Investigation on material properties and surface characteristics related to tyre–road noise for thin layer surfacings

• The research focuses on the properties of thin layer road surfacings.
• Surface characteristics related to tyre–road noise are measured and observed.
• Influences of material properties on texture and sound absorption are analyzed.
• Relationship between connected air voids contend and overall porosity is studied.
• Free field technology is introduced to test the sound absorption of road samples.

Thin layer surfacings are very popular to reduce tyre–road noise in the Netherlands and some other European countries. In this study, laboratory measurements were carried out to investigate the mixture composition, surface texture and sound absorption of thin layer surfacings. Both slab samples produced in the lab and the cores drilled from trial sections were used for measurements. Observations were made on the test results, and the influence of different material properties on the texture and sound absorption were investigated. A relationship between the connected air voids content and the overall porosity of the surface is also analyzed.