EFECTO DEL USO DE ÁCIDO CÍTRICO SOBRE LA RESISTENCIA A LA COMPRESIÓN DE UN CEMENTO DE SULFOALUMINATO DE CALCIO SINTETIZADO A PARTIR DE DESECHOS INDUSTRIALES A 1100 °C

Abstract

In this work the development of compression strength of calcium sulphoaluminate (C4A3ᡅ ), pastes of a clinker produced from fly ash, aluminum dross and fluorgypsum at a temperature of 1100 °C, was evaluated. Cement pastes were prepared with or without citric acid addition (0.05 wt %), adding 15 wt. % of gypsum based on the anhydrite amount and adjusting the amount of CaSO4•1/2H2O (15 wt % of gypsum) based on the amount of cementive phase. The compressive strength was evaluated after 1, 3, 7, 14, 28 and 90 days of curing at 20 °C. The compressive strengths were 33.30 and 35.70 MPa for the samples without additive. The systems with additive developed 46.71 and 49.43 MPa after 90 days of curing. These values were higher from a CPO system that reached a 44.28 MPa after 90 days. The XRD results showed that after the synthesis the main phases detected were calcium sulphoaluminate, gehelenite and mayenite. Scaning electron microscopy analysis showed that the morphology of the samples showed plates and acicular particles which are characteristically from the ettringite formation, and small white nodules corresponding to gypsum.