ABSTRACT
Research results and practical experience have shown that given the correct grading and other properties, crushed concrete can be successfully used for the production of both cement bound materials and lean concrete. The current UK specifications for cement bound materials includes four categories of material with minimum strength at 7 days ranging from 4MPa to 15 MPa. Of these materials only CBM1 and CBM2 can be manufactured with recycled aggregates since the specifications for CBM3, CBM4, and all categories of wet lean concrete require the aggregate to be either a naturally occurring material complying with BS 882 (1983) or crushed air-cooled blast furnace slag complying with BS 1047 (1983). This represents a change from previous editions of the specifications which required aggregates for cement bound materials to be a washed or processed granular material. This included the use of recycled materials. It is not known what has prompted this change.
