Reuse of waste sludge from papermaking process in cement composites

Papermaking sludge (PS), a waste residue from the pulp and paper processing, has brought great pressure on the environment because of large quantities that are produced in paper mills. This work was carried out to explore the possibility of making PS/cement composite products using solid waste of PS. Boards measuring 350 x 270 x 12 mm3 were manufactured using PS contents of 40, 50, and 60 wt%, adhesive dosages of 0, 10, and 15 wt%, and 0 and 5 wt% of calcium chloride as an accelerator. At least three replications were fabricated for each treatment, and some mechanical and physical properties of the boards were evaluated. Test results showed that the bending and internal strengths of the specimens decreased with an increase in the PS content, and the maximum values were obtained at PS loading of 40 wt%. The negative influence of PS content on the mechanical properties can be explained by the reduced bonding ability because of weaker PS compared with cement. Screw withdrawal values were up to 22.7 kPa. Water absorption and thickness swelling of cement mortar considerably increased with increased content of PS, with a corresponding reduction of bulk density. In general, all properties of the boards were improved when the adhesive and calcium chloride contents were increased. The results showed that an increase in board density improved the mechanical and physical properties. Finally, results showed that PS has good potential for recycling and utilization in developing value-added building components. POLYM. ENG. SCI., 2013. (c) 2012 Society of Plastics Engineers