Limiting properties in the characterisation of mixed recycled aggregates for use in the manufacture of concrete

Recycling of construction and demolition waste (CDW) has become a widespread concern in Spain for the last years, as a way to preserve natural resources and achieve a better control of waste disposal sites. Specific applications which make use of mixed recycled aggregates are of great importance, as this types of aggregates constitute the majority of the total production. Structural and non-structural concrete is one of the possible applications, being this the main goal of our study.This paper presents a study on the physical and chemical characteristics of mixed recycled aggregates which have been obtained from different CDW treatment plants of Spain. Correlations between the different properties were investigated in order to find criterions of acceptance for recycled aggregates to be used in concrete.The comparison between the properties offers the possibility of pre-selecting a great quantity of mixed recycled aggregates, these being suitable for either structural and non-structural concrete. The determination of water absorption and the gypsum content are good indicators in order to evaluate the quality of the mixed recycled aggregates for its application in the production of concrete.

► In this research study 35 recycled aggregates, proceding from 11 processing plants C&DW, were analysed.
► We propose a new classification of different recycled aggregates based on their composition.
► We have obtained mean values and extremes of density and water absorption in 24 h of the three groups of materials (concrete, mixed and ceramic).
► Finally, we propose a rapid method of acceptance or rejection of recycled aggregates based on two tests, composition and absorption at 10 min.