Ceramic waste as aggregate and supplementary cementing material: A combined action to contrast alkali silica reaction (ASR)

Recently, many efforts have been made to recycle waste of different nature as constituents of sustainable concrete. This practice produces large environmental benefits that can be further extended if deleterious chemical side-reactions, deriving from the use of some types of waste and/or raw materials, could be prevented and suppressed. This paper presents the combined action of different ceramic wastes partially replacing natural sand and cement, respectively. Alkali silica reaction (ASR) promoted by boron–silicate and lead–silicate glass used as fine aggregates (64 mm) is limited and controlled by using a new type of blended cement based on a siliceous residue coming from sludge produced by the polishing of porcelain stoneware tiles. The results of expansion tests carried out in accelerated conditions together with mechanical and microstructure characterisations of mortar samples highlight the combined action of the investigated wastes. Indeed, the blended cement containing porcelain stoneware polishing residue can be effectively exploited as valid alternative to pozzolan cement.