Micro-structural properties of porous asphalt mixture

Abstract

In order to fully understand the properties of porous asphalt, investigation should be conducted from different point of views. This is from the fact that, porous asphalt mixture designed with the same aggregate gradation and air void content can give different infiltration rate due to the different formation of the internal structure. Therefore this study is carried out to investigate the micro-structural properties and functional performance of porous asphalt simultaneously. The aim is to develop imaging techniques to process and analyze the internal structure of porous asphalt mixture and compare to its performance. A few parameters were established to analyse the air void properties and aggregate interlock within the gyratory compacted samples captured using a non-destructive scanning technique of X-ray Computed Tomography (CT) throughout the samples. Four aggregate gradations used in different countries i.e. Malaysia, Australia, the United States and Singapore were adopted in this study for preparing the gyratory compacted sample. The samples were tested for resilient modulus and permeability. Quantitative analysis of the micro-structure was used to establish the relationships between the air void properties and aggregate interlock and the resilient modulus and permeability. Based on the results, it was found that the micro-structural properties investigated have successfully describe the internal structure formation and they reflect the results of resilient modulus and permeability. In addition, the imaging technique which include the image processing and image analysis for the internal structure quantification seems to be very useful and perform well with the X-ray CT images based on the reliable results obtained from the analysis