Manufactured aggregate from waste materials

The move from natural to synthetic aggregates for use in construction is driven both by mounting legislation and taxation intended to reduce the growing demand for natural aggregates. Despite increasing re-use of crushed concrete from demolition waste, this source alone cannot satisfy the demand for aggregate materials. This paper reports work using cement-bound mineral processing fines, which have been processed to form a synthetic aggregate material. High-shear processing has been used (in combination with polymer additives) to optimise the highest strength with the lowest practical water content, allowing aggregates to be produced by extrusion and kibbling. Using polyvinyl alcohol at loadings up to 3% by mass, produces aggregates with a compressive strength around 25 MPa comparable to many commercial concrete products which use limestone aggregates.