CHROMATIC AND RHEOLOGICAL CHARACTERISTICS OF CLEAR ROAD BINDERS

Clear asphalt pavements provide specific functional characteristics to improve safety and climatic conditions in urban areas. The technological development of clear pavements is referred to the formulation of special binders with particular chromatic characteristics. The research reported herein deals with the evaluation of three clear binders with different chemical formulations, and it has the aim of establishing their effectiveness in terms of mechanical properties and chromatic characteristics. Mechanical properties were analyzed by rheological methods. In this case all clear binders were found to have specific dependence on stress levels, time and temperatures. Moreover, different behaviors emerged depending on the chemical origin of binders. Chromatic characteristics were quantitatively evaluated by means of a digital image analysis. RGB as well as HSB (hue, saturation and brightness) models were used to determine and compare the chromatic performances of the three binders. The stability of the chromatic characteristics was also estimated using laboratory aging process. Relations were found between the chemical origin of the clear binder and its chromatic performance.