Background Modern paved roads are an essential part of a country’s infrastructure and the European road network is estimated at over 5.5 million km. However, each kilometre of road covers what was once natural land and consumes a large amount of materials and energy in its construction and maintenance. The OECD has reported that typically 10 000 m3 of aggregates are needed for each kilometre of two-lane road constructed. Bitumen used in road construction is derived from fossil fuels, and asphalt manufacturing produces a number of air pollutants. These include particulate matter (PM), nitrogen oxides (NOx), sulphur oxides (SOx), carbon monoxide (CO), volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAH) and carbon dioxide (CO2). It is estimated that each tonne of hot mixed asphalt produces 34.97 kg of equivalent CO2. There is potential for making major environmental improvement through the development and implementation of more eco-friendly practices in the road-building sector. At present, policies targeting encouragement of Green Public Procurement (GPP) have yet to make the desired impact in the industry. Objectives The 'GREENROAD' project aims to provide achievable ways for the road sector to become greener and to set an example of sustainable programmes of public works. It specifically aims to demonstrate the technical and economic viability of using at least 90% recycled asphalt mixtures in road construction. At the same time, it expects to revalorise industrial waste from the region that otherwise entails high environmental and economic costs. The project will work to produce an optimal composition of asphalt using eco-mixtures composed of steel slag, wastes from pilot road milling and end-of-life tyres. It hopes to minimise the amount of natural resources used as raw material, reduce the required temperatures of the production process and minimise energy consumption. It will seek to validate the high technical performance of these asphalt mixtures in “real” environments. It will also demonstrate the environmental and economic benefits of using recycled waste products in asphalt production. Lifecycle analysis will be carried out, including data on carbon footprints and resource consumption comparing 'GREENROAD' eco-mixtures with conventional ones. This ultimately seeks to significantly improve implementation of GPP in construction contracts and enable municipal and other public works construction contracts to include a requirement for use of green asphalts. It will seek to establish the requirements needed to implement successfully a GPP Action Plan for use in road construction generally. It will also undertake in-depth analysis of the potential for the replication of the mixtures in other environments outside the project area. Expected results Production of high performance asphalt comprising less than 10% natural resources; Valorisation of 800 tonnes of black slag from steel mills in Cantabria, 80 tonnes of milling wastes, and 2 tonnes of rubber from old tyres; Reduction in consumption of natural aggregates by 880 tonnes; A 20 ºC reduction in production temperatures; A 20% reduction in manufacturing energy consumption; A 30% reduction in emissions of greenhouse gases at the production site – from revalorisation of wastes and improvement in energy efficiency; A 20% reduction in the price of asphalt mixtures; Establishment of a GPP procurement criteria for use with the award of road construction contracts; and Encouragement of new and wider markets for steel slag and reclaimed road materials.