Use of Secondary Slags in Completely Recyclable Concrete

Abstract

A completely recyclable concrete (CRC) is designed to have a chemical composition equivalent to the one of general raw materials for cement production. By doing so, this CRC can be used at the end of its service life in the cement clinkering process without need for ingredient adjustments, and with improvement of the resource efficiency of cement and concrete production. Copper slag is interesting as an iron source for the production of such a CRC and can be added to concrete, either as alternative binder or as aggregate. By isothermal calorimetry and compressive strength tests it was found that the addition of copper slag as cement replacement is of minor interest. But a study toward the compressive strength and durability of concrete with copper slag as aggregate replacement had promising results. The performance of these concretes was comparable with or even better than the reference concrete, regarding strength and most durability aspects such as porosity and permeability, and resistance against carbonation and chloride ingress. Only the resistance to freeze-thaw attack with deicing agents was inferior.