The need for sustainable construction processes which conserve natural resources is well understood and recognized within the industry, and is often realised through recycling materials into layers below the surface course. However, this ‘downgrades’ the use of expensive and increasingly scarce high polished stone value (psv) aggregates. The incorporation of a proportion of an existing surface course layer into a new surface course system is, therefore, highly desirable because it maintains the ‘high value’ application of the high psv aggregate in a surface course layer. With the reduction in requirement for virgin materials, the inclusion of reclaimed asphalt in the surface course layer may also offer benefits in terms of reduced energy and emissions. This report documents a study on the energy used and relative carbon dioxide emissions associated with the recent resurfacing of the M25 scheme between Junctions 6 to 7, from MP43/2 to 47/3. The objectives of the case study were to gain an understanding of the differences and potential savings in energy and carbon dioxide that could be made by the incorporation of a high reclaimed asphalt content (40 %) into the surfacing compared with a 100 % virgin aggregate mixture. The activities undertaken during the resurfacing works were, therefore, audited and compared with a hypothetical scenario where the conventional material would have been laid.

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