The potential of using water purification wastes as fine aggregates in concrete mixes: an initial study

The large quantities of wastes resulting from water purification process (known as sludge) are increasingly becoming a big concern at some of developing countries, where no proper disposal options are available. The traditional practices of sludge disposal through dumping in landfills have become an ecological, environmental and financial burden. This is due to the daily operation, limited capacity of landfills, and negative impacts on soil, climate, surface and ground water. Hence, the goal of this research is to investigate the possibility of using incinerated sludge produced from water purification plants in construction field, and analyzing its effect on mechanical properties of concrete as one of sludge management options. Sludge was incinerated at a temperature of 800 degrees C for two hours, grinded, sieved and replaced by fine aggregate at percentages of 5%, 10%, 15%, and 20% in concrete mixes. XRD and XRF tests were performed to identify crystalline phases and chemical composition of the sludge. The effect of using the incinerated sludge on workability, density, compressive and flexural strengths of concrete at curing ages of 7, and 28 days was investigated. The results showed a significant improvement in compressive and flexural strengths for all samples containing sludge for both curing ages in comparison to control samples, while a reduction in workability was observed.