Síntese e caracterização das fases minerais C3S, C2S, C3A e C4AF para utilização em cimento tipo Portland

Abstract

ResumoAs principais fases contidas no cimento Portland são 3CaO.SiO 2 (C 3 S), 2CaO.SiO 2 (C 2 S), 3CaO.Al 2 O 3 (C 3 A) e 4CaO.Al 2 O 3 .Fe 2 O 3 (C 4 AF). No processo industrial estas apresentam incorporações de outros elementos que dependem das matérias-primas e dos combustíveis utilizados na queima. O uso das fases puras auxilia na compreensão dos fenômenos envolvidos no estado fresco e endurecido, porém sua produção isolada exige condições específicas. O objetivo foi realizar a síntese das fases com o intuito de obter a menor quantidade de polimorfos e CaO. Na caracterização das fases químicas foram utilizadas as análises de granulometria a laser, fluorescência de raios X e difração de raios X com a quantificação das fases pelo método de Rietveld. Foi obtida elevada pureza para o C 4 AF e o C 3 A. O C 3 S e o C 2 S apresentaram apenas um polimorfo, porém elevados teores de CaO, 4,9 e 5,1%, respectivamente. Palavras-chave: síntese, cimento Portland, clínquer, polimorfismo. AbstractThe main phases contained in the Portland cement are 3CaO.SiO 2 (C 3 S), 2CaO.SiO 2 (C 2 S), 3CaO.Al 2 O 3 (C 3 A), and 4CaO.Al 2 O 3 . Fe 2 O 3 (C 4 AF). In the industrial process, these phases present incorporations of other elements that depend on the raw materials and the fuels used in the firing. The use of the pure phase helps in understanding the phenomena involved in the fresh and hardened state, however their isolated production requires specific conditions. The objective of this research was to perform the synthesis of the phases in order to obtain the minimum of polymorphs and CaO. In the characterization of the chemical phases obtained, the laser particle-size analysis, X-ray fluorescence and X-ray diffraction with the quantification by Rietveld method were used. High purity could be obtained for C 4 AF and C 3 A. The C 3 S and C 2 S phases had at most one polymorph, but high levels of CaO, 4.9 and 5.1%, respectively.

Numerical analysis of the thermal profile inside the wall of a rotary cement kiln

“…Cement production is continually expanding, and one of the industry's key challenges is dealing with high energy consumption and reducing the environmental impacts caused by the process [1]. Therefore, there has been a constant concern to understand, model, and optimize the cement production process in order to reduce its environmental impact [2][3][4][5]. Portland cement is the most widely used type of cement in the world and can be applied to the construction of houses, buildings, bridges, and other structures [6].…”

Cementing Process in the Presence of Fluid Loss

“…Finally, cement slurry is considered to present shrinkage during setting period, which is a density change with time observed by many authors in the literature [28,142,27]. Hypothesis (vi) implies that cement fraction density is a function of time, as showed in Eq.…”

“…Calcium silicate hydrate is mostly the responsible for cement-base concrete strength. Although this work does not explore further chemical aspects, such as the detailed reaction stoichiometry or a deep sensitivity analysis on composite fractions, some interesting discussions on this topic were presented by Kunther et al [27] and Barbosa [28].…”

Influência Da Incorporação Do Rejeito De Minério De Ferro Nas Propriedades Químicas, Físicas E Mecânicas Do Concreto

“…Na Figura 39c, percebe-se a presença de picos bem definidos e a ausência de desvio na linha de base (halo amorfo), indicando o alto grau de cristalinidade do RMF [217], [218]. temperaturas inferiores a 500 ºC) [59], [219], [220].…”