Mechanical and Durability Assessment of Concretes Obtained from Recycled Ultra-High Performance Concretes

The aim of this work is to analyse the mechanical and durability properties of Recycled Ultra High Performance Concretes (RUHPC) containing different amounts of recycled fine aggregate obtained from crushing Ultra High Performance Concretes (UHPC). This paper summarizes and compares the results from different experimental campaigns carried out in the framework of the ReSHEALience project (Rethinking coastal defence and Green-energy service infrastructures through enhanced-durAbiLity high-performance cement-based materials) which has received funding from the European Union’s Horizon 2020 programme (GA 760824). Mechanical performance was evaluated by means of compressive and flexural tests, whereas durability was evaluated by means of chloride penetration, chloride migration and water absorption capillary tests. The results indicated that replacing 50% or 100% of natural aggregates with recycled aggregates did not significantly affect neither compressive strength nor flexural strength. In the case of high replacement rates, a slight decrease in workability was detected, but the mix retained its self-compacting properties. RUHPC had similar durability performance as UHPC. In conclusion, the results have shown that it is feasible to produce RUHPC; the recycled fine aggregate has shown great potential to be used in the production of new UHPC. Scalability of the recycling procedure to industrial level was also addressed in order to pave the way towards the uptake from the different value chain actors of the construction industry of the innovation potential demonstrated by the research.