Innovation Sostenibilidad

New European patent to reduce pollution from asphalt pavements

Patente europea para reducir la contaminación de los pavimentos asfálticos

Sacyr Construcción, in collaboration with other companies, has been awarded a European patent from the European Patent Office, reference number 14280020, entitled Surface treatment of asphalt road pavements with photocatalytic composition for the abatement of atmospheric pollutants”.

Photocatalysis is a natural phenomenon in which a substance known as a photocatalyst (TiO2) changes the speed of a chemical reaction through the action of light (whether natural or artificial). In the presence of humidity, air and light, an intense process of oxidation becomes activated which leads to the decomposition of the organic pollutants that come into contact with these surfaces.

The polluting and toxic substances transform through photocatalysis into sodium nitrate (NaNO3), sodium carbonates (Na2CO3) and calcium carbonate (CaCO3), which are harmless and measurable in ppb. The result is a considerable reduction in the toxic pollutants produced by vehicles, factories, household heating and other sources.

What is the patent like?

Atmospheric pollution in large cities is a global issue that is being tackled on many different fronts: improvements to vehicles, promoting public transport, restrictions on use of private vehicles in city centres, cleaner fuels, etc. In addition, over the last decade great advances have been made in technologies capable of eliminating some of the most hazardous chemical compounds that give rise to air pollution. These technologies include the use of materials with photocatalytic capabilities, that enable the elimination of nitrogen oxides, ozone and volatile organic compounds.

This invention consists of a photocatalytic treatment that has been specially designed to be applied to asphalt road pavements. The photocatalytic particles can be applied using any pulverisation system.

The dispersal of the photocatalytic substance must be formulated so that it enables the particles not to clump together, to be stable in storage and to be very fluid to adequately cover the holes in the pavement, and provides a sufficient level of adherence between the particles of the photocatalytic substance and the aggregates and bituminous mastics that make up the asphalt road pavements.

The invention is applicable both to new asphalt floor surfaces and to those already in service, although the latter need first to be cleaned using high-pressure water to remove any remnants of dirt that might impede the adherence of the photocatalytic particles to the aggregates and bituminous mastics.

Summary of invention innovations

The project for this patent has been jointly developed by several companies working in collaboration with each other, namely Sacyr Contrucción, Serviá Cantó (the FCC Group), Repsol, Fundación Cartif and Asfaltos y Construcciones Elsan (the OHL Group), and includes a series of innovations such as:

  • High levels of anti-pollutant power through the use of very limited percentages of the photocatalyst and resin. The resin is used to ensure the photocatalytic particles stick properly to the asphalt road pavement.
  • Using large amounts of resin is negative as it covers the photocatalytic particles thus removing their photocatalytic ability through not allowing contact with the polluting gases.
  • Stability while stored.
  • Definition of the pairing of the photocatalytic solution and the type of paving surface to ensure the durability of the treatment through reducing the abrasive effect of tyres. An ideal macrotexture level can be defined.

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