Browsing Ústav fyziky by Issue Date
Now showing items 21-40 of 61
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Experimental Analysis of the Development of Elastic Properties and Strength under Different Ambient Temperature During the Hardening of Concrete
(Elsevier, 2017-07-20)This paper focuses on the experimental assessment of the degree to which continued exposure to low ambient temperatures influences the concrete modulus of elasticity and compressive strength. The elastic modulus is not a ... -
Fracture properties of concrete specimens made from alkali activated binders.
(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 ... -
On the effect of addition of carbon nanotubes on the electric conductivity of alkali-activated slag mortars
(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 ... -
The Assessment of Cement Mortars after Thermal Degradation by Acoustic Non-destructive Methods
(IOP Publishing, 2017-10-25)Thanks, the terrorist attacks on the worldwide interest in the design of structures for fire greatly increased. One of the advantages of concrete over other building materials is its inherent fire-resistive properties. The ... -
Electrical properties of alkali-activated slag composite with combined graphite/CNT filler
(IOP Publishing Ltd., 2017-10-25)Alkali-activated industrial by-products such as blast furnace slag are known to possess properties which are comparable to or even better than those observed for ordinary Portland cement. The combination of alkali-activated ... -
Rock Joint Asperities and Mechanical Strength of Concrete
(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 ... -
Fitting Function for Flexural Strength of Cement Paste
(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 ... -
Rupture Strength and Irregularity of Fracture Surfaces
(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 ... -
Macrodefects and Microdefects within Porous Cement Pastes
(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 ... -
Rock Joint Coefficients Derived from the Three-Dimensional Fourier Reliefs
(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 ... -
Large Rock Reliefs and Their 3D Reconstructions
(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 ... -
Evaluation of Rock Joint Coefficients
(IOP Science, UK, 2017-11-28)A computer method for evaluation of rock joint coefficients is described and several applications are presented. The method is based on two absolute numerical indicators that are formed by means of the Fourier replicas of ... -
Fractal Analysis of Rock Joint Profiles
(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 response of alkali-activated slag mortars reinforced by carbon fibres
(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 ... -
Experimental evaluation of the effect of carbon fibres on acoustic emission parameters obtained during compressive strength tests of alkaliactivated slag composites
(IOP Publishing, 2018-07-12)The generation of acoustic emission signals is directly associated with formation of cracks in materials during loading. This paper deals with possibilities of acoustic emission method application as the tool for the ... -
Analysis of temperature degraded concrete at high temperature by applying of non-linear characteristics
(IOP Publishing, 2018-07-12)Concrete structures are commonly exposed to thermal loads as a result of the structure, ambient conditions, the heat of hydration, or exposure to fire. Therefore, there has been a growing interest in the research of advanced ... -
Properties of concrete intended for further testing measured by the Impact-Echo and the ultrasonic pulse method
(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 ... -
Experimental assessment of steel fibre reinforced concretes with different concentrations of fibres
(IOP Publishing, 2018-07-16)At present, steel fiber reinforced concrete can be classified as a composite material commonly used for load-bearing building structures. Adding steel fibers to fresh mixture improves its mechanical properties in comparison ... -
The experimental comparison of parameters signals of acoustic emission during destructive test on composites based on cement
(MATEC Web of Conferences, 2018-10-29)The paper reports the analysis of acoustic emission signals captured during compressive strength tests of fine-grained cement-based composites of various composition. Acoustic emission monitoring belongs to a non-invasive ... -
Acoustic non-destructive testing of high temperature degraded concrete with comparison of acoustic impedance
(MATEC Web of Conferences, 2018-10-30)The paper is focused on non-destructive measurement of high temperature degraded concrete test specimens of three mixtures different by the use of coarse aggregate. Testing is done by ultrasonicpulse velocitymethod and ...