LABORATORY EVALUATION OF MODIFIED POROUS ASPHALT MIXTURES

Porous asphalt mixture (PAM) is mainly applied to the surface drainage layer on high-speed trafficked highway pavements because it has many application advantages such as : noise reduction and safety during rainfall due to its open structure water is stored and moved horizontally within the layer which reduces splash and spray effects and thus increases the visibility of drivers during rainfall. On the other hand the major disadvantage of porous asphalt layers are low stiffness , high rutting and durability .The objective of this study was to compare the influence of two modifier types (styrene-butadiene-styrene [SBS] and propylene modifier [PP]) on a porous asphalt mixture performance . The PAM evaluation was based on air voids, asphalt flow drain down, and abrasion resistance at the mix design step. The mix performance has been investigated by permeability, moisture susceptibility, and rutting. The test results emphasized the importance of using the modifier in in minimizing the abrasion loss, reducing rutting and enhancing the durability of the PAC mixture. Porous asphalt mixtures prepared with 5 % SBS modifier were the most effective at increasing the abrasion resistance and reducing rutting; and the PP had no effect on the mix strength.