Browsing Ústav fyziky by Title
Now showing items 1-20 of 55
-
The Acoustic Emission Parameters Obtained during Three-point Bending Test on Thermal-stressed Concrete Specimens
(Elsevier, 2017-06-02)Fire response of concrete structural members depends on thermal, mechanical, and deformation properties of concrete. These properties vary significantly with temperature and also depend on the composition and characteristics ... -
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 ... -
Advanced Evaluation of the Freeze–Thaw Damage of Concrete Based on the Fracture Tests
(MDPI, 2021-10-25)This paper presents the results of an experimental program aimed at the assessment of the freeze–thaw (F–T) resistance of concrete based on the evaluation of fracture tests accompanied by acoustic emission measurements. ... -
Analysis of Acoustic Emission Signals Recorded during Freeze-Thaw Cycling of Concrete
(MDPI, 2021-03-05)This manuscript deals with a complex analysis of acoustic emission signals that were recorded during freeze-thaw cycles in test specimens produced from air-entrained concrete. An assessment of the resistance of concrete ... -
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 ... -
The Application of Acoustic Emission Technique to Monitor the Early Setting Process of Cement Pastes
(EDP Sciences, 2019-12-12)The obtained physico-mechanical properties (mainly flexural and compressive strength) of cement-based composite materials depend on various factors (type of mixture, its composition, standard hardening process, proper ... -
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 ... -
Blastfurnace Hybrid Cement with Waste Water Glass Activator: Alkali-Silica Reaction Study
(MDPI, 2020-08-17)Hybrid systems represent a new sustainable type of cement combining the properties of ordinary Portland cement and alkali-activated materials. In this study, a hybrid system based on blast furnace slag and Portland clinker ... -
Carbon admixtures influence on the electrical properties of slag mortars focusing on alternating conductivity and permittivity
(Elsevier, 2016-08-01)New materials based on alkali-activated slag mortars may be an important contribution of applied research, which strives to offer the use of waste materials as a full replacement for the currently used binders and explores ... -
Change in the Sensory Properties of Alkali Activated Slag Mortars
(Elsevier, 2020-01-27)This article describes how the test slag mortars with addition of carbon powder COND 986 by electrical impedance spectroscopy measurement methods and their extensions in the form of using ZNC vector network analyzer with ... -
Comparison of results of impedance spectroscopy methods with results of impact-echo method in investigation of high-temperaturedegraded concrete
(Elsevier, 2016-08-01)The growth in the transport industry results in more accidents, which often include fire in locations with the concrete structures, which also effects its lifetime and its functionality. After any case of fire loading it ... -
Comprehensive Testing Techniques for the Measurement of Shrinkage and Structural Changes of Fine-Grained Cement-Based Composites during Ageing
(Hindawi Publishing Corporation, 2017-01-15)The paper deals with an experimental analysis focusing on the utilization of a specific measurement technique for determining the development of shrinkage and for monitoring structural changes in fine-grained cement-based ... -
Computer Evaluation of Asperity Topology of Rock Joints
(Elsevier, 2015-09-07)Grounds beneath large civil engineering structures (bridges, dams, tunnels) that are established in the terrain of rock discontinuities represent a risk of mechanical failure. The surface topology of joint surfaces strongly ... -
Convective heat transfer inside planar solar collectors
(IOP Publishing, 2020-12-09)There is a permanent interest in improving the construction and thermal properties of the planar solar collectors. Minimizing the heat losses of the collectors and improving their energy gains are some of the relevant ... -
Decalcification resistance of various alkaliactivated materials
(IOP Publishing, 2021-09-29)The resistance of alkali-activated materials (AAMs) to degradation processes, particularly the decalcification, was studied in this paper. The ground granulated blast furnace slag was alkali-activated using various activators ... -
Efect of Chemical Aggressive Media on the Flexural Properties of Cured-In-Place Pipes Supported by Microstructure Observation and Acoustic Emission
(MDPI, 2020-07-08)The cured-in-place pipe (CIPP) method is currently the most frequently used approach for the renovation of piping without digging; this technology is suitable for pipes made from all types of material. The authors of this ... -
Effect of Hammer Type on Generated Mechanical Signals in Impact-Echo Testing
(MDPI, 2021-01-28)The impact-echo diagnostic method is a well-known nondestructive pulse compression test method, which can be relatively easily used for the testing of concrete and reinforced concrete elements. The evaluation of the ... -
Effect of Metallic Inclusions on the Compressive Strength of Cement-Based Materials
(Hindawi, 2018-12-26)In the concrete foundations, materials come into contact with bedrocks. The surfaces of bedrocks are often covered by sharp protrusions called asperities. Although geotechnical engineers have developed a reliable theory ... -
Effect of steel fibres dosage in alkali-activated slag mortars on acoustic emission obtained during three-point bending tests
(EDP Sciences – Web of Conferences, 2017-05-24)The acoustic emission phenomenon is directly associated with nucleation of cracks in structural materials during loading. This paper analyses acoustic emission signals captured during three-point bending fracture tests of ... -
Electric conductivity changes in geopolymer samples with added carbon nanotubes
(Elsevier, 2016-08-01)By incorporation of nanotubes to the current composite materials, their properties can be significantly improved. Carbon nanotubes can act as filler, which minimizes the air gaps content in the matrix. The denser structure ...