On the possibility of using recycled mixed aggregates and GICC thermal plant wastes in non-structural concrete elements

Abstract

Industrial wastes are often used as aggregate in concrete production to promote a more sustainable construction and to reduce production costs. This article presents the results of an experimental campaign on the influence of replacing natural aggregate with several construction and demolition wastes (C & DW) as recycled aggregate, as well as the use of fly ash and slag, wastes produced in Gas Incinerator Combined Cycle (GICC) thermal power plants, in the mix design of non-structural concrete. Different percentages of natural aggregates were substituted with recycled aggregates either coming from construction and demolition wastes, or from the coarse fraction of the slags from thermic plants in the manufacture of concrete. The mechanical properties, capillary water absorption, density, carbonation, chloride ingress and sulphate resistance have been tested. The results show a decrease in properties when C & DW are used. Fine fraction of slag and fly ash has an important advantage, and can even improve the long term properties of concrete prepared with natural aggregates. Coarse fraction of slag as a recycled aggregate generally improves most of the properties of manufactured concretes.