Crushed concrete in road structures – two decades of experience

Since the early 1990s, crushed concrete aggregate (CCA)/recycled concrete aggregate has been successfully used in Finnish road constructions. The aim of this paper is to analyse the long-term behaviour of CCA and to compare CCA with conventional mineral aggregates in road structures. The analysed trial sections consist of the road and highway pavements where CCA has been used in the base and subbase layers. The first studied Finnish trial section was constructed in 1995, which has enabled nearly two decades of follow-up studies. In total, five follow-up trial sections were studied. E-modulus of pavement layers was determined using the deflection data from falling weight deflectometer measurements. The studies revealed excellent long-term behaviour in the CCA build pavements and validated the suitability of chosen design parameters in previous guidelines. In this study, the sections consisting of maximum 50 mm particles of CCA in the base or subbase layer gained 10–25% larger bearing capacity in 13–15 years after construction than the reference pavements that were constructed with crushed rock. The increase of the CCA stiffness was faster in the first years after construction and in the 2–5 years little or insignificant increase in such stiffness could be observed.