Durability of Concrete with Recycled Aggregate

A demand for a more sustainable use of resources entails that recycled aggregate material need to be used in advanced applications, as in concrete. Even if regulations and standards permit the use of recycled aggregate in concrete, the amount used for this application in many countries is negligible. This caution of the potential users is partly due to the uncertainty about how recycled aggregate, from construction and demolition waste and from washed excavation masses, influence the durability of concrete, such as alkali-silica resistance (ASR), frost resistance and carbonation. Choosing a binder that mitigate damaging alkali silica reactions is an effective means to diminish the risk for damage, even with alkali-reactive recycled aggregate. However, the alkali content of crushed concrete used as aggregate must be considered. No negative effect of recycled aggregate on the carbonation of concrete was observed. The uncertainty about the influence of aggregate porosity on the frost resistance of concrete, about adequate concrete test methods, about aggregate test criteria, and about the correlation between aggregate and concrete test methods need to be settled, before porous recycled aggregate like construction and demolition waste (CDW) can be used in more demanding exposure classes with respect to frost.