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Rock pore structure as main reason of rock deterioration

Ondrášik M., Kopecký M.

Studia Geotechnica et Mechanica

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2014

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Vol. 36, nr 1

79--88

EN

Crashed or dimensional rocks have been used as natural construction material, decoration stone or as material for artistic sculptures. Especially old historical towns not only in Slovakia have had experiences with use of stones for construction purposes for centuries. The whole buildings were made from dimensional stone, like sandstone, limestone or rhyolite. Pavements were made especially from basalt, andesite, rhyolite or granite. Also the most common modern construction material – concrete includes large amounts of crashed rock, especially limestone, dolostone and andesite. However, rock as any other material if exposed to exogenous processes starts to deteriorate. Especially mechanical weathering can be very intensive if rock with unsuitable rock properties is used. For long it had been believed that repeated freezing and thawing in relation to high absorption is the main reason of the rock deterioration. In Slovakia for many years the high water absorption was set as exclusion criterion for use of rocks and stones in building industry. Only after 1989 the absorption was accepted as merely informational rock property and not exclusion. The reason of the change was not the understanding of the relationship between the porosity and rock deterioration, but more or less good experiences with some high porous rocks used in constructions exposed to severe weather conditions and proving a lack of relationship between rock freeze-thaw resistivity and water absorption. Results of the recent worldwide research suggest that understanding a resistivity of rocks against deterioration is hidden not in the absorption but in the structure of rock pores in relation to thermodynamic properties of pore water and tensile strength of rocks and rock minerals. Also this article presents some results of research on rock deterioration and pore structure performed on 88 rock samples. The results divide the rocks tested into two groups – group N in which the pore water does not freeze even when the temperature decreases to –20 ºC, and the second group F in which the pore water freezes. It has been found that the rocks from group N contain critical portion of adsorbed water in pores which prevents freezing of the pore water. The presence of adsorbed water enables thermodynamic processes related to osmosis which are dominantly responsible for deterioration of rocks from group N. A high correlation (R = 0.81) between content of adsorbed water and freeze-thaw loss was proved and can be used as durability estimator of rocks from group N. The rock deterioration of group F is caused not only by osmosis, but also by some other processes and influences, such as hydraulic pressure, permeability, grain size, rock and mineral tensile strength, degree of saturation, etc., and the deterioration cannot be predicted yet without the freeze-thaw test. Since the contents of absorbed water and ratio between adsorbed and bulk water (of which the absorbed water consists) is controlled by the porosity and pore structure, it can be concluded that the deterioration of some rocks is strongly related to rock pore structure.

2

Metoda biplot w interpretacji danych złożonych (CDA) w geologii

Labus K., Labus M.

Przegląd Geologiczny

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2010

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Vol. 58, nr 5

436-442

EN

Compositional data consist of compositions of parts summing to some whole (e.g.: 100%, 1). Such "closed" data are very popular in geochemistry, sedimentology, hydrogeology and environmetrics. This paper presents the data visualization method by means of the biplot method - a statistical technique widely applied in Compositional Data Analysis. This method enables a graphical display of observations and variables on the same chart, in a way that approximates their correlation. In a biplot the observations are marked with points, and variables - by rays emanating from the origin. Both their lengths and directions are important to the interpretation. The paper presents two examples of implementation of biplots in analysis of hydrogeological and petrological data. The first example concerns petrological data set for pores and skeleton grains of different Polish sandstones. The biplot visualization unveiled a possible independence of subcompositions of transitional pores (T) and macropores (R), as well as submacropores (S) and skeleton grains (Re). The use of this method made it also possible to demonstrate the rule according to which the share of transitive pores decreases at the advantage of real macropores from younger to older rocks, what is related to diagenesis processes. The second example concerns interpretation of hydrological data on chemistry of mine water of the "Rydułtowy" coal mine. In this case the graphical interpretation of biplot revealed large relative variation between HCO3 –-Cl–, HCO3–-I – and HCO3–-Na+. Besides, on the same basis, possible independence between the ion couples: HCO3--Br–, Ca2+-Na+, HCO3–-Cl–, Br-Na+, HCO3–-Cl–and Ca2+-K+ was identified and consequently verified using statistical tests. Additionally, taking into account geometrical features of the relevant biplot, a formula was proposed for defining relationships between shares of ions: Ca2+, Mg2+, Na+ and Cl–<.sup>, SO42–, HCO>sub>3–. These relationships are most apparent for poly-ion groundwater of the active exchange zone, where the ratios of the above mentioned components are similar to each other, despite a slight predominance of SO42– and HCO3– fractions.

3

Rock porosity determination in the historical monuments preservation

Labus M.

Civil and Environmental Engineering Reports

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2009

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No. 3

103-113

EN

Since ancient times people have used natural stone materials for building purposes. The need of safeguarding historical sites and cultural heritage provoke considering the precise technical characterization of building stones and their changes in weathering processes. In the paper there were listed detailed petrographical analysis used for assessing the quality and durability of the stone material. The porosity properties are detected by means of a range of methods, divided into two groups: direct (including thin section microscopy and scanning electron microscopy), which allow direct documentation and measuring of pore space; and indirect (including mercury porosimetry or nitrogen sorption method), which enable calculating the porosity data from the measuring results. Precise knowledge of porosity characteristics, like total porosity, pore sizes, pore size distribution and pore surface is essential for: stone characterization, modeling of transportation processes, assessment of stone durability, interpretation and prediction of the weathering behavior of natural stones, quantification and rating of stone deterioration and evaluation of effectiveness of stone treatments. Basing on the literature digest and own experience, some examples of the stone porosity characteristic application was presented. The variety of natural stones used as construction material, the complicated nature of weathering processes and complex porosity properties determine implication of different analytical methods for stone examination. The most popular method is mercury porosimetry, but it is worth to remember that a reliable characterization of porosity properties can be guaranteed by application of different analytical procedures.

4

Zastosowanie analizy danych złożonych (CDA) w geologii

Labus K., Labus M.

Gospodarka Surowcami Mineralnymi

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2006

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T. 22, z. 2

39-52

PL

W artykule przedstawiono podstawowe założenia metody danych złożonych - Compositional Data Analysis. Metoda ta pozwala na statystyczną interpretację danych, w których wartości zmiennych sumują się do pewnej całości. Pokazano przykłady zastosowania metody CDA dla danych hydrogeologicznych oraz petrologicznych - w tym interpretację tych danych i ich wizualizację za pomocą diagramów trójkątnych. Specyfiką metody jest możliwość stosowania szeregu procedur przekształceń, np. amalgamacji danych, perturbacji, uwalniania i centrowania.

EN

The paper presents the principles of Compositional Data Analysis. This statistical method enables interpreting the data, being proportions of some whole. The two examples of implementation of this method were presented, with use of hydrogeological and petrographical data. The visaulisation by means of ternary diagrams is helpful for interpreting the results. The method is particularly featured by the possibility of appllication of a range of helpful manipulations, such as: amalgamation, perturbation, unconstraining and centering of data.

5

Próba oceny metody porometrii helowej do pomiarów laboratoryjnych porowatości skał

Twardowski K., Traple J., Rychlicki S.

Wiertnictwo, Nafta, Gaz

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2004

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R. 21/2

605-611

PL

Praca przedstawia wyniki międzylaboratoryjnego eksperymentu wyznaczania dokładności (poprawności i precyzji) metody pomiarów porowatości skał z wykorzystaniem porometru helowego i w nawiązaniu do aktualnych podstaw metrologii dotyczących teorii niepewności i błędów pomiarów. Badania prowadzone były w różnym czasie w trzech laboratoriach petrofizycznych związanych z górnictwem naftowym. Jako materiał badawczy wykorzystano 20 próbek skalnych o zróżnicowanym współczynniku porowatości, w granicach od około 1 do około 23%. W wyniku analizy powtarzalnych pomiarów określono w szczególności precyzję metody pomiarowej, w warunkach zarówno powtarzalności, jak i odtwarzalności pomiarów, z uwzględnieniem zmienności wewnątrzlaboratoryjnej oraz międzylaboratoryjnej wyników pomiarów.

EN

Results of an interlaboratory experiment ling in determining the accuracy (correctness and precision) of rock porosity measurements with a helium porosimeter are presented in the paper taking into account foundations of metrology, theory of uncertainty and measurement errors. The experiments were carried out in three different petrophysical laboratories related with oil miting in a different span of time. The research material was composed of rock 20 samples of varying porosity coefficient ranking from about 1 to about 23%. In the course of the analysis, the measurement accuracy was assessed in the conditions of repeatability and reproducibility of experiments, taking into account interlaboratory and intralaboratory variability of the results.

6

Analiza własności zbiornikowo-filtracyjnych skał klastycznych kambru i dewonu południowej części bloku górnośląskiego z wykorzystaniem różnych modeli petrograficznych

Glazor A.

Wiertnictwo, Nafta, Gaz

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1999

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R. 16

167-177

PL

W pracy wykonano badania porowatości, przepuszczalności i krzywych ciśnień kapilarnych dla skał zbiornikowych kambru i dewonu południowej części bloku górnośląskiego. Wybrano skały zbiornikowe z utworów dewonu dolnego oraz kambru w formacji z Goczałkowic i z Borzęt. Wykonano badania korelacyjne, testując różne modele przestrzeni porowej i szukając odpowiedniego modelu petrofizycznego dla analizowanych skał. Stwierdzono, że jedynym modelem który poprawnie opisuje dużą różnorodność wykształcenia przestrzeni porowej jest model Katza-Thompsona, dla którego wyznaczono optymalne współczynniki dopasowania. Wydzielono trzy typowe wykształcenia przestrzeni porowej badanych skał.

EN

Porosity, permeability and capilary pressure investigations were done for reservoir Devonian and Cambrian rocks of south part of Upper Silesian block. Reservoir rocks have been found in Lower Devonian and Goczałkowice and Borzęta formations of Cambrian. Correlation investigations make possible to fit the best model of pore space to those rocks. Results obtained with the use of Kozeny-Carman model were not satisfied because of heterogeneity of parameters of investigated rocks. The best results were obtained with the use of Katz-Thompson model of pore space. Three groups of typical parameters of pore space were described.