An investigation into the strength development of wastepaper sludge ash blended with ground granulated blastfurnace slag

Wastepaper Sludge Ash (WSA) contains reactive components such as free lime (CaO), and less reactive and inert mineral species. When water is added to WSA some constituents hydrate faster than others, lime being the fastest giving high alkalinity to the solution. If the WSA is combined with Ground Granulated Blastfurnace Slag (GGBS) then the latter, activated by the raised pH, produces new minerals which will contribute further to the strength development of the paste. The kinetics of the hydration reactions and the possible ways of making lime a more effective contributor in activating other phases in the WSA-GGBS system are discussed.