Avaliação do uso de cinzas de incineração de resíduos perigosos na produção de argamassa para concreto

Abstract

The inadequate handling and disposal of solid waste (SW), especially hazardous waste (HW), can have harmful consequences for the environment and public health. In Brazil, this concern has been gaining importance through the legal guideline that institutes the national solid waste policy (NSWP), encouraging the implementation of processes that carry out the proper treatment and disposal of generated waste. That way, the objective of this research was to evaluate the by- product (ash) from the incineration of HW applied in cement matrices by partial replacement of Portland cement and/or fine aggregate. The material studied was bottom ash (BA) from an incinerator located in the state of Bahia/Brazil, which calcined at 1000°C in the laboratory, generated calcined ash (CA). The BA and CA ashes were submitted to physical-chemical and mineralogical characterization tests, such as X-ray diffraction (XRD), X-ray fluorescence (XRF), Fourier transform infrared (FTIR), thermal analysis (TGA and DTA), microstructure analysis (SEM- EDS), plasma element leach extracts (ICP-MS), laser particle size distribution, specific mass, specific surface, loss on ignition (LI), total organic carbon (TOC) , pozzolanic activity tests (Frattini, Luxán, XRD and NBR 5752/2014), determination of consistency index (CI), compressive strength (CS) and apparent porosity (AP) applied to pastes and mortars with individual use of CA or in composition of CA+ limestone filler (LF). The results obtained indicate physical characteristics of specific mass of the order of 2,80 g/cm3 for CA, LI and TOC accentuated by 47% in BA and 2% in CA, chemical composition with the presence of Al2O3, SiO2, CaO, Fe, Ag among other trace elements and moderate pozzolanic activity. In the leachate extracts, the presence of heavy metals was not detected, with the presence of the elements Ca, Al, Fe, K, Na and Ag in concentrations below the norm in Brazil, and transfer rates in higher order of CA in relation to BA. The use of the different techniques and methods implemented, allowed to expand the knowledge of the residue under study, indicating that the incorporation of the percentage of 5% of CA in mortar for concrete did not compromise the characteristics of CS and AP and had satisfactory performances. The incorporation of CA in mortars will reduce the volume of final disposal of this waste in landfills, energy gains, reduction of cement production/consumption positively impacting the reduction of CO2 emissions in the atmosphere, reduction of fine aggregate extraction and perhaps gains economic with a residue that currently generates expenses transforming into return adding to activities related to civil construction.