A "common programme for the 21^st century" adopted by 178 countries at the Rio Conference in 1992. It lists a series of actions to be incorporated into national legislation as a priority in order to move towards sustainable development (social equity, economic efficiency, ecological viability). Many local authorities have now incorporated Agenda 21 into their policies.

In roadbuilding, aggregate is the generic name for pebbles smaller than 80 mm in size. Aggregate is bound with bitumen to form an asphalt mix.

In roadbuilding, asphalt mix is the material used to cover the road pavement (the part of the road on which vehicles travel). It is made of aggregate (sand and gravel) bound with bitumen and applied in one or more layers. It is made and laid hot (at around 160°C) so that it remains malleable for placement despite its high viscosity.

This Colas innovation produces asphalt mix at lower temperatures than conventional mixes to make a 10 to 20% energy saving and emit less CO₂. 3E^® asphalt mixes (Environment-friendly, Energy-Efficient) are manufactured at temperatures as much as 40°C lower than conventional mixes. So how are they made just as malleable with less heat? They are produced in two ways: by incorporating additives (based on surfactants) or by double coating to reduce their viscosity. By using less fuel for heating, they save energy and emit less greenhouse gas. Paving one kilometre of road with 3E^® asphalt mix therefore saves the energy equivalent of three days' output from an industrial wind turbine. As the temperature is lower, it also improves working conditions for roadbuilders. The other characteristics of 3E^® asphalt mix are similar to those of conventional asphalts. In fact 3E^® asphalt mix is even more durable: because it is heated to a lower temperature, it changes less after manufacture. 3E^® asphalt mix has been tested in France since 2004, and in 2007 received an innovation award from the Roads Department of the Ministry of Ecology, Energy, Sustainable Development and Regional Development. In 2008, 3E asphalt mix was developed to include 25% recycled materials, still with the same manufacturing temperature. Low-temperature 3E^® asphalt mixes as a proportion of Colas' global production of asphalt mixes rose from 2% in 2009 to 6% in 2010.Colas is targeting 10% for 2011.