Preliminary investigation of the effect of air-pollution-control residue from waste incineration on the properties of cement paste and mortar

For preliminary assessment of the engineering properties of concrete with air-pollution-control residue from waste incineration (APC) the possible reactivity of APC and the effect of APC on cement hydration were investigated by isothermal calorimetry, chemical shrinkage (pychnometry), thermal analysis (TG), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Furthermore, compressive strength development was measured and impregnated plane sections were prepared. The APC was from a Danish wet process plant. Although the APC contained high amounts of chloride (approx. 10%) and heavy metals (approx. 3%) the preliminary studies were performed on untreated samples to evaluate the possible application of the least expensive materials and processes. Pastes and mortars of low alkali sulphate resistant Portland cement with 0%, 10%, and 20% APC substitution were prepared. Mixes with 10% and 20% APC showed a major retarding effect of APC on the development of hydration. The APC was found to be pozzolanic. Chemical shrinkage measurements indicated early expansive reactions of pastes with the APC including evolution of air. Crack formation was observed in mortars with APC, and strength loss at 96 days was observed in samples with 20% APC. Alkali silica reactions (ASR) were observed in 28 days old mortars with APC; however, it is still to be confirmed to which extent ASR was a primary cause of damage.