Feasibility of using industrial boiler ash in the dosing of structural concrete

Industrialization and accelerated population growth generate side effects on various social aspects, and the environmental issue is worrisome due to the impacts caused by social evolution. The management of industrial waste is a great challenge that involves both control of its generation and the proper disposal, ensuring environmental sustainability. Boiler ash residue is found in abundance in factories that use this equipment for steam generation. This abundance occurs due to the lack of a place for proper disposal or reuse of the residue. In view of this scenario, this article had as a guide question: Would it be possible to use this residue in the production of structural concrete? The aim of this study was to classify the residue by defining its possible form of use in concrete dosage and to perform experimental dosages with the use of industrial boiler ash to evaluate its possible technical contributions to basic properties of concrete. For this, samples were collected by an industry installed in the city of Uberlândia, State of Minas Gerais, active in several sectors such as agriculture, animal nutrition, pharmaceutical and others. The classification of boiler ash was performed by applying the Brazilian normative procedures and parameters used for classification of binders and aggregates for concrete. Considering its granulometric curve and density, the residue was classified as light and very thin aggregate, thus adopting the methodology of partial replacement of the thin aggregate by boiler ash. It was verified that there was a reduction in the workability of concrete in the fresh state proportionally to the residue content used. Therefore, it is necessary to use superplasticizer additives in these cases to maintain the expected workability. A reduction in the density of concrete was noticed when the residue was used, considering as necessary the attention to this property of the concrete in relation to the content used of the residue in the dosage. It was also observed when comparing the dosages with the use of the residue at the standard dosage, that there was a reduction in compressive strength. However, there was no great variation in compressive strength between the dosages with different substitution levels used. It was concluded, therefore, considering the levels used in this study, as feasible the use of this residue in the production of structural concrete.