Clear Asphalt Mixture for Wearing Course in Tunnels: Experimental Application in the Province of Bolzano

Safety driving and reduction of environmental impact have gained a predominant role in the strategic project and design of infrastructures. One of the main effects of this new technical and political awareness has been the increase in the construction of coloured asphalt pavements (CAP). CAP consists of the same materials commonly used for flexible or semi-rigid pavements except for the wearing course that is manufactured using specific binders or pigments. The clear binders bring out the brightness and the natural color of aggregates, whereas the use of pigments allows a great number of chromatic variations of road to be obtained. The first applications of CAP were to define sidewalks, pedestrian areas, cycle tracks. In the last few years the development of proper binders has allowed using CAP also in heavy-traffic roads to help selecting lane, to reduce the environmental impact, to highlight the intersections and to improve safety in tunnels. Moreover, the use of clear binders exploit the reflection capacity of aggregates increasing the visibility during night and reducing the energy consumption for the lightning of roads or tunnels. The results showed in this paper are part of an overall experimental program, in collaboration with the Autonomous Province of Bolzano, on clear asphalt mixtures (CAM) for wearing courses. In particular a CAM, designed and laid down during the rehabilitation of an Italian tunnel, was subjected to the acceptance inspection, mechanical characterization and determination of photometric properties. Traditional and performance-based tests were carried out to determine the failure resistance, compactability, stiffness, abrasion resistance and water sensitivity of the CAM. Luminance and reflection properties of CAM were measured and compared with those of HMA in order to assess possible lighting benefits. A following in-situ monitoring of pavement performance will integrate the results obtained in laboratory.
Autori: 
Bocci M., Grilli A., Cardone F., Virgili A.
Anno del prodotto: 
2012
Societa' Italiana Infrastrutture Viarie - S.I.I.V. - Cod.Fis. 93024730421