Mezclas ternarias de cemento Portland, cemento de aluminato de calcio y sulfato cálcico: mecanismos de expansión

• Autores: David Torrens Martín
• Directores de la Tesis: Lucía Fernández Carrasco (dir. tes.)
• Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2013
• Idioma: español
• Tribunal Calificador de la Tesis: María Teresa Blanco-Varela (presid.), Miren Etxeberria Larrañaga (secret.), Sagrario Martínez Ramírez (voc.), Francisca Puertas Maroto (voc.), Joan Lluís Zamora i Mestre (voc.)
• Materias:
  • Ciencias tecnológicas
    • Tecnología de materiales
    • Tecnología e ingeniería mecánicas
      • Material de construcción
• Enlaces
  • Tesis en acceso abierto en: TDX
• Resumen

  • Portland cement is the most widely used building material. Is mainly composed of silicates, also has lesser proportion of aluminates and calcium sulfate. Its hydraulic nature generates in its hydration, the formation of new phases which provide properties (hardness, resistance...) very useful in the field of construction. Calcium aluminate cement is mainly composed of aluminate. Present a faster setting and resistance development higher than Portland cement. Its hydration provides different phases depending of the temperature. This fact provides conversion reactions with a volume decrease causing a resistance decrease. For generate a new properties or improve some of them, exist a wide range binders materials formed for one o few cements with diverse additions. The different combinations provide a variation in the hydrated phases produced which generate changes in the mechanical properties of binders materials. Ternary systems formed by CP/CAC/CS, have been used to produce mixtures with different setting and hardened properties than separately cements. However, within of building materials, the applications of these systems are limited at insides due to durability problems. This work studies the Portland cement rich zone within of ternary systems. Noting the hydrated phases formation, in special ettringite and relationship with dimensional variations which be produced. Generally is observed which an increase in the ettringite formation provides a higher dimensional variation. Ettringite formation is function of CP/CAC and CAC/CS ratios. The amount of aluminates and sulfates control the formation of this phase, if the sulfate present do not consumed all aluminates, these reacts with the ettringite to form monosulfoaluminate decreasing the expansion. In the contrary the amount of sulfate is high the ettringite formation higher and provides higher dimensional variation, that percentages up to 5% generates fissures. Also was verified that environmental of cured have influence in the dimensional variation. Samples with the same cement proportion and calcium sulfate have a different variation. When are cured at air be produced retraction, but when is cured under water be produced expansion. This fact may due at differences in the interlayer of the C?S?H, being more voluminous in the samples submerged per the inclusion of water molecules.