ABSTRACT
This study evaluates the effect of natural weathering on the colour changes of asphalt. Blue coloured asphalts specimens were manufactured in the laboratory using a synthetic clear binder and three types of blue pigments of different composition. Coloured asphalts specimens were exposed to local weather conditions for over three months. Colour measurements were carried out using a spectrophotometer and the changes in colour were evaluated using internationally recognised colour parameters. It was found that exposure to natural weathering for a relatively short period of time (98 days) had a significant effect on the colour change of the blue asphalts studied. Sunlight and also local weather conditions such as temperature and humidity (dew) are believed to be responsible for these changes in colour. The variation in colour due to weathering was also greatly affected by the type of blue pigment, the blue asphalt produced with the pigment in pellet form was the least susceptible to weathering.
