Use of co-combustion bottom ash to design an acoustic absorbing material for highway noise barriers

•The particle size of bottom ash influenced the acoustic behavior of the barrier.•The best sound absorption coefficients were measured for larger particle sizes.•The maximum noise absorption is displaced to lower frequencies for higher thickness.•A noise barrier was designed with better properties than commercial products.•Recycling products from bottom ash no present leaching and radioactivity problems.

The present study aims to determine and evaluate the applicability of a new product consisting of coal bottom ash mixed with Portland cement in the application of highway noise barriers. In order to effectively recycle the bottom ash, the influence of the grain particle size of bottom ash, the thickness of the panel and the combination of different layers with various particle sizes have been studied, as well as some environmental properties including leachability (EN-12457-4, NEN-7345) and radioactivity tests. Based on the obtained results, the acoustic properties of the final composite material were similar or even better than those found in porous concrete used for the same application. According to this study, the material produced presented no environmental risk.