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

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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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Available from: D. Benavente, Apr 06, 2014
    • "These limestones mainly have interparticle porosity. L8 and L9 are detrital limestones (biocalcirrudites) composed of large allochem grains (mainly bivalves, bryozoans and red algae) (Benavente, 2003). L10 is a biomicrite composed of oriented fragments of fossils (mainly ostracods and molluscs), which, consequently, provide a structural anisotropy to the rock. "
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    ABSTRACT: In this paper, absolute water permeability is estimated from capillary imbibition and pore structure for 15 sedimentary rock types. They present a wide range of petrographic characteristics that provide degrees of connectivity, porosities, pore size distributions, water absorption coefficients by capillarity and water permeabilities. A statistical analysis shows strong correlations among the petrophysical parameters of the studied rocks. Several fundamental properties are fitted into different linear and multiple expressions where water permeability is expressed as a generalized function of the properties. Some practical aspects of these correlations are highlighted in order to use capillary imbibition tests to estimate permeability. The permeability–porosity relation is discussed in the context of the influence of pore connectivity and wettability. As a consequence, we propose a generalized model for permeability that includes information about water fluid rate (water absorption coefficient by capillarity), water properties (density and viscosity), wetting (interfacial tension and contact angle) and pore structure (pore radius and porosity). Its application is examined in terms of the type of pores that contribute to water transport and wettability. The results indicate that the threshold pore radius, in which water percolates through rock, achieves the best description of the pore system. The proposed equation is compared against Carman–Kozeny's and Katz–Thompson's equations. The proposed equation achieves very accurate predictions of the water permeability in the range of 0.01 to 1000 mD.
    No preview · Article · Sep 2015 · Engineering Geology
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    • "The fluid transport properties of building stones are one of the most important factors determining their durability. Fluid transport may favour weathering processes such as freezethaw crystallisation pressure, hydration pressure, and salt precipitation (Benavente, 2003). Currently, in the construction and building material sector, research into transport properties is extensively focused on unsaturated flow models (see Ioannou et al., 2004; Ruíz de Argandoña et al., 2004; Benavente et al., 2002; Mosquera et al., 2000). "
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    ABSTRACT: Three kinds of brecciated dolostones (BD) from the Betic Cordillera (Spain) marketed as commercial marble and extensively used as construction and building materials were studied in order to describe their water transport properties. Water permeability and capillary imbibition test were undertaken in order to determine the influence of pore structure on water transport within these types of stones. These BD are commonly known in the commercial sector as Marrón Emperador (ME), Beige Serpiente (BS) and Amarillo Triana (AT). In general terms, they are all mesocrystalline dolostones with different degrees of fissure density. These fissure systems are frequently filled with mineral calcite and dolomite cement and sometimes present evidence of strong dissolution processes. Spatial distribution of textural components differs significantly according to the variety studied. A correlation between water permeability and other physical properties is discussed, including both pore structure (porosity and pore size distribution) and fissure geometry (width and density). Since permeability is a directional quantity, it has been measured in three orthogonal directions, together with the other parameters. In order to establish a relationship between all parameters, multivariate statistical tools have been applied. The mercury intrusion porosimetry results defined two kinds of porous family: matrix/cement (porous space) and fissures. Moreover, we found that the permeability logarithm correlates with fissure density (~70%) and is independent of both porosity and fissure width. Furthermore, principal component analysis corroborates permeability dependence on fissure density and suggests strong influence of mean porous size on permeability. The anisotropic index estimated for ME and AT is quite some distance from 1, indicating strong anisotropic permeability, whereas for BS it is nearer to 1, denoting isotropic permeability behaviour.
    Full-text · Conference Paper · Jun 2007
    • "The amount of cracks and fractures can be considered negligible in the stones studied (Benavente, 2003). A detailed summary of the nature, approximate quantity and mode of the clasts, as well as the type of porosity and cement and matrix of the studied stones are shown in Table 1 "
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    ABSTRACT: The influence of both pore structure and strength on the estimation of stone durability is evaluated. Salt crystallisation may limit the durability of porous building stones because it can be considered as one of the most powerful weathering agents. Salt crystallisation produces stress over the pore surface. Consequently, stone durability is closely related to both pore structure and strength, which is the material resistance to crystallisation pressure. We propose a novel petrophysical durability estimator (PDE) as the ratio between parameters and estimators, which are based on pore structure and the strength of the material.In this study, we have used stone parameters and estimators that have an influence on durability and depend only upon pore structure, i.e., connected porosity, water absorption, the water absorption coefficient, specific surface area (SSA), the saturation coefficient, the durability factor, the durability dimensional estimator (DDE) and others derived from porosity, such as microporosity and adjusted microporosity. We also used stone parameters and estimators with an influence on strength: flexural strength, uniaxial compressive strength, Young's dynamic modulus and compressional wave velocity. These parameters and estimators, and the proposed petrophysical estimator are compared with a salt weathering test. Our study shows that there is a very strong correlation between salt weathering and the proposed petrophysical estimator, whereas only moderate correlation exists with the estimators that depend on pore structure and strength. We conclude that the proposed estimator contains the information necessary to understand and estimate the durability of porous materials which have an impact on buildings, civil constructions and historical monuments.
    No preview · Article · Jul 2004
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