Monitoring the temperature gradient of pavement structure layers and its effect on the structural behaviour helped to establish a fundamental understanding of the magnitude and impact of these variations on the pavement response to different loading conditions. The performance of pavements clearly reveals the need to properly measure the distribution of stresses and strains within road layers over a period of time taking into account the effect of extreme temperatures. The adverse effects of traffic speed during hot weather conditions on the structural behaviour of the flexible pavement are briefly discussed and possible recommendations to overcome these effects. Structural data including stresses and strains were collected under the action of external loads applied by a calibrated test trucks. To mimic the effect temperature extreme events on the flexible pavements, the study was carried out on flexible roads immediately after the construction at 51o C (truck impact test) and 44o C (truck creep test) and after one year at normal operating temperature (20o C).
The field results showed unprecedented high stress and strain levels caused by low asphalt stiffness when the asphalt mat temperature is above a normal operating temperature. Traffic-induced stresses and strains transmitted through the asphalt concrete layer to unbound materials of the asphalt concrete are directly influenced by the stiffness. The impact test using a truck speed lower than 25 km/h resulted in a very high truck pressure impact. This study confirmed that most of pavement performance problems occurred at locations were buses frequently stopped and areas close to traffic signals. This finding highlighted the importance of traffic speed impact, extreme hot weather events and the interaction of both.
Key words: Temperature effect; flexible pavement; stiffness of asphalt concrete; structural behaviour