Monitoring hot mix asphalt temperature to improve homogeneity and pavement quality

This paper describes how controlled compaction practices lead to better quality asphalt. Therefore, it is important that during compaction operations the mixture is at a suitable temperature in order to achieve the specified degree of compaction. The University of Twente’s Asphalt Paving Research and Innovation unit’s main aim is to professionalize the road construction industry. One of the focus research issues is developing a deeper understanding of the Hot Mix Asphalt (HMA) cooling process and the variation in the mix temperature during compaction and laydown operations. Temperature measurement has become easier over the last decade due to the development of new infrared cameras, line scanners and sensors. The authors used this new technology to study asphalt temperature characteristics on test sections constructed in 2007 and 2008. It provided several insights into the cooling and variation in temperature of some asphalt mixtures used in The Netherlands. This paper presents and discusses the temperature measuring equipment used and the techniques applied to analyze and visualize the temperature data. The trials show that asphalt surface temperature is a good indicator of temperature homogeneity and process control. Also, that contractors will pay more attention to enhanced integration of HMA temperature as operational parameter in the compaction process given that the measurement technology is now easily within their reach. In the future, the authors expect a revival of research into cooling processes of HMA.