Utilization of wastewater sludge for lightweight concrete and the use of wastewater as curing medium

The increasing population have resulted in a higher generation of domestic and industrial wastewater sludge. The sludge ends up as a landfill in designated areas which makes the land unusable. The search for lightweight materials for construction has led to the use of sludge as a viable replacement for the basic composition of concrete due to its low density. The dry sludge collected from Polokwane Waste Water Treatment Works (WWTW) in Limpopo Province was used as a partial replacement of sand in concrete. The sludge content in the sand was varied from 2.5, 5, 7.5, 10, to 12.5 %. The outcomes of the analysis indicate that the partial replacement of sand with dry sludge in the concrete mix is viable and useful. The result showed that up to 7.5 % of sand could be replaced with dry sludge in concrete for structural applications. Also, wastewater can be used as a curing medium. The unit weight of the concrete decreased with increasing sludge content, which was attributed to the lower density of the sludge. The SEM image revealed a porous nature and irregular surface morphology of the sludge and the concrete.

Automated summary

As the population grows, there is an increase in domestic and industrial wastewater sludge, leading to its disposal in designated landfills. The use of sludge as a partial replacement for sand in concrete has been shown to be viable, with up to 7.5% replacement being suitable for structural applications. The density of concrete decreases with higher sludge content, attributed to the porous and irregular surface morphology of the sludge and concrete.