Speaker
Description
Abstract. Acoustical durability is an important factor influencing the ser-vice life of low noise semi-dense asphalt (SDA) pavements in Switzerland. The main factors affecting this property are the reduction in porosity from traffic loadi and especially clogging of pores during the service life. Over the past decade, an extensive database on the in-situ acoustical performance of SDA mixtures in Switzerland has been compiled. The reduction of pave-ment noise relative to dense asphalt measured by the Close-Proximity (CPX) method at various stages in the SDA service life has brought consid-erable benefits to the population living along traffic corridors in terms of noise reduction. However, many SDA sections have underperformed acous-tically. This underperformance has to do with low target voids of the mix-ture designs and the susceptibility of porous SDA to clogging over time. The purpose of the current work is to employ the long-term SDA perfor-mance data to design more acoustically durable SDA mixtures. By inputting in-situ acoustical data collected over the pavement life, the key mix design parameters for good acoustical durability in SDA are derived. It was found that a void content of 15 ± 1% as well as limiting the filler and fines con-tents were consistent with improved long-term acoustical performance. These optimized mixture designs were produced in the lab to evaluate if they fulfill the requirements in terms of Marshall void content and water sensitivity. This study aims to improve on the current Swiss standards for SDA, by refining the mix design method with findings from in-situ data and thereby achieving more acoustically durable mix designs.
