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Abstract. In the present study, the effects of adding crumb rubber modifier from end of life tires on the mechanical, functional, acoustical and environmental properties of asphalt mixtures were investigated in situ. Four different dense mixtures, characterized by similar gradation curve and optimally designed in laboratory using the volumetric method, were laid on a real test field in Tuscany. In particular, a traditional hot mix asphalt mixture was chosen as a reference material to study the effect of the crumb rubber’s addition; and three experimental mixtures were produced. One hot mix asphalt with optimized texture and polymer modified binder; and two recycled tire rubber modified asphalt mixtures using the dry and wet process and the warm mix asphalt technology were investigated. The test sections were monitored to check the functional properties by using a laser profilometer to evaluate the macrotexture characteristics, and a Skiddometer to evaluate the friction. The Close Proximity method was used to evaluating the acoustic properties, and specific environmental and biological measurements were performed to evaluate the exposure levels of the workers. The results showed higher macrotexture and friction values for the mixture containing crumb rubber modifier compared to the reference mixtures. Regarding the acoustical measurements, the mixtures containing crumb rubber present better acoustical performances with 1dB(A) breakdown than the reference mixtures. For the environmental measurements, the crumb rubber mixtures present always greater values of PAHs but the overall exposure levels were similar to traditional asphalt mixtures.
