Nature and concentration effect of stabilizing elements of beta-dicalcium silicate on its hydration rate

Efecto del ZnO, ZrO₂ y B₂O₃ en el proceso de clinkerización. Parte I. Reacciones de clinkerizacion y composición de los clínkeres

“…The decline in the tricalcium silicate and the increase in dicalcium silicate contents was due to the destabilizing effect of boric oxide on the C 3 S phase and its stabilizing effect on C 2 S. These results were confirmed by the high CaO free content exhibited by clinkers Cl-5 (0.5% B 2 O 3 ) and Cl-6 (2.0% B 2 O 3 ) (see Figure 2). The stabilizing effect of boric oxide has been reported by other authors (15,17 showed that the stabilized form was β-C 2 S; no other high temperature polymorphs were observed. No flux effect was found for this oxide in the present study, perhaps due to its partial volatilization at the clinkerization temperature (1450 ºC).…”

“…En el clinker con la adición de 0,5% de ZrO 2 se observan cristales de alita con un tamaño entre 5 y 15 µm y de 20-30 µm para el clinker con el 2% de óxido. (15,17). De acuerdo a la bibliografía el óxido de boro puede estabilizar formas polimórficas del C 2 S de alta temperatura (17).…”

“…(15,17). De acuerdo a la bibliografía el óxido de boro puede estabilizar formas polimórficas del C 2 S de alta temperatura (17). Los resultados obtenidos por DRX para los clínkeres Cl-5 (0,5% B 2 O 3 ) y Cl-6 (2% B 2 O 3 ) muestran que la forma estabilizada es el β-C 2 S, no observándose otras formas polimórficas de alta temperatura.…”

Leaching Dicalcium Silicates from Iron Ore Sinter to Remove Phosphorus and Other Contaminants.

“…13) 2) They are relatively unstable, suffering from five temperature/composition/microstructure dependent phase transitions between a, aЈ H , aЈ L , b and g polymorphs, 30,31,33,35) which can be accompanied by significant volume changes that are known to cause the phase to break down or 'dust' in some cases. 30,39) 3) C 2 S is known to incorporate a wide variety of impurities in several different systems, including those relevant to the cement industry [39][40][41] and steelmaking slags, where they preferentially concentrate undesirable components. [36][37][38] 4) The incorporation of impurities in the crystal lattice can stabilise different polymorphs of C 2 S and thereby inhibit phase transformations.…”

“…[36][37][38] 4) The incorporation of impurities in the crystal lattice can stabilise different polymorphs of C 2 S and thereby inhibit phase transformations. 39,41) 5) At least one polymorph of C 2 S (b) is known to gelatinise in dilute HCl 42) and the hydration of C 2 S is well understood in the cement industry. 32,40,41) 6) C 2 S is less dense than many other phases present in iron and steelmaking processes and segregates in ironrich melts by floating.…”