Sludge Use in Concrete as a Replacement of Cement

Sludge is an unavoidable product of wastewater treatment that creates problems of disposal. Increasingly, strict environmental control regulations have resulted in limitations on sludge disposal options. Disposal by incineration has been found to be a good option. In this research, application of waste sludge were collected from sewage treatment plant (STP) Nashik was used as cement replacement in concrete mix. This study utilized replacement of 5%, 10 %, 15 % and 20% by weight of OPC with water binder (w/c) ratio of 0.50 and 0.45 for Grade 20 and Grade 30 respectively. The performance of sludge concrete in terms of its compressive strength, split tensile strength test, flexure strength test were investigated. All values of compressive strength for sludge concrete were lower compared to the OPC control, and the strength decreased as the percentage of replacement with sludge increased for Grade 20 and Grade 30, at replacement of 10 %. Meanwhile, water absorption and water permeability for the sludge concrete increased as the replacement increased. Overall, with further research in producing quality, the potential of using this waste as a cement replacement material is very promising.