8 results on '"Porosity"'
Search Results
2. Investigation of the Porosity Structure in the Ceramic Wall Material of the Fortress in Girona (Spain).
- Author
-
Abdrakhimova, E. S. and Abdrakhimov, V. Z.
- Subjects
- *
POROSITY , *DISTRIBUTION (Probability theory) , *CERAMIC materials , *PORE size distribution - Abstract
The object of investigation is the ceramic material taken from the fortress wall in the city of Girona. The chemical composition of the researched material showed a heightened content of carbon (13.1%) in it, attesting the introduction of fuel into the green body. The heightened content of fuel in the green body promotes porosity formation and uniform sintering inside the ceramic sample. The integral and differential programs of the research samples, which were obtained by means of mercury porosimetry, showed that the total volume of the micropores ranging in size from 10 – 4 to 10 – 8 m is equal to 0.155 cm3/g. The differential distribution of micropores as a function of their size is: 10 – 4 – 10– 5 — 27% (reserve – non-hazardous); 10 – 5 – 10– 6m— 19% (hazardous); 10 – 6 – 10– 7 m — 29%; 10 – 7 – 10– 8 m — 25% (non-hazardous). [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
3. Karst massif susceptibility from rock matrix, fracture and conduit porosities: a case study of the Sierra de las Nieves (Málaga, Spain).
- Author
-
Pardo-Igúzquiza, Eulogio, Durán, Juan, Luque-Espinar, Juan, Robledo-Ardila, Pedro, Martos-Rosillo, Sergio, Guardiola-Albert, Carolina, and Pedrera, Antonio
- Subjects
AQUIFERS ,KARST ,ROCK mechanics ,CARBONATE rocks ,FRACTURE mechanics ,POROSITY - Abstract
The potential contamination of a karst massif from surface sources can be evaluated and represented in a susceptibility map. In the case of a carbonate aquifer, the susceptibility assessment must take into account their very complex and heterogeneous nature. The complexity originates in the presence of three types of porosity: matrix rock, fracture and conduit porosity. This paper presents a method for karst susceptibility mapping by estimating the three porosity types and evaluates their integration in a single susceptibility index. Matrix rock porosity is measured in the laboratory from samples collected in the field and is well correlated with lithology. Fracture porosity is estimated from fracture mapping and field measurements of secondary fracture porosity. Geostatistical methods are used to obtain continuous fields of rock matrix porosity and fracture porosity. Conduit porosity is calculated from a power model fitted to speleological cave mapping data. However, because of the scarcity and sampling bias of conduit data, probabilistic models are conjectured. A fourth porosity factor evaluated is the detritic filling of karst depressions. The integration of the different porosities in a single susceptibility factor gives a quantitative map that is reclassified to provide a qualitative, easy to interpret susceptibility index map of the karst system. Porosity estimation may also be of interest in recharge estimation and mathematical modelling of flow and transport in karst systems. The case study used to illustrate this approach is the Sierra de las Nieves karstified rock mass, a high relief Mediterranean karst in the province of Málaga in southern Spain. [ABSTRACT FROM AUTHOR]
- Published
- 2015
- Full Text
- View/download PDF
4. Assessment of the physico-mechanical behaviour of gypsum-lime repair mortars as a function of curing time.
- Author
-
Igea Romera, Jesús, Martínez-Ramírez, Sagrario, Lapuente, Pilar, and Blanco-Varela, María
- Subjects
CURING ,MORTAR ,CARBONATION (Chemistry) ,POROSITY ,MAINTENANCE - Abstract
Gypsum-based mortars were widely used during the Mudejar artistic period in Spain from the 12th to 16th century. During restoration works, compatibility between the new repair mortars and the original components is essential for an adequate intervention on the monument. The increasing interest of knowing the properties of the gypsum-lime-based mortars for restoration purposes justifies the research carried out. Different mortars compatible with traditional building materials were elaborated by varying the binder proportions, the type of aggregates, the binder/aggregate ratios and the curing time. The main goal of this paper is to characterize the mechanical behaviour and the pore structure of the mortars as a function of curing time. The influence between the different variables used to prepare the mortars and the development of the carbonation process over time is also considered. Mechanical strength and porosity measurements as well as X-ray diffraction and thermal analysis were performed after curing times of 1, 28 and 90 days. The results obtained confirmed a progressive increase in mechanical strength linked to the carbonation of the mortars prepared. Less lime binder and also aggregate contents showed the highest rise in strength over time, related to the highest initial porosity which favoured the carbon dioxide flow. The use of siliceous aggregates (GL-QS mortars) obtained the best results in the development of physico-mechanical properties over curing time. The knowledge obtained from the studied mortars provides practical information to establish a suitable mortar mixture for restoration works on historic buildings and modern architecture where gypsum-lime-based mortars are used. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
5. Importance of porosity and transfer of matter in the rock weathering processes: two examples in central Spain.
- Author
-
Molina Ballesteros, E., García Talegón, J., Iñigo Iñigo, A., González Sánchez, M., and Herrero Fernández, H.
- Subjects
GRANODIORITE ,SLATE ,ROCKS ,POROSITY - Abstract
Some physical properties (bulk and free porosity, pore size distribution), and the chemical composition and mass balance of two deeply weathered profiles one developed on Hercynian granodiorite and the other on pre-Cambrian slates were studied. Hydric and mercury porosimetry, nitrogen adsorption techniques, chemical analyses and XRD techniques were used. On granodiorite, weathering has created increased porosity with a pore diameter <5 μm, whereas on slates the weathering has produced of ca. 1 μm in diameter. These pore sizes have played an important role in the weathering processes. Assuming that weathering preserves volumes, except in the uppermost part of the profiles, it brought about a loss of matter of more than 12% (~300 kg/m) on granodiorite and ca. 30% (~800 kg/m) on slates. These changes are related to shifts in the mineralogical evolution, with the appearance of new 2:1 and 1:1 phyllosilicates and Fe oxy-hydroxides as the main authigenic minerals. The release of matter, at least since the upper Neogene until the present, has led to the lowering of relief in a more or less homogeneous way, giving rise to gentle hillsides and flat surfaces below which the current river networks are incised. Porosity studies have the potential to explain several specific landforms as well as affecting landscape development in general. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
6. Direct observation of microcrack development in marble caused by thermal weathering.
- Author
-
Luque, A., Ruiz-Agudo, E., Cultrone, G., Sebastián, E., and Siegesmund, S.
- Subjects
MARBLE ,WEATHERING ,THERMAL properties of rocks ,ROCK analysis ,POROSITY - Abstract
One of the properties that makes marble such an excellent construction and ornamental material is its low porosity. It is very difficult for water or decay agents to penetrate the internal structure of materials with no or few pores, so enhancing the durability of these materials. However, environmental temperature fluctuations bring about significant physical changes in marbles that result in an increase in porosity, due to the appearance of new microcracks and the expansion of existing ones. These cracks offer new paths into the marble which make it easier for solutions containing pollutants to penetrate the material. Thermal expansion tests were performed on three different types of marble known as White, Tranco, and Yellow Macael (Almeria, Spain), after which an increase in porosity (from 17 to 73% depending on marble type) was observed, mainly due to crack formation. The structural changes occurring during thermal expansion tests were more significant in the case of White Macael samples, a fact that is not only related to its mineralogical composition but also to the morphology of the grains, grain boundaries and crystal size. Our research suggests that thermally weathered White Macael marble could be more susceptible to decay by other contaminant agents than Tranco or Yellow Macael. The use of hot-stage environmental scanning electron microscopy is proposed as a valid tool for observing, both in situ and at high magnification, changes in the fracture system of building stones induced by thermal stress. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
7. Hydrodynamic characteristics and sustainable use of a karst aquifer of high environmental value in the Cabrejas range (Soria, Spain).
- Author
-
Pérez, Juan and Sanz, Eugenio
- Subjects
HYDRODYNAMICS ,KARST ,AQUIFERS ,WATER supply ,POROSITY - Abstract
This paper describes the research carried out in a karst aquifer located in Soria, Spain. The system presents considerable good-quality water resources, yielding a series of springs which constitute a 'Natural Monument'. An integral study of the hydrological cycle is presented in order to characterize the hydrodynamic behavior of the aquifer. Research combines conventional geological and hydrogeological approaches with more innovative techniques such as speleo-diving. On the basis of relatively little available data, quantitative results are obtained. These include estimations on porosity, hydraulic conductivity, transmissivity, and groundwater renewal rate and aquifer reserves. A vulnerability assessment is carried out to evaluate the potential effects of overpumping. This is followed by a proposal for sustainable aquifer management. Since aquifers such as the one in this study are frequently found, this methodology could be successfully extrapolated to other cases. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
8. Roman ceramics of hydraulic mortars used to build the Mithraeum house of Mérida (Spain).
- Author
-
Franquelo, M., Robador, M., Ram#x00ED;rez-Valle, V., Dur#x00E1;n, A., Jim#x00E9;nez de Haro, M., and P#x00E9;rez-Rodr#x00ED;guez, J.
- Subjects
- *
FIRING (Ceramics) , *MORTAR , *X-ray diffractometers , *QUARTZ , *POROSITY - Abstract
Roman ceramics of two hydraulic mortars used to build the pond and water channel of Mithraeum house from Mérida (Spain) have been studied. The sizes of the ceramic fragments found were different in both of the samples studied, showing different behaviour in the reactions with the lime. The X-ray diffraction of the ceramic shows the presence of quartz, mica (biotite), anorthite and hematite accompanied by amorphous phase, being observed scarce vitrification. The presence of mica confirms a firing temperature for manufacturing the ceramic below 900°C. In one of the ceramics studied, X-ray diffraction did not show calcite. However, in the FTIR appear bands that could be assigned to carbonates absorptions and likewise, carbonates were identified in the DTA-TG curves. Ca and small quantities of Si and Al were also identified by SEM-EDX on the surface of the pores that could be due to an amorphous phase formed in the reaction of lime with the Si and Al of the ceramic. On the other hand, in other ceramic samples carbonates (about 10%) were detected. The carbonates have been found filling the pores, sometimes accompanied by a new calcium-aluminium-silicate phase produced by the reaction between the lime and the amorphous phase of the ceramic. The carbonates and the new phases formed inside the pores are responsible for the decrease of the porosity and for the formation of new phases during the heating of the ceramics. [ABSTRACT FROM AUTHOR]
- Published
- 2008
- Full Text
- View/download PDF
Catalog
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.