone mastic asphalt (SMA) are widely used by many transportation agencies and public works officials. However, the best winter maintenance practices for PA and SMA are unclear and generally unquantified. In this study, laboratory tests under controlled, artificial wintry conditions were conducted to evaluate the winter performance of PA and SMA. The test results are summarized as follows: (a) PA was effective at reducing the amount of water that formed an ice layer on the pavement surface and the thickness of the ice layer. SMA had intermediate effects between those of dense-graded asphalt (DGA) and PA. (b) The rate of decrease in ice layer thickness was found to be the largest for PA; that for SMA was intermediate between those for DGA and PA. (c) The features described above were dependent on the temperature and the amount of water applied. Analysis of the experimental data found that the coefficient of friction had a strong correlation with ice layer thickness, and the ice layer thickness was predicted from mean profile depth, permeability, temperature, water dosage, deicer application amount, and number of wheel passes. Accordingly, the study suggests the possibility of determining the ice layer thickness at which friction-generating contact between the pavement and the tire is reduced and how much deicer is needed to maintain a certain level of service based on pavement type, weather conditions, and traffic volume.