Large amounts of sludge are produced in China every year. Non-hazardous treatment and recycling technology is vital for industrial production to deal with sludge pollution problems

in which sludge solidification technology is of great importance. The hygroscopic and self-hardening properties of paper sludge ash are the beneficial to produce cost-effective sludge curing agent formulation. It is a worthwhile and environmental friendly to make use of wastes induced by paper production industries. The basic engineering properties of paper sludge ash have been studied in this study first. Furthermore sludge solidification tests have been carried out

including pH value

heavy metals in the extracting solution

hygroscopic property

microstructure and shear strength

and on the basis

the unconfined compression strength of solidified sludge using paper sludge ash. The results indicate: the paper sludge ash is weakly alkaline

the extracting heavy metals is of little pollution

hygroscopic property decreases with increasing pressure and there is a minimum water absorption; shear strength decreases with the water content increases; paper sludge ash can improve the unconfined compression strength of solidified sludge; and the shear strength increase obviously with higher cement content.