Viability of the use of construction and demolition waste aggregates in alkali-activated mortars

This study explores the technological feasibility of using construction and demolition waste (C&DW) as recycled aggregate in alkali activated mortars, ascertaining the mechanical and microstructural behavior. Shrinkage behavior of alkali activated slag mortars (AAS) and fire resistance of alkali activated fly ash (AAFA) incorporating recycled aggregates have been also tested Normalized siliceous sand and two types of recycled concrete aggregates were used in the mixes at different proportions. The findings showed that water demand was higher in mortars prepared with recycled aggregate. Partial replacement (20% - 80/20) of conventional aggregate with the recycled material was also observed to yield mortars with high mechanical strength, although total porosity also rose. Total replaclement, gave worse mechanical performance however. Fire resistance and shrinkage studies conducted indicated that alkaline cement mortars prepared with 80/20 recycled aggregated exhibit acceptable performance.