Shear behaviour and environmental impact of single and multi-generation recycled aggregate concrete beams

Recycled aggregate concrete (RAC) is often presented as a solution to both the significant consumption of natural aggregates by the concrete sector and the significant landfill contribution of the construction sector. To extend the concept of recycled aggregate to a circular economy it is necessary to consider how RAC can be reused and this has led to the concept of multi-generation RAC (MGRAC). To date the investigation of MGRAC has largely been restricted to the material level. In this work we extend to the member level by considering, for the first time, the shear capacity of MGRAC beams using virgin aggregate concrete and three generations of recycled aggregate concrete at an equivalent compressive strength. The results of this experimental work show that there is no clear difference in the shear capacity of single or multi- generation RAC. The MGRAC results generated in this work are then brought together with the results of RAC shear tests highlighting the limitations in existing models and identifying suitable approaches for predicting shear capacity. A simple life-cycle assessment is performed to quantify the impact of using RAC and MGRAC on global warming and natural resource consumption when using a functional unit that allows for changes in member performance. The outcome of this work shows the potential benefit of MGRAC in terms of saving natural resources. • The shear performance of multi-generation recycled aggregate concrete beams was determined. • The experimental work shows that there is no clear difference in the shear capacity of single or multi-generation RAC. • Suitable approaches for predicting shear capacity were identified. • The impact of using RAC or MGRAC on global warming and natural resource consumption was quantified. • The outcome of this work shows the potential benefit of MGRAC in terms of saving natural resources.