Modelización y estimación de la durabilidad de materiales pétreos porosos frente a la cristalización

Source: OAI

ABSTRACT 291 pp.-- Tesis desarrollada en el Departamento de Ciencias de la Tierra y del Medio Ambiente, Facultad de Ciencias, Universidad de Alicante (2002). [EN] In this Thesis, different mechanisms of salt crystallisation are evaluated, and stone durability against salt crystallisation is also quantified. These stones are widely used not only in architectural and cultural heritage but also in modern buildings, used as building material. Three salt crystallisation mechanisms are studied: evaporation process of brines from porous media of rocks; the influence of porous media on the mineral precipitation sequence; and, finally, the crystallisation pressure that mineral growth produces over the pore wall. In order to quantify stone durability, a salt crystallisation test, based on partial immersion of the materials, is proposed. For this purpose, nineteen porous stones have been chosen for their different petrophysical and petrographic characteristics (mainly bioclastic rocks with different grain size); and two brines have also been used for their abundance and aggresiveness: NaCl and Na2SO4. Finally, a durability theoretic estimator is proposed, including parameters of porous media and mechanical properties of rocks. [ES] Los objetivos de esta tesis son (i)modelizar la cristalización de sales en medios porosos mediante el estudio de la saturación de los diferentes minerales que van a crecer en el seno de rocas porosas por evaporación, la determinación experimental de la secuencia de precipitación que se produce en los poros de las rocas proponiendo las ecuaciones básicas que rigen dicho proceso y la determinación de la variación del sistema poroso de la roca por la presión de cristalización, evaluando mediante las ecuaciones teóricas planteadas por Scherer (1999) la influencia de los parámetros más importantes que definen dicha presión: el volumen molar, la tensión superficial cristal-salmuera y la interacción cristal-superficie de la roca. Adicionalmente, esta Tesis pretende cuantificar la durabilidad de las rocas porosas, (i) proponiendo un nuevo ensayo acelerado de cristalización de sales más acorde con las observaciones reales, en contraposición a los ensayos basados en ciclos de inmersión total de la roca en salmuera y (ii) definiendo estimadores teóricos de durabilidad acordes con los mecanismos de degradación de las rocas porosas de construcción por la acción de la cristalización de sales evaluados y cuantificados a lo largo de la tesis doctoral. Esta Tesis ha sido financiada por una beca de formación de personal investigador de la Generalitat Valenciana y por los proyectos: PB96-0321, GV97-RN14-3 y MAT2000-074. Peer reviewed

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