Effects of air void and porosity on moisture damage of Malaysian specialty HMA

Abstract

One of the main causes of distress in asphalt pavements is damage due to water. This causes related to many effects. The study evaluates different type of asphalt mixtures towards the resistance to moisture damage. The approach is to investigate the relationship between air void and porosity against the abrasion resistance and indirect tensile strength. The evaluation of such properties concentrates on the following three tests; porosity test, indirect tensile test (IDT) and CANTABRO test (CAT) .Three different wearing courses with modified asphalt which porous asphalt (PA),stone mastic asphalt (SMA) and gap-graded asphalt (GPA) that classified by (JKR/SPJ/2007) are studied. These three mixtures were designed by means of Superpave method to determine OBC. After that Specimens were prepared by means of Superpave Gyratory Compactor (SGC) and divided in two different subsets for controlled dry and wet conditioned testing and tested for water damage. Results provide relationship between porosity and air voids for PA mixture. In addition, study also able to establish good models for SMA and GPA mixes compared to other researcher (Walaa,2002). SMA and GPA mixtures (low porosity) showed less influence to moisture damage probably due to the reduce amount of penetrating water. The IDT and CAT are able to discriminate between mixtures of different porosity.