Potentiality for using paper sludge waste in the manufacture of red wall tiles

Paper sludge waste is produced on a large scale by the paper industry and causes high environmental impacts. This work investigates the potential of paper sludge waste incorporation as an alternative raw material into a red wall tile formulation, replacing traditional limestone material by up to 5 wt%. Red wall tile pieces containing paper sludge waste were produced by uniaxial dry pressing and fired at 1170 °C using a fast-firing cycle. Technical properties of the fired wall tile pieces have been determined. The development of the fired microstructure was determined by scanning electron microscopy (SEM). It was found a water absorption of 17.15 to 18.31 %, a lexural strength of 15.77 to 16.17 MPa, a linear shrinkage of 2.88 to 3.22 %, and an apparent density of 1.76 to 1.81 g/cm3. Therefore, the results indicated that the paper sludge waste, in the range of up to 5 wt%, can produce red wall tiles (group-BIII in the ISO 13006). At the same time, this application helps minimize the environmental impacts caused by the paper industry.