Total budget: 1.448.377€ €
Demonstration project co-funded by the European Union LIFE SOUNDLESS, whose main objective was to demonstrate the effectiveness and durability of SMA type sound-reducing mixes to mitigate noise pollution at source. the mitigation of noise pollution in urban areas through the design of new sound-reducing asphalt mixes that generate lower noise emission levels and with a durability at least equal to that of conventional AC type mixes.
Furthermore, it focuses on the effectiveness of these mixes in Mediterranean climates (southern Europe), where the climatic conditions are very different from those in northern countries, where they have more experience in the use and performance of porous sound-absorbing mixes. This type of porous mixes in dry and warm climates have not given the expected results due to clogging of voids or problems of aggregate detachment in braking zones and severe tangential stresses. In addition, to emphasise the environmental character of the LIFE-SOUNDLESS mixtures, waste from other industries whose effect on noise reduction has been studied was incorporated into its composition.
After a first stage in which the demonstration sections were studied and selected from an acoustic point of view, in parallel, the design of the sound-reducing bituminous mixes was carried out at laboratory level, incorporating waste from other industrial sectors (rubber powder from NFU, plastic waste, nylon fibres from NFU).
Subsequently, pilot sections were built on two roads in the province of Seville, one on the A-8058 in Puerto Gelves, and the other on the A-376 as it passes through Montequinto.
Between the two sections, a total of 5 different sound-reducing mixtures, previously designed in the laboratory, and a reference mixture were used to compare them. Specifically, the mixtures selected for the full-scale demonstrations were as follows:
Scenario 1: A-8058
• SMA8 sono-reducing mix: 1% rubber over mix (bitumen 6%)
• SMA8 sono-reducing mix: 1.5% rubber over mix (6.5% bitumen)
Scenario 2: A-376
• SMA8 sono-reducing mix: 0.5% nylon
• SMA8 sono-reducing mix: 1% recycled plastic
• SMA8 sono-reducing blend: 0.5% rubber + 0.5% recycled plastic
• Reference mixture: AC16 SURF S
Finally, to evaluate the mechanical and acoustic behaviour of the mixes and their evolution over time, the sections were monitored for a period of two years (CPX, SPB, Acoustic Absorption, Mechanical Impedance, Macrotexture measurements, among others), obtaining satisfactory results from an acoustic point of view:
• – The noise level was reduced by 6 dB on the A-376 road (interurban road with average speed of 70 km/h) and by 3 dB on the A-8058 road (urban road with average speed of 50 km/h).
• – SOUNDLESS mixtures allow to reduce road noise by 3 dB compared to a newly extended reference mixture (AC16 surf) at low speeds (50 km/h) and by 4 dB at medium speeds (80 km/h).
LIFESOUNDLESS LIFE14 Project ENV/ES/000708
With the support of the Financial Instrument LIFE of the European Union.