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  • 1.
    Duarte, Margarida Taborda
    et al.
    Luleå tekniska universitet.
    Lindqvist, Per-Arne
    Kou, S.Q.
    Luleå tekniska universitet.
    Miskovsky, Karel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Quantitative characterization of rock material for modelling of microstructure2003In: Konferens i mineralteknik / [ed] Marianne Thomaeus; Eric Forssberg, Föreningen Mineralteknisk Forskning / Swedish Mineral Processing Research Association , 2003Conference paper (Other academic)
  • 2.
    Duarte, Margarida Taborda
    et al.
    Geomaterials Research, Cnh da Figueira.
    Liu, H.Y.
    Luleå tekniska universitet.
    Kou, S.Q.
    Luleå tekniska universitet.
    Lindqvist, Per-Arne
    Miskovsky, Karel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Microstructural modeling approach applied to rock material2005In: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024, Vol. 14, no 1, p. 104-111Article in journal (Refereed)
    Abstract [en]

    The importance of the microstructural parameters in rock mechanical behavior has been investigated by several authors. Moreover, the Weibull statistical model has been used to characterize the heterogeneity of several materials on the basis of the concept that the microscopic defects within the material determine their mechanical strength. The modeling of different rocks is a topic that is fundamental for the prediction of rock fragmentation. In this article, the analysis of rock microstructure is performed using the microstructural modeling approach, which consists of the simplification, quantification, and modeling of the main properties of rock microstructure. The grain size, grain shape, and microcracks are modeled by means of statistical density functions, namely, Cauchy, chi-squared, exponential, extreme value, gamma, Laplace, normal, uniform, and Weibull. It is found that the Weibull distribution is the most appropriate statistical model of the grain size and grain shape, when compared with the other eight statistical models. Regarding microcracks, the results show that the gamma distribution is the most appropriate model. The Weibull and gamma distributions are then used to analyze the heterogeneity of the microstructure. This is done by comparison of the statistical models of each microstructural property evaluated in several thin sections of the same rock. It is found that with respect to grain size and grain shape, the rock is homogeneous, while the size distribution of the microcracks shows a clear trend toward less homogeneity. The microstructural modeling approach is important for modeling, characterizing, and analyzing the microstructure of rock material. Among other applications, it can be used to explain differences in the mechanical behavior obtained in testing several specimens.

  • 3.
    Jacks, Gunnar
    et al.
    Kungliga tekniska högskolan, KTH.
    Lövgren, Lars
    Umeå universitet.
    Löfgren, Ola
    Miskovsky, Karel
    Study of the chemical and ecological status of Lake Hornträsket, mining district of Kristineberg, Northern Sweden2005In: Securing the future: international conference on mining and the environment, metals and energy recovery : proceedings, Stockholm: SweMin , 2005, p. 467-476Conference paper (Other academic)
  • 4.
    Johansson, Eva
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Loorents, Karl-Johan
    VTI - Statens väg-och transportforskningsinstitut.
    Miskovsky, Karel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    A method for estimation of free mica particles in aggregate fine fraction by image analysis of grain mounts2007Conference paper (Other academic)
  • 5.
    Johansson, Eva
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Miskovsky, Karel
    Project: Estimation of rock aggregate quality in the road alignment by using drill cuttings analysis - by using drill cuttings analysis2010Other (Other (popular science, discussion, etc.))
    Abstract [en]

    The drill cuttings method is used for qualitative evaluation of rock aggregate in the road alignment during the road project stage

  • 6.
    Johansson, Eva
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Miskovsky, Karel
    Loorents, Karl-Johan
    Swedish Road Administration.
    Estimation of rock aggregates quality using analyses of drill cuttings2009In: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024, Vol. 18, no 3, p. 299-304Article in journal (Refereed)
    Abstract [en]

    There is a need for an effective method to estimate the quality of crushed rock aggregates and its usability in the early stages of project planning, e.g., for road and railway constructions and quarry prospecting. The proposed method is based on mineralogical and petrographic analyses of drill cuttings and analysis of the coarse fraction to estimate the homogeneity/heterogeneity of the bedrock. The geological analyses are followed by an estimation of the rock materials' mechanical properties and their potential technical usability. Development and practical applicability (field and laboratory) of the method have been performed and correlated to three road projects from regions of different geological and climatic zones in Sweden. The study confirms the capability of the proposed method as a surveying tool.

  • 7.
    Johansson, Eva
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Miskovsky, Karel
    Loorents, Karl-Johan
    VTI - Statens väg-och transportforskningsinstitut.
    Löfgren, Ola
    Ekovision nord, Vindeln.
    A method for estimation of free mica particles in aggregate fine fraction by image analysis of grain mounts2008In: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024, Vol. 17, no 2, p. 250-253Article in journal (Refereed)
    Abstract [en]

    The need to evaluate free mica grains in fine fraction of aggregate products has initiated the development of a statistically and scientifically acceptable method. The proposed method is based on a modified point-counting approach using digital micro photos of thin sections of aggregate grains and a software package to sustain sample analysis. A thin section of aggregate grains provides permanent sample documentation readily available for complimentary or other analysis. Statistical analysis, together with a repeatable analysis of samples (permanent mounts), confirms the robustness of the method. The method is appropriate as a complementary assessment tool to estimate and trace changes or variations in quality of rock aggregate. Though, the estimation of free mica particles in fine fraction needs to be combined with other analyses, e.g., petrographic analysis and analyses of mechanical properties, to assess the quality of any rock material. As the samples can be collected from drill cuttings, i.e., an accessible residual product obtainable from surveying or production, the present method is particularly useful as a surveying tool and in prospecting and projecting activities.

  • 8.
    Johansson, Per
    et al.
    LTU.
    Miskovsky, Karel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Bergmaterialens betydelse för vägens underhållskostnad2003Report (Other academic)
    Abstract [sv]

    Projektets mål var att utreda i vilket mån bergmaterialkvaliteten påverkar kostnader för vägunderhåll. Till detta ändamål valdes två vägsträckor med jämförbar vägkonstruktion, ÅDT och tidpunkt för rekonstruktion men med olikheter när det gäller använt bergmaterial. De utvalda sträckorna väg nr 620 Vindeln-Botsmark och nr 1077 Dikanäs- Västansjö studerades med hänsyn till undergrund, konstruktionens bergmaterial samt bygg- och underhållskostnader. Underlagsmaterial erhölls dels från vägverkets arkiv, entreprenörernas dokumentation dels genom egna provtagningar och analyser. Bergmaterialet studerades med avseende på kornfördelning, mekaniska egenskaper och petrografiska egenskaper. Undersökningens resultat indikerar starkt att bergmaterialkvaliteten har stort inflytande på underhållskostnader. Medan underhållskostnader för väg 620 Vindeln-Botsmark med bergmaterial bestående av glimmerskiffrar och glimmerrika gnejser (metagråvackor) var i hundratusen till femhundratusenklassen per kilometer var underhållskostnader noll under samma period hos väg 1077, Dikanäs-Västansjö, byggd av kvartsit och skiffrig sericit-klorit kvartsit. I regioner med brist på kvalitetsmaterial föreslås att bergmaterialkvaliteten införs som mjuk parameter vid upphandlingar. Vidare föreslås införande av regionalt anpassade kvalitetskrav på bergmaterial och skärpning av kraven på förundersökningar i planeringsstadiet, särskilt när det gäller användning av bergmaterial från bergskärningar längs vägsträckan. Även testmetodernas relevans med hänsyn till bergmaterialets användning och skärpning av kontrollen av återvinningsmaterial bör ses över.

  • 9. Kondelchuk, Dimitri
    et al.
    Miskovsky, Karel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Determination of the test methods sensitive to free mica content in aggregate fine fractions2009In: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024, Vol. 18, no 3, p. 282-286Article in journal (Refereed)
    Abstract [en]

    The detrimental influence of mica rich aggregates on structural deterioration of road pavement has been discussed in the literature for over a half century. This negative effect is of great importance especially for regions with crystalline, mica-rich bedrock and temperate, subarctic climates. Recent investigations reveal that elevated fractions of free mica particles in unbound granular materials, used in road constructions, greatly reduce bearing capacity and influence the hydraulic behavior of the road structure. Despite the awareness of mica's potential harmful effect, the absence of properly adapted analytical methods is noticeable. The scope of the current study was to test two possible analytical methods which, are susceptible to mica content and could be used as an indicating technique for quantitative determination of free mica particles in unbound granular materials. Two standard methods: Sand equivalent test and methylene blue (MB) test were assumed as the most sensitive to mica presence. The rock samples used in the tests are representative for the common crushed rock aggregates for construction purposes with different contents of mica. Both methods showed susceptibility to mica content and gave strong correlation in terms of mica content. The result of the MB test can be explained by the schistose structure of mica particles and the ability of mica to absorb liquids. Another important explanation is the increased reaction surface of mica particles, which leads to an increase in the total reaction surface of the sample. The receptiveness of the sand equivalent test to mica content could be caused by the ability of mica to stay in suspension due to its flake-shaped grains.

  • 10.
    Miskovsky, Karel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Enrichment of fine mica originating from rock aggregate production and its influence on the mechanical properties of bituminose mixtures2007Conference paper (Other academic)
  • 11.
    Miskovsky, Karel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Enrichment of fine mica originating from rock aggregate production and its influence on the mechanical properties of bituminous mixtures2004In: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024, Vol. 13, no 5, p. 607-611Article in journal (Refereed)
    Abstract [en]

    Analyses of mica-bearing, crushed granitoid rocks revealed a significant enrichment of free mica in the fine fraction. Qualitative tests of bituminous mixtures with an increasing content of free mica in the fine fraction suggested a considerable deterioration of the mechanical properties of the asphalt mass. The negative influence of fine mica on the mechanical properties of the asphalt mixtures was most likely caused by the ability of mica to adsorb bitumen and to create zones of weakness. This phenomenon seemed to be linked to a preferred orientation (foliation) of the mica particles that was connected to the compaction of asphalt masses during the construction of the surface course. The threshold content at which the fine mica negatively influenced the quality of the bituminous mixtures was estimated to be 30-35 vol.%.

  • 12.
    Miskovsky, Karel
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Duarte, M. Taborda
    Luleå tekniska universitet.
    Kou, Shaoquan
    Luleå University of Technology.
    Lindqvist, Per-Arne
    Influence of the mineralogical composition and textural properties on the quality of coarse aggregates2004In: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024, Vol. 13, no 2, p. 144-150Article in journal (Refereed)
    Abstract [en]

    To evaluate the influence of the petrographic variables on the quality of coarse aggregates consisting of granitoid (granite to tonalite) rocks, 17 samples selected from the Swedish part of the Baltic shield have been studied concerning their petrographic properties, for example, mineral composition, grain size, grain boundaries, and the frequency of micro-cracks. All of the samples selected also have been studied in mechanical tests used to evaluate the quality of aggregates in Sweden. The quality has been determined by means of flakiness, impact value, abrasion value I, and abrasion value II. An analysis of the influence of the mineral composition and textural properties on the aggregate quality has been performed using statistical correlation and linear models. The results indicate that an increasing content of feldspar negatively influences the strength against impact, while an increasing content of mica (tested to 35 vol.%) combined with a diminishing grain size and more irregular grain boundaries has a positive influence on the resistance of granitoids to mechanical impact. Abrasion value II seems to be mainly influenced negatively by an increasing frequency of micro-cracks. The practical implementation of the results is suggested.

  • 13.
    Miskovsky, Karel
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Duarte, Margrida Taborda
    Kou, S.Q
    Luleå tekniska universitet.
    Lindqvist, Per-Arne
    Influence of the mineralogical composition and textural properties on the quality of coarse aggregates2007In: 2007 General Assembly of the European Geosciences Union, Vienna (Austria), 15-20 Apr 2007, European Geosciences Union (EGU), 2007Conference paper (Other academic)
  • 14. Miskovsky, Karel
    et al.
    Loorents, Karl-Johan
    Projektdeltagare, VT, Sverige.
    Project: Testing and calibration of LA-testing method for aggregates2010Other (Other (popular science, discussion, etc.))
    Abstract [en]

    Testing of selected, critical rocks samples concerning their mechanical properties for calibration of LA-method as an EU standard for testing of rock fragmentation.

  • 15.
    Miskovsky, Karel
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Prikryl, Richard
    Charles University of Prague, Faculty of Science, Institute of Geochemistry, Mineralogy and Mineral Resources.
    Loorents, Karl-Johan
    VTI - Statens väg-och transportforskningsinstitut.
    Göransson, M.
    Geological Survey of Sweden.
    Establishment of data base for mechanical characteristics of the common rock materials used for aggregate construction2006Conference paper (Other academic)
  • 16.
    Miskovsky, Karel
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Prikryl, Richard
    Charles University of Prague, Faculty of Science, Institute of Geochemistry, Mineralogy and Mineral Resources.
    Loorents, Karl-Johan
    VTI - Statens väg-och transportforskningsinstitut.
    Göransson, M.
    Geological Survey of Sweden.
    Török, A.
    Budapest University of Technology and Economics, Department of Construction Materials and Engineering Geology.
    Establishment of database for mechanical characteristics of the common rock materials used for aggregate production2007Conference paper (Other academic)
  • 17. Novikov, Evgeny
    et al.
    Miskovsky, Karel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    The capillarity of mica-rich base-course aggregates2009In: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024, Vol. 18, no 4, p. 420-423Article in journal (Refereed)
    Abstract [en]

    In regions of temperate climate, the destructive influence of frost is the main contributor to damage of a road structure. Commonly, the frost susceptibility of base-course aggregates is often ignored in road construction. However, a number of studies on aggregates for construction purposes, and field observations of road failures, indicate a negative influence of mica-rich rock aggregates (used in unbound applications) on the service life of road construction. The scope of the current work investigates the capillary properties of unbound base-course aggregates with varying free mica grains. The materials studied in this research are commercially available road construction aggregates, and originate from different regions of Sweden. The mineral composition of the samples has been determined by polarizing microscopy using a point-count method. The parameter characterizing the capillarity was measured using the test for determining capillary rise (VVMB24). The results show that there is a direct correlation between mica content of the aggregates and water suction by capillary forces. Therefore, mica-rich materials susceptible to frost heave, thus confirming the tendency for frost damage of unbound aggregates.

  • 18.
    Saiang, Christine
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Miskovsky, Karel
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering.
    Effects of heat on the mechanical properties of selected rock types: A laboratory study2011In: Harmonising Rock Engineering and the Environment: proceedings of the 12th ISRM International Congress on Rock Mechanics, Beijing, October 18 - 21, 2011 / [ed] Qihu Qian; Yingxin Zhou, Leiden: CRC Press/Balkema , 2011, p. 815-820Conference paper (Refereed)
    Abstract [en]

    A laboratory study was conducted to study the effect of heat on the mechanical properties of diabase, granite and quartzitic schist at temperatures of 400◦C, 750◦C and 1100◦C. Unheated samples were also studied. The reasoning behind this study was to understand the effect of elevated temperatures on the rock mass, such as in the event of a fire in a rock tunnel. Samples from the aforementioned rock types were heat treated at temperatures shown above, cooled slowly to room temperature and then subjected to uniaxial compression and Brazilian tests. Thin sections were extracted from the heat treated samples for microscopic analyses, which assisted in explaining the reasons for the mechanical behaviour observed from the mechanical test results. The uniaxial compression test showed that the strength of the rock specimens increased by 6% for granite to 29% for diabase at 400◦C when compared to the UCS values of the unheated specimens. From 750◦C to 1100◦C the decay in the strength was very rapid. From the microscopic analyses it was concluded that the increase in the strength of the rock specimens at 400◦C is attributed to the initial reaction of the rock forming minerals, hence the rock specimens were less brittle but more plastic. The rapid drop in the strength from 750◦C to 1100◦C is attributed to the mineralogical changes, micro-cracking and dehydration due to the loss of crystal bound water. At 1100◦C the rocks were highly friable and crumbled very easily when tested mechanically. The effect of mineralogical changes was obvious in diabase where the physical appearance of the samples mimicked that of natural iron, which is believed to be due to the alteration of pyroxene. The result was an increase in strength by 29% at 400◦C compared to the unheated specimens. Even at 750◦C the strength was slightly higher than unheated specimens. In summary; the mechanical behaviour of the rock specimens depended on the temperature level and the mineralogical and physical changes that occur at that temperature.

1 - 18 of 18
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