The production of sewage sludge originating from municipal wastewater treatment plants has been increased significantly. Sludge is considered the largest byproduct of wastewater in volume, whose process and disposal is considered one of the most complex environmental problems. This paper reports experimental findings regarding the feasibility of using sewage sludge in concrete as an alternative to freshwater varying from 0 to 100% by weight. The concrete samples were studied with regard to compressive strength and workability. The results showed that sludge can be replaced up to 50% by weight of water without any significant deterioration of mechanical properties. To reinforce concrete strength, rock dust was added to concrete as an alternative to the whole fine aggregates. According to the findings, the presence of rock dust has beneficial effects on compressive strength, whose samples with 50% sludge were comparatively better in terms of compressive strength than the normal concretes. Furthermore, the impact of rock dust on concrete workability was negligible. In addition to environmental conservation, the use of both sewage sludge and rock dust in concrete could save a large amount of freshwater and prevent further depletion of natural aggregates respectively. Moreover, it can be a means of waste disposal and resource recovery.
- compressive strength
- rock dust
- sewage sludge
- First received 23 April 2014.
- Accepted in revised form 2 August 2014.
- © IWA Publishing 2014