The most commonly used surfacing material for roads in Malaysia is asphaltic concrete. Other materials used include macadams, stone mastic asphalt, porousasphalt and surface dressing or chip seals. Unlike asphaltic concrete, porous asphalt is relatively new in the Malaysian context. Porous asphalt was developed in the 1950’s on British airportrunways to improve the safety of fast moving aircraft traffic. The material later found its usage for roads on similar traffic safety grounds. A characteristic feature of porous asphalt is its high voidcontent, typically in excess of 20 per cent. This stems from the aggregate gradation which consists of predominantly coarse aggregate fraction but lower sand fraction and filler proportions.
Totake advantage of its ability to eliminate ponding water, porous asphalt is normally used for the wearing course. As in conventional mixes, it supports vehicle loads and transfers them to the underlyinglayers though its structural contribution is low. Other terminologies associated with porous asphalt include drainage asphalt, whispering asphalt, ecophalt, pop-corn asphalt or pervious asphalt.The terminology porous asphalt will be widely used in this thesis.
2. Problem Statement
Every year, the number of registered vehicles on Malaysian roads increases steadily. According to the HighwayPlanning Unit (2002), there are 12 million units of registered vehicles in the year 2002 which is about half of the total Malaysian population. The high increase in the number of vehicles annuallyhas partly contributed to the increase in the number of road accidents. However, there are also several pavement factors that have contributed to the increase in road accidents. Current pavement mixsuch as asphaltic concrete has been acknowledged for its ability and durability in terms of its life-span. However, on wet roads, this conventional material is undesirable to users in terms of...