Evaluating physical-mechanical properties and long periods environmental risk of fired clay bricks incorporated with electroplating sludge

Electroplating sludge (ES) is regularly listed as the hazardous waste in all the world, and its treatment is always a pressing problem for environment safety. This study introduced this sludge into the production of fired clay bricks in lab scale, not only consumed a large amount of this sludge but also provided an available raw material for building materials industries. Two types clay, brown clay and red clay, were mixed with ES and used in the production of bricks. Physical property tests showed that the introduction of ES with mass fraction of 10 wt% impacted slightly mass loss, linear shrinkage and bulk density. However, water absorption increased by 15% and compressive strength declined more than 30%. Porosity analysis showed that the introduction of ES enhanced porosity and enlarged pore volume and size. These negative impacts bought by the incorporation of ES can be remedied by elevating firing temperature. Long periods leaching tests for 10 days proved that the releasing concentrations of all heavy metals (Cu, Zn, Cr and Ni) from fired samples containing 10 wt% of ES were under 1 mg/L, far below the corresponding regulation limitation values. This study indicated that ES could be sustainably used in the manufacturing process of fired bricks or ceramics, and the influences on physical-mechanical properties bought by the introduction of ES could be remedied by elevating firing temperature or others ways.