# Acoustic Performance of Stone Mastic Asphalts with Crumb Rubber and Polymeric Additives in Warm, Dry Climates

## TL;DR

This paper studies how adding crumb rubber and polymers to road asphalt reduces traffic noise in warm, dry climates.

## Contribution

The study provides new design recommendations for low-noise pavements in warm, dry climates using additives like crumb rubber.

## Key findings

- Adding 1% of additives reduces traffic noise by about 1.18 decibels.
- Noise levels in modified asphalt sections did not increase by more than 3 dB over 24 months.
- Design recommendations for macrotexture and voids are proposed for warm, dry climates.

## Abstract

Traffic noise is one of the main sources of environmental problems and a growing challenge for national traffic authorities. It is widely accepted that tire-pavement interaction is the main cause of traffic noise at speeds between 40 and 90 km/h. Typically, noise attenuation strategies include earthworks, tree belts, or noise barriers. However, a solution that is almost always viable is the use of low-noise pavements, which are characterized by their porous macrotexture, such as Stone Mastic Asphalt (SMA) mixtures. These mixtures are increasingly used for heavy traffic volumes because of their many advantages, including drainage properties and mechanical strength. Based on the experimental results obtained on different roads in southern Spain, this paper compares noise reduction in an SMA standard mixture due to the incorporation of different additives, such as crumb rubber and polymeric additives. According to the analysis, increasing the additives content by 1% reduces CPX by 1.18 decibels, approximately, and none of the analyzed sections shows increases greater than 3 dB within 24 months. Additionally, the paper proposes design recommendations regarding macrotexture and the percentage of voids for zones with warm, dry climates, such as Mediterranean Spain.