This Digest provides guidance to engineers and builders on selecting and placing material for use as hardcore in building construction. It takes account of recent standards for specifying aggregate materials for use as hardcore, ensuring that the material is both physically stable and chemically inert.

In Part 1 candidate materials are reviewed, including recycled and secondary materials that are currently being promoted for use in construction as a sustainable option. Simplified recommendations for common situations are also given.

Part 2 deals with placing and compacting hardcore material. It also reviews some unsuitable materials that were used for hardcore before the mid-1970s, both as a cautionary note for current specifiers and as a guide for professionals dealing with a legacy of unstable hardcore problems in existing buildings.