Expected potential of bound and recycled backfill material in low temperature district heating networks

Abstract

Special requirements for backfill material for district heating pipes are defined in the relevant standards and codes of practice. Sands shall be used in particular in the pipe zone around the pipe perimeter. Significant costs for adequate bedding material are reported unless sands are available in the local region. Because of this, the economic optimization of utilities has led to construction projects where the trench spoil is reused for the whole trench. Furthermore, the reuse of materials within the construction industry is a key element in achieving sustainable construction, with targets related to sustainability becoming an increasingly important part of tendering. Bound and recycled materials for backfilling are modern options for fulfilling these targets. Decreasing supply temperatures in future networks may mean that static design issues become a background concern. Mechanical soil issues preventing the application of bound and recycled materials will then only play a minor role. This makes new economic and environmental friendly backfilling possible.