The Experts below are selected from a list of 50349 Experts worldwide ranked by ideXlab platform
N. De Belie - One of the best experts on this subject based on the ideXlab platform.
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Physical evidence of swelling as the cause of anomalous Capillary Water uptake by cementitious materials
Cement and Concrete Research, 2019Co-Authors: Natalia Mariel Alderete, Y. A. Villagrán Zaccardi, N. De BelieAbstract:Abstract Water uptake by capillarity is widely used for characterising the durability properties of building materials. However, cementitious materials are generally reported with an anomalous behaviour in relation to other construction materials: during Capillary Water uptake they show a non-linear evolution with the square root of time. Several hypotheses have been proposed to explain this anomaly, among which the most sound seems to be the hygroscopic nature of cementitious materials, since the swelling of the calcium silicate hydrates when in contact with Water could limit the Water flow. Using strain gauges attached to mortar and concrete samples, we monitored their deformations during Capillary Water uptake. This paper presents those results and their connection with Water ingress. Experimental data registered during Water uptake allow validating the swelling hypothesis. The idea of cementitious materials as rigid materials during Capillary Water uptake seems incomplete for a comprehensive description of the transport process.
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transport properties of high volume fly ash concrete Capillary Water sorption Water sorption under vacuum and gas permeability
Cement & Concrete Composites, 2010Co-Authors: P Van Den Heede, Elke Gruyaert, N. De BelieAbstract:Abstract Studying concrete’s resistance to carbonation-induced corrosion usually involves exposing the material to CO2 for quite some time. To estimate the performance of high-volume fly ash (HVFA) concrete more quickly, two key properties governing this process can be studied, namely Water penetrability and gas permeability. With respect to HVFA mixtures optimized for usage in an environment exposed to carbonation with wetting and drying, we adopted the latter approach. This paper presents a full assessment of concrete mixtures with varying fly ash amounts. A 50% fly ash mixture by mass with a binder content of 400 kg/m3 and a Water-to-binder ratio of 0.4 had a lower Capillary Water uptake (−32.6%), Water sorption under vacuum (−10.7%) and gas permeability (−78.9%) than a proper reference normally used in this environment. The fly ash applied had an excellent quality regarding loss on ignition (3.5%) and fineness (19% retained on a 45 μm sieve).
Lionel Mercury - One of the best experts on this subject based on the ideXlab platform.
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Regeneration of Capillary Water in unsaturated zones
Geochimica et Cosmochimica Acta, 2019Co-Authors: Claudie Hulin, Lionel MercuryAbstract:In porous media subject to drying conditions such as arid regions and excavation zones (deep gas injection or nuclear waste disposal), capillarity is involved in weathering processes because it modifies the geochemical and poromechanical balances within the porous network. Heterogeneous porous media like sedimentary rocks can host significant volumes of tensile Capillary Water in large pore bodies, and the negative pressure within is controlled by Capillary forces exerted at nanometric pore throats. We have developed experiments using synthetic bimodal pore systems conducive to Capillary tension. In microtubes, salts precipitated in an evaporating solution to build a dual-porosity system. A large volume (ø 200 µm) became trapped behind nanometric pores, where high Capillary tension was applied. We investigated the gas-Water interactions there, especially how gas nucleated in the trapped liquid and how it subsequently changed size. After gas nucleation, the decreasing of gas volume that we observed has been attributed to two complementary geochemical effects. On the one hand, the Water’s tensile state increases gas solubility, as predicted by thermodynamics: capillarity is a “gas-in” process. On the other hand, while the total volume of the gas-Water assemblage remains constant, the Water’s molar volume increases by Capillary forces. Consequently, Capillary forces exerted at the nano-throats can (re)induce a superheated monophasic liquid state from a biphasic liquid-gas assemblage even after gas nucleation. Tensions required for gas shrinkage have been estimated at 7 ± 3 MPa and 53 ± 15 MPa. This regeneration process offers opportunities for Water to regularly return to a Capillary state, making the Capillary lifetime less limited than expected. This shows that pore heterogeneity in rocks submitted to drying processes results in tension for Water in pores that is long-lived. As a consequence, capillarity may significantly impact the long-term geochemical budget through its effects on gas and solid solubility and/or poromechanics (compaction, tensile stress, fracturing, etc.), so that it may play an important role in the weathering of drying porous materials.
Mustafa Al-naddaf - One of the best experts on this subject based on the ideXlab platform.
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Quantifying the Influence of Halite and Sylvite Crystallization on Capillary Water Absorption Coefficient of Sandstone
Journal of the American Institute for Conservation, 2011Co-Authors: Mustafa Al-naddafAbstract:AbstractThis study aims to investigate the relationship between two important deterioration factors in porous building materials: the Capillary Water absorption coefficient, or W-value, and the soluble salt content. Capillary Water absorption contributes to the decay of porous stones through transporting Water and dissolved salts. On the other hand, high Capillary absorption may be beneficial in that consolidants may penetrate deeper into the stone. Therefore, it is important to understand Capillary fluid movement and factors related to it. Using 10 sandstone drill-core samples, pure Water penetration was measured for saltfree samples and for samples containing soluble salt of known amount and composition. The mineralogical composition and physical properties of the stone were determined after desalination. The W-value of the samples was determined before and after they were impregnated with measured amounts of NaCl and KCl. The results show that the W-value decreased due to NaCl and KCl crystallization i...
Lynn F. Gladden - One of the best experts on this subject based on the ideXlab platform.
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Magnetic resonance imaging studies of spontaneous Capillary Water imbibition in aerated gypsum
Journal of Physics D: Applied Physics, 2011Co-Authors: Kyung-min Song, Jonathan Mitchell, Hamouda Jaffel, Lynn F. GladdenAbstract:In this paper we investigate both Capillary Water imbibition and the sorptivity of aerated gypsum plaster, and how these sorption characteristics are related to the pore structure of the material. These characteristics are examined by monitoring mass change using the conventional gravimetric method and by obtaining Water content profiles using nondestructive magnetic resonance imaging (MRI) techniques during Capillary imbibition of Water. Here, three different gypsum samples are investigated: one non-aerated reference gypsum sample and two aerated gypsum samples produced with different volumetric air fractions. The Capillary Water absorption into the reference sample follows t 1/2 kinetics (Fickian diffusion), where t is the time of ingress. However, in the aerated gypsum samples there are deviations from t 1/2 kinetics. The MRI results show unambiguously that two wetting fronts advance through the aerated structure ; an observation that cannot be made from the gravimetric data alone. The Water content profiles of the aerated gypsum samples are therefore analysed by treating them as the sum of two separate absorption processes using Sharp Front (SF) analysis. The Capillary Water absorption properties of this material are well described as a parallel combination of fast absorption into fine matrix pores and slow absorption into a modified structure of matrix pores inter-connected to air voids introduced into the slurry by aeration. PACS 47.56.+r. flows through porous media PACS 47.55.nb. Capillary and thermoCapillary flows
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Magnetic resonance imaging studies of spontaneous Capillary Water imbibition in aerated gypsum
Journal of Physics D: Applied Physics, 2011Co-Authors: Kyung-min Song, Jonathan Mitchell, Hamouda Jaffel, Lynn F. GladdenAbstract:In this paper we investigate both Capillary Water imbibition and the sorptivity of aerated gypsum plaster, and how these sorption characteristics are related to the pore structure of the material. These characteristics are examined by monitoring mass change using the conventional gravimetric method and by obtaining Water content profiles using non-destructive magnetic resonance imaging (MRI) techniques during Capillary imbibition of Water. Here, three different gypsum samples are investigated: one non-aerated reference gypsum sample and two aerated gypsum samples produced with different volumetric air fractions. The Capillary Water absorption into the reference sample follows t1/2 kinetics (Fickian diffusion), where t is the time of ingress. However, in the aerated gypsum samples there are deviations from t1/2 kinetics. The MRI results show unambiguously that two wetting fronts advance through the aerated structure; an observation that cannot be made from the gravimetric data alone. The Water content profiles of the aerated gypsum samples are therefore analysed by treating them as the sum of two separate absorption processes using sharp front analysis. The Capillary Water absorption properties of this material are well described as a parallel combination of fast absorption into fine matrix pores and slow absorption into a modified structure of matrix pores inter-connected to air voids introduced into the slurry by aeration.
İbrahim Çobanoğlu - One of the best experts on this subject based on the ideXlab platform.
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prediction and identification of Capillary Water absorption capacity of travertine dimension stone
Arabian Journal of Geosciences, 2015Co-Authors: İbrahim ÇobanoğluAbstract:The Capillary transport mechanism has an important role on natural building stones that could be affected by moisture due to atmospheric conditions. Travertine with its natural porous structure is more sensitive to Water which has a significant impact on durability. One of the important indicators of stone–Water interaction is color variations, while natural stones with high Capillary Water absorption potential are in contact with Water due to atmospheric conditions. As far as Water absorption is concerned, Water absorption by weight (WAW), Water absorption by volume (n, apparent porosity), and Capillary Water absorption (CWA) parameters are in close relation with each other. To develop the relationships between Capillary Water absorption and the other Water absorption parameters, regression and artificial neural network (ANN) analyses were performed. Within the scope of this study, the ANN models with three different input structures were established using various input variables in order to determine the relationship between CWA and the other parameters. The results of the different ANN structures of these models have been calculated and evaluated. For this purpose, travertine samples quarried from Denizli region in Turkey were studied. In order to evaluate the model results of regression and ANN methods, statistical performance evaluation parameters, i.e., the coefficient of correlation (CORR), efficiency (E), and root mean square error (RMSE), were calculated. In both regression and ANN models, reasonable coefficients of correlation were calculated. The Capillary Water absorption test is time consuming. The necessary periodical measurements make the process even more impractical. It is known that Capillary Water absorption is directly correlated with similar Water absorption parameters such as Water absorption by weight and apparent porosity. In this study, the estimation of Capillary Water absorption by means of other Water absorption parameters is proposed. Moreover, there is no proposed classification in literature for natural stones based on their Capillary Water absorption. In the final stage of this study, by using the relationships between porosity and Capillary Water absorption, a Capillary Water absorption classification was proposed for travertine. Proposed classification consists of five categories and Capillary Water absorption coefficient which is ranging between very high (>68 g/m2 s0.5) and very low (<1 g/m2 s0.5). It is thought that this study could provide significant advantages in engineering practice and also make contribution to the related literature.
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Prediction and identification of Capillary Water absorption capacity of travertine dimension stone
Arabian Journal of Geosciences, 2015Co-Authors: İbrahim ÇobanoğluAbstract:The Capillary transport mechanism has an important role on natural building stones that could be affected by moisture due to atmospheric conditions. Travertine with its natural porous structure is more sensitive to Water which has a significant impact on durability. One of the important indicators of stone–Water interaction is color variations, while natural stones with high Capillary Water absorption potential are in contact with Water due to atmospheric conditions. As far as Water absorption is concerned, Water absorption by weight (WAW), Water absorption by volume (n, apparent porosity), and Capillary Water absorption (CWA) parameters are in close relation with each other. To develop the relationships between Capillary Water absorption and the other Water absorption parameters, regression and artificial neural network (ANN) analyses were performed. Within the scope of this study, the ANN models with three different input structures were established using various input variables in order to determine the relationship between CWA and the other parameters. The results of the different ANN structures of these models have been calculated and evaluated. For this purpose, travertine samples quarried from Denizli region in Turkey were studied. In order to evaluate the model results of regression and ANN methods, statistical performance evaluation parameters, i.e., the coefficient of correlation (CORR), efficiency (E), and root mean square error (RMSE), were calculated. In both regression and ANN models, reasonable coefficients of correlation were calculated. The Capillary Water absorption test is time consuming. The necessary periodical measurements make the process even more impractical. It is known that Capillary Water absorption is directly correlated with similar Water absorption parameters such as Water absorption by weight and apparent porosity. In this study, the estimation of Capillary Water absorption by means of other Water absorption parameters is proposed. Moreover, there is no proposed classification in literature for natural stones based on their Capillary Water absorption. In the final stage of this study, by using the relationships between porosity and Capillary Water absorption, a Capillary Water absorption classification was proposed for travertine. Proposed classification consists of five categories and Capillary Water absorption coefficient which is ranging between very high (>68 g/m2 s0.5) and very low (
