Cement replacement: Experimental results for concrete with recycled aggregates and fly-ash

Abstract

The experimental activity reported in this chapter was aimed at enhancing the knowledge about the mechanical behaviour and durability of concretes made with Recycled Concrete Aggregates (RCAs) and coal Fly Ash (FA) and their possible use for structural purposes. To this end, starting from a reference concrete composition, twelve mixtures were designed by replacing part of the ordinary constituents (i.e. cement, sand and coarse aggregates) with the FA and RCAs. The time evolution of the compressive strength, as well as the splitting strength, were measured with the aim to monitor the mechanical performance, whereas the durability performance was scrutinised by measuring water permeability, carbonation depth and chloride-ions ingress. The obtained results unveil the influence of both RCAs and FA on the resulting concrete performance and highlight that their combined use can lead to a synergistic effect in terms of the relevant physical and mechanical properties of structural concrete.