ANALYSIS OF THE EFFLORESCENCE FORMATION IN RED CERAMICS WITH INCORPORATIONS OF STEEL WASTE AFTER WASHING PROCESS

Reference	Presenter	Authors (Institution)	Abstract
16-071	Danilo Silva Luz	Luz, D.S.(Universidade Federal do Sul e Sudeste do Para); Barbosa, A.C.(Universidade Federal do Sul e Sudeste do Pará); Sousa, R.C.(Universidade Federal do Sul e Sudeste do Pará); Fagury Neto, E.(Universidade Federal do Sul e Sudeste do Pará); Rabelo, A.A.(Universidade Federal do Sul e Sudeste do Pará);	The soluble salts are the main cause of the degradation by efflorescence in the ceramic materials. This phenomenon, besides affecting aesthetically, causes problems of insalubrity and accelerates the deterioration of the contaminated materials. Blast furnace slag and dedusting powder from steel production are solid waste that requires correct environmental management. This work studied the formation of efflorescence in red ceramics, with additions from 3 to 12 wt% of blast furnace slag and 5 to 35 wt% of the electric arc furnace dedusting powder into the clay mass after the washing processes of tailings. Test pieces were made in uniaxial press at 55 MPa with 60 x 20 x 4 mm, which were calcined at 400 °C in the muffle furnace for two hours and sintered at temperatures of 800, 850 and 900 °C for two hours. After burning, linear retraction, water absorption, apparent porosity and apparent density were characterized by the Archimedes method. For the efflorescence test, 80% of the length of the specimen was immersed in distilled water for one week, and then kept in a drying oven at 110 °C for 24 h to accelerate the formation of the efflorescence. The microstructural characterization was carried out by scanning electron microscopy and the quantification of the salts through electrical conductivity of the samples. The Image J software was used for verification and quantification of the efflorescence, being verified that dedusting powder was the one with the highest efflorescence indexes, while this phenomena with blast furnace slag samples was virtually imperceptible. The washing of the dedusting powder had a great effect on the reduction of efflorescence in the proof bodies, eliminating approximately 96% in the formation of the efflorescence.
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