Chloride ion ingress and chloride-induced corrosion initiation of coarse CCA structural concrete

The specification of crushed concrete aggregates (CCA) is increasing, with the construction industry still seeking new ways to improve the quality and performance. In higher value applications, such as structural concrete, further research is required to understand the effect of coarse CCAs, particularly on durability. This 4 year research programme investigated the effect of coarse CCA on transport mechanisms within CEM I and CEM III/A structural concretes, with particular emphasis on chloride ion ingress and corrosion initiation. CEM III/A concretes with up to 100% coarse CCA outperformed control CEM I concrete with 100% natural aggregates in durability performance tests, irrespective of the source of CCA. The results indicate that coarse CCA can be incorporated up to 60% replacement of natural aggregates if the criterion for compressive strength compliance at 28 days is relaxed for CEM III/A concretes. Water absorption, chemical and petrographic analysis, of the sources of coarse CCA with known compositions, had a good correlation with durability performance. This type of testing is recommended on future construction projects to mitigate potential risks.