Influence of activated drinking-water treatment waste on binary cement-based composite behavior: Characterization and properties

Drinking water treatment plants regularly dispose of large volumes of industrial sludge in landfill sites, which often has negative environmental consequences. The calcination products of these kaolinite-based sludges have properties that could make them appropriate supplementary cementing materials in the production of blended binary cements.This research analyses the pozzolanic and thermodynamic properties of a Venezuelan drinking water sludge activated at 600 °C for 2 h and its behavior in blended cement matrices prepared with 15% Activated Waste (AW) and 85% Ordinary Portland Cement (OPC). Our results show that this activated drinking water sludge presents high pozzolanic properties, mainly during the first 24 h of reaction. The XRD, SEM/EDX and thermodynamic studies confirm the formation of C2ASH8, C–S–H gels and C4AH13 as the hydration products from the pozzolanic reaction. The binary mixture of 15% AW/85% OPC complied with the physical and mechanical specifications contained in current European cement standards.