Recycled concrete aggregates (RCA) are used in new concrete mixes, termed recycled aggregate concrete
(RAC). Among losses in most fresh and hardened properties, literature reports that RAC suffers increased
levels of drying shrinkage compared to equivalent mixes incorporating conventional aggregates. This paper
describes the procedure and results of a range of experiments conducted on a commercial RCA and its use in
new concrete mixes. In particular, this work quantifies the effect 100% RCA has on the drying shrinkage of the
resulting concrete. A commercially available RCA was characterised by analysing the particle shape and
texture, percentage of solid contaminants, particle size distribution, water absorption and particle densities.
The types of rocks present were analysed through the preparation of thin sections. Three concrete mixes were
prepared and tested for workability, 7 and 28 day compressive strengths and 112 days of drying shrinkage. The
mixes included a 40 MPa control mix incorporating natural crushed aggregates and two equivalent RAC
mixes, one with 30% fly ash as a partial cement replacement and one without. The results indicated that the
commercial RCA has been produced quite efficiently with negligible solid contaminants. However, due to
adhered mortar found on the aggregate particles, the RCA was found to have rougher particle textures,
increased water absorptions and lower densities than conventional crushed aggregates. Due to these
properties and the subsequent increased water demand the RAC mixes suffered lower compressive strengths
and higher drying shrinkages than the control mix. The RAC mix incorporating no fly ash was found to have a
25% average increase in the 112 day drying shrinkage from the control mix while the fly ash mix only had a 7%