Avaliação da eficiência de utilização da cinza de lodo de ETEs como substituição parcial ao Cimento Portland na produção de concretos

Abstract

The metropolitan region of Recife currently has around 3,800 people and presents problems common to any large urban center, such as those related to the generation of solid waste, particularly that resulting from the treatment of domestic sewage. Currently, sewage treatment reaches only 33% of the population in this area, however the guidelines of the New Sanitation Legal Framework imply the need to increase this service to the level of 90% in the next 14 years, maintaining it at this level from then on. Under these conditions, the aim is to reach the mark of 5 million people served with sewage by 2047. Given this fact, the production of sewage sludge, which is currently difficult to dispose of, will increase by 190% in this period, making studies relevant that guarantee a destination for the waste with the least possible impact on the environment. This is the fundamental purpose of this study – to point out an alternative for this

destination. For this purpose, two classes of concrete were produced (structural and non- structural), consisting of four families each. In these four families, one was taken as a reference

and the other three were produced with percentages of cement replacement by sludge ash at levels of 5%, 8% and 12%. For the fresh state, properties such as workability and specific mass were verified and for the hardened state, resistance to compression, traction by diametrical compression and water absorption by capillarity were verified. There were no relevant changes caused using ash in relation to workability or specific mass. In the hardened state, the replacement percentage of 8% showed the best results in the compressive strength test, both for the compressive strength and the tensile strength tests, regardless of the class of concrete analyzed. In capillarity water absorption tests, the behaviors were similar between structural and non-structural concrete. Also in this case, the 8% replacement content led to the best result (lower absorption). This not only revealed the excellent potential for using sludge ash from sewage treatment plants as a mineral addition to produce concrete, but also identified that such use, especially at an 8% replacement level, would not compromises the performance of the concrete produced, representing yet another contribution from the construction industry to strengthening the circular economy linked to the sanitation chain