Solidification of APC residues using PFA

A pulverised fuel ash (pfa) classed as a waste due to high loss on ignition (LoI) was blended with waste alkali and used to solidify air pollution control (APC) residue from a waste incinerator. The resultant samples were tested for compressive strength and characterised using thermogravimmetric analysis (TGA). The effects of various variables including; l/s ratio, APC content, curing temperature and alkalinity of the liquid phase were examined. Results showed that a lower l/s gave higher compressive strength, analogous to that seen for cement mixes. Curing at slightly elevated temperatures were necessary for setting of the mixes within 7 days. An alkaline liquid fraction increased early age strength. The %(w/w) APC content showed no clear correlation with compressive strength results, but some APC was necessary for the mix to set. Resulys suggest the optimum APC content for compressive strength and solidification may be between 10-20%.