Laboratory, field and environmental characterisation of construction and demolition waste stabilised with pozzolanic cement

Construction and demolition waste aggregates (CDWA) are increasingly used in subbase pavement layers, especially when stabilised with cement to meet strength and stiffness requirements. While cement significantly improves the mechanical properties of CDWA, it also has a relevant environmental impact that offsets the benefits of using them. This field and laboratory investigation, coupled with a life-cycle assessment, evaluates the use of a pozzolanic cement (CEM-IV/B) as an alternative to the conventional Portland-limestone cement (CEM-II/B) for CDWA stabilisation. Two sections of an experimental road, each measuring 40 m in length, were built with a 30 cm cement-stabilised CDWA subbase, with each section using a different cement type. Lightweight deflectometer field tests were performed 3 days after construction. Samples cured for 7 and 28 days were also tested in the laboratory to measure their compressive strength and resilient modulus values. Field measurements showed statistically equivalent surface moduli between the two cement-stabilised materials. The laboratory test results confirmed that the two mixtures had comparable strength and stiffness values. Life cycle analysis revealed that using CEM-IV/B instead of CEM-II/B for CDWA stabilisation resulted in a 16% reduction in its climate change impact. The two cements demonstrated their ability to stabilise CDWA with equivalent bearing capacity in both short- and long-term laboratory and field tests. In light of current European green public procurement policy, preference should be given to CEM-IV/B as a stabiliser for CDWA.