Noise pollution coming from traffic noise has become an important issue in urban areas. Road noise is one of the main sources of high-level traffic noise. Road noise depends not only on tires but on the pavement. Therefore, a study of mixture parameters should be performed to achieve good acoustic performance. Another important point which has to be taken into account is the acoustic performance durability. Gap-graded mixtures were selected for this project due to poor experiences with open-graded mixtures in terms of performance durability, where texture and clogging issues appeared a few years after paving. The LIFE SOUNDLESS project is seeking different ways to modify stone mastic asphalt mixes to improve the noise attenuation of pavements. A selection of mixes with different additives were created, where some waste materials were used. The selection of the best mixtures was done not only according to traditional mechanical parameters but also others, such as damping and dynamic stiffness. Once the best mixtures had been paved, the acoustic performances were measured several times to evaluate the performance durability. Several experimental methods like the close proximity (CPX) method and statistical pass by (SPB) method were used to check the sound generation and propagation of every pavement. The project was carried out on two roads overseen by the Junta de Andalucía in Seville (Spain). The difference between both roads was the traffic density and the average speed. The noise level has since been reduced by 3 dB and 7 dB on both sites.
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