Air voids measurement on asphalt mixes section surface based on image analysis

Asphalt concrete is a porous and no uniform material; air void always plays an important role in asphalt concrete quality control. This study describes a new analytical method to quantify the air voids on section surface of asphalt mixes based on image analysis. This study establish a credible relationship of natural logarithmic between the micro index from this new measurement and traditional macro index of air voids and put forward a uniform method which can predict the percent air voids being suitable to various aggregates of asphalt concrete and easy to promote based on image analysis. This study also established a system approach to analyze the image features of air voids and defined the composition of the air voids features which are geometry, gray-scale and spatial distribution features. These image features of air voids can establish a quantized correlation with percent air voids or other macro index and can explain the phenomenon that some macro index conflict each other. It is necessary to study further into the micro level of air void properties; the image analysis technique provided in this paper will be a powerful too to study the features of air voids.