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    Wyświetlanie 1-2 z 2
    Tytuł:
    Rock porosity determination in the historical monuments preservation
    Autorzy:
    Labus, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/396653.pdf
    Data publikacji:
    2009
    Wydawca:
    Uniwersytet Zielonogórski. Oficyna Wydawnicza
    Tematy:
    porowatość skał
    oznaczanie porowatości skał
    zabezpieczanie pomników
    rock porosity
    determination of rock porosity
    Opis:
    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.
    Źródło:
    Civil and Environmental Engineering Reports; 2009, 3; 103-113
    2080-5187
    2450-8594
    Pojawia się w:
    Civil and Environmental Engineering Reports
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Rock pore structure as main reason of rock deterioration
    Autorzy:
    Ondrášik, M.
    Kopecký, M.
    Powiązania:
    https://bibliotekanauki.pl/articles/178163.pdf
    Data publikacji:
    2014
    Wydawca:
    Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
    Tematy:
    mechanical weathering
    rock deterioration
    adsorbed water
    adsorbed water freezing
    rock porosity
    freeze-thaw loss
    proces zamrażania i rozmrażania
    wietrzenie mechaniczne
    adsorpcja wody
    porowatość skał
    Opis:
    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.
    Źródło:
    Studia Geotechnica et Mechanica; 2014, 36, 1; 79-88
    0137-6365
    2083-831X
    Pojawia się w:
    Studia Geotechnica et Mechanica
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-2 z 2

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