Now showing items 15-34 of 34

  • Fitting Function for Flexural Strength of Cement Paste 

    Ficker, Tomáš (IOPPublishing, 2017-11-28)
    There are many analytical expressions for compressive strength as functions of porosity of cement-based materials but only a few such expressions exist for flexural strength of these materials. In the present paper a new ...
  • Flexure response of thermal loaded concrete specimens by acoustic emission method 

    Pazdera, Luboš; Topolář, Libor; Mikulášek, Karel; Smutný, Jaroslav; Hoduláková, Michaela; Chobola, Zdeněk; Seelmann, Herbert (EDP Sciences – Web of Conferences, 2017-05-24)
    The response to fire of concrete structural members depends on the thermal, mechanical, and deformation properties of concrete. These properties vary significantly with temperature depending on the composition and ...
  • Fractal Analysis of Rock Joint Profiles 

    Audy, Ondřej; Ficker, Tomáš (IOP Publishing, 2017-11-28)
    Surface reliefs of rock joints are analyzed in geotechnics when shear strength of rocky slopes is estimated. The rock joint profiles actually are self-affine fractal curves and computations of their fractal dimensions ...
  • Fracture properties of concrete specimens made from alkali activated binders. 

    Šimonová, Hana; Kucharczyková, Barbara; Topolář, Libor; Bílek, Vlastimil; Keršner, Zbyněk (IOP Publishing, 2017-09-15)
    The aim of this paper is to quantify crack initiation and other fracture properties – effective fracture toughness and specific fracture energy – of two types of concrete with an alkali activated binder. The beam specimens ...
  • Fracture response of alkali-activated slag mortars reinforced by carbon fibres 

    Šimonová, Hana; Topolář, Libor; Schmid, Pavel; Keršner, Zbyněk; Rovnaník, Pavel (IOP Publishing, 2018-07-12)
    The paper reports a study of the effect of carbon fibres on the mechanical fracture parameters of alkali-activated slag mortars. The carbon fibres were added in the amount of 1, 2 and 3%, respectively with respect to the ...
  • Impact of graphite admixture on electrical properties of alkali-activated slag mortars 

    Kusák, Ivo; Luňák, Miroslav; Rovnaník, Pavel (EDP Sciences, 2017-05-24)
    One of the objectives of the applied research's striving consists in providing the users with new slag-mortar-based materials. Basic research, in its turn, aims at examining the newly created materials from the viewpoint ...
  • Large Rock Reliefs and Their 3D Reconstructions 

    Audy, Ondřej; Ficker, Tomáš (IOP Publishing, 2017-11-28)
    Rock reliefs are used for assessing joint rock coefficients that serve in geotechnical engineering for computing shear strength of rock joints. The three-dimensional reliefs of small rock joints amounting to several ...
  • Low-frequency noise measurements used for quality assessment of GaSb based laser diodes prepared by molecular beam epitaxy 

    Chobola, Zdeněk; Luňák, Miroslav; Vaněk, Jiří; Hulicius, Eduard; Kusák, Ivo (Faculty of Electrical Engineering and Information Technology of the Slovak University of Technology, 2015-08-01)
    The paper reports on a non-destructive method of reliability prediction for semiconductor lasers diodes GaSb based VCSE. Transport and noise characteristic of forward biased were measured in order to evaluate the new MBE ...
  • Macrodefects and Microdefects within Porous Cement Pastes 

    Ficker, Tomáš (IOP Publishing, 2017-11-28)
    It is shown that the mechanical strength of cement matrix (hydrated cement paste) is a result of competitive interplay between macrodefects and microdefects. The dominance of one of these two kinds of defects depends not ...
  • Monitoring of concrete hydration by electrical measurement methods 

    Kusák, Ivo; Luňák, Miroslav; Chobola, Zdeněk (Elsevier, 2016-08-01)
    Analysis of impedance spectra of inhomogeneous materials is a part of the impedance spectroscopy which is still waiting for its development. Materials having higher electric resistance values (over 500 kohm) can be considered ...
  • NDT of Mechanical Damaged Concrete Specimens by Nonlinear Acoustic Spectroscopy Method 

    Matysík, Michal; Plšková, Iveta; Kořenská, Marta; Kucharczyková, Barbara (Ministry of Transport, 2010-04-14)
    Current research and development of non-linear ultrasonic spectroscopy methods shows these methods to be very promising for material testing and defectoscopy in the near future. Our experiments focused on the testing of ...
  • Nondestructive Testing of Advanced Concrete Structure during Lifetime 

    Pazdera, Luboš; Topolář, Libor; Smutný, Jaroslav; Timčaková, Kristýna (Hindawi Publishing Corporation, 2015-07-08)
    The paper reports on measurements and analysis of the measurements during hardening and drying of specimens using selected acoustic nondestructive testing techniques. An integrated approach was created for better understanding ...
  • Nonlinear Elastic Wave Spectroscopy with MLS Perturbation Signal 

    Carbol, Ladislav; Martinek, Jan; Kusák, Ivo; Kucharczyková, Barbara (Výzkumný ústav stavebních hmot,a.s., 2016-05-31)
    The article describes a test procedure based on the fundamental principle of Nonlinear Elastic Wave Spectroscopy. Without integration of all test stages into one automated measurement station and without Maximum Length ...
  • On the effect of addition of carbon nanotubes on the electric conductivity of alkali-activated slag mortars 

    Kusák, Ivo; Luňák, Miroslav (IOP Publishing, 2017-10-18)
    This paper presents basic electric properties of laboratory prepared alkali-activated composite materials on the basis of finely ground granular high furnace slag to which various quantities of carbon nanotubes (CNT) have ...
  • Properties of concrete intended for further testing measured by the Impact-Echo and the ultrasonic pulse method 

    Karel, Ondřej; Dvořák, Richard; Rozsypalová, Iva; Schmid, Pavel (IOP Publishing, 2018-07-16)
    The aim of the paper is non-destructive measurement of differently degraded specimens by high temperature intended for further testing of joints of stainless steel helical reinforcement glued into the groove and differently ...
  • Rock Joint Asperities and Mechanical Strength of Concrete 

    Ficker, Tomáš; Komárková, Tereza (IOP Publishing, 2017-11-28)
    Mechanical interactions between concrete foundations of large civil engineering structures (tunnels, bridges or dams) and the asperity surfaces of rock masses represent a useful topic for investigation. It is obvious that ...
  • Rock Joint Coefficients Derived from the Three-Dimensional Fourier Reliefs 

    Audy, Ondřej; Ficker, Tomáš (IOP Publishing, 2017-11-28)
    Coefficients of rock joints serve in geotechnical practice for determining shear strength of rock masses. Evaluation of the stability of rocky terrains containing joints is important from the viewpoint of safety. Larger ...
  • Rupture Strength and Irregularity of Fracture Surfaces 

    Ficker, Tomáš (IOP Publishing, 2017-11-28)
    Textural irregularities of fracture surfaces of cement-based materials seem to be an interesting source of information on some mechanical properties. Besides compressive strength, the flexural strength is strongly correlated ...
  • The use of the acoustic emission method for the monitoring of changes in the internal structure of polymer-cement mortars when testing the static compressive modulus of elasticity 

    Kocáb, Dalibor; Topolář, Libor; Kucharczyková, Barbara; Hoduláková, Michaela; Daněk, Petr (EDP Sciences – Web of Conferences, 2017-05-24)
    The paper focuses on the experimental determination of the dynamic and static compressive modulus of elasticity of selected polymer-cement mortars and their comparison. The dynamic modulus of elasticity was determined by ...
  • Using acoustic emission methods to monitor cement composites during setting and hardening 

    Topolář, Libor; Pazdera, Luboš; Kucharczyková, Barbara; Smutný, Jaroslav; Mikulášek, Karel (MDPI AG, 2017-04-28)
    Cement-based composites belong among the basic building materials used in civil engineering. Their properties are given not only by their composition but also by their behaviour after mixing as well as by the methods of ...