Cement substitution by a recycled cement paste fine: Role of the residual anhydrous clinker

This paper reports on an experimental study conducted on mortars designed with substitution of Portland cement by a recycled cement paste fine (RCPF) obtained from crushing, grinding and 80-μm sieving of a laboratory-made cement paste. The obtained results show that in terms of fineness, particle size distribution, CaCO3 content, hydration kinetics, total porosity and mechanical properties, the use of RCPF as partial substitution of cement should not provide any additional filler effect and nucleation sites compared to the replaced cement. The results show also that RCPF contains around 24% of a reactive residual anhydrous clinker which contributes in the hydration process, the mechanical properties and the resistance against carbonation.