Mechanical and Performance-Related Properties of Asphalt Mixes Containing Expanded Clay Aggregate

The use of artificial aggregates such as expanded clay in the production of asphalt concrete makes it possible to reduce both natural aggregate extraction and the use of nonrenewable raw resources, greatly benefiting the environment. Moreover, the expanded clay production process allows nondangerous waste materials to be reclaimed and thereby avoids the necessity to dispose of them in a landfill or dump–this benefits the environment and also offers economic advantages. This paper reports on the results of laboratory and in situ tests to evaluate the feasibility and advantages of using expanded clay in producing asphalt mixes for use in urban areas to reduce traffic noise. Some experimental low-noise asphalt surfaces were laid, with 15% of expanded clay by weight, and mechanical as well as performance properties were then evaluated. The mechanical characteristics, friction, and acoustic performance, in contrast to results with traditional asphalt surfaces, demonstrated the considerable benefits of using expanded clay in asphalt mixes for surface layers. In particular, the results of friction increase and noise-spectrum reduction are of interest.