Influence of the quality of recycled aggregates on the mechanical and durability properties of High Performance Concrete

Abstract

The main objective of this experimental work is to analyse the effect of recycled aggregates (RA) on the basis of the study of the various qualities of the physical, mechanical and durability properties of High Performance Concrete (HPC). Three coarse RA sourced from parent concretes of 100, 60 and 40 MPa, one coarse mixed recycled aggregate and one fine ceramic waste aggregate were used as replacement for natural aggregates. On the basis of the findings of our research it was determined that the quality reduction and the increase of RA amount produced a drop with respect to the properties of HPC. According to our analysis of the mechanical properties, a 100% replacement of coarse natural aggregates by recycled concrete aggregates can be employed prodiding the RA has been sourced from a 60MPa minimum-strength concrete. Nevertheless, durability behaviour was greatly influenced by the use of RA, and consequently replacement ratios of high quality RA should be reduced to 50% to achieve similar behaviour patterns to those of natural aggregate concrete. Moreover, severe reductions of RA qualities (sourced from 40MPa strength concretes or mixed waste) only permitted 20% replacement ratios on HPC production. However, those concretes containing fine ceramic RA (up to 30%) reached higher compressive strength, higher chloride-ion penetration resistance and higher improvements of durability properties at longer ages than those concretes produced using natural aggregate concrete.