The influence of thermal activation of art paper sludge on the technical properties of blended Portland cements

The influence of the thermal activation (600–750 °C) of a clayey waste (art paper sludge, APS) and the replacement rate of cement by this pozzolan on technical parameters such as normal consistency water, setting time, soundness and compressive strength were investigated. Physical properties of raw materials such as particle size distribution and BET surface areas were also reported. The results have demonstrated that substitution of Portland cement CEM I 42.5 by activated art paper sludge (AAPS) increases normal consistency water and decreases the setting times and compressive strength of the blended cements, with increasing replacement rate, temperature and/or time of activation. However, if APS is properly activated at around 600–650 °C for 2 h, it is feasible to substitute a 10% of cement without adverse effects on technical properties, due to the pozzolanic activity of metakaolinite and set regulator features of calcite, the two major mineral phases present in AAPS.