scholarly journals ANALYSIS OF THE INFLUENCE OF TRANSDUCER FREQUENCY ON THE ULTRASONIC MEASUREMENT OF CONCRETE HOMOGENEITY

2019 ◽  
Vol 22 ◽  
pp. 48-51
Author(s):  
Dalibor Kocáb ◽  
Petr Misák ◽  
Barbora Jindrová ◽  
Martin Alexa ◽  
Tomáš Vymazal
Keyword(s):  
Statistical Analysis ◽  
Transit Time ◽  
Concrete Slab ◽  
Pulse Transit Time ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Ultrasonic Measurement ◽  
Transducer Frequency

The paper analyses the influence of transducer frequency on the determination of concrete homogeneity using the ultrasonic pulse velocity test. Transit time measurements were made on a 590×590mm concrete slab, with 110mm in thickness, in a raster of 5×5 points, which means the slab was tested in 25 places. The tests were made using a Pundit PL-200 ultrasonic tester using transducers set at 54, 82, and 150 kHz. Two types of measurements were performed – spot measurements of the ultrasonic pulse transit time at each point and full area scanning. The paper is concluded by an evaluation of the concrete slab’s homogeneity measured by different transducers and techniques in addition to a statistical analysis of how the results are affected by the transducer frequency.

Examining the Influence of the Shape, Size, and Type of Test Specimens on the Value of Young's Modulus in Lightweight Concrete

2019 ◽  
Vol 292 ◽  
pp. 29-33
Author(s):  
Dalibor Kocáb ◽  
Petr Daněk ◽  
Petr Žítt ◽  
Aleš Tichý ◽  
Martin Alexa
Keyword(s):  
Elastic Modulus ◽  
Statistical Analysis ◽  
Young’S Modulus ◽  
Dynamic Modulus ◽  
Lightweight Concrete ◽  
Young's Modulus ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity

The paper discusses the results of an experiment that focused on measuring Young's modulus in compression using several different specimens. They were made from lightweight concrete with porous aggregate and differed in shape (cylinder × prism), type (casting × core drilling), and size. Each type category counted a minimum of 6 specimens. The determination of Young's modulus was supplemented by a measurement of the dynamic modulus of elasticity determined by the ultrasonic pulse velocity test. The experiment was concluded by a statistical analysis of the measured values, which focused on the influence of each specimen variety on the value of the elastic modulus.

Possibilities of Experimental Determinations of the Modulus of Elasticity in the early Stage of Ageing of Cement Composites

2018 ◽  
Vol 276 ◽  
pp. 35-40
Author(s):  
Romana Halamová ◽  
Dalibor Kocáb ◽  
Barbara Kucharczyková ◽  
Petr Daněk ◽  
Petr Misák
Keyword(s):  
Modulus Of Elasticity ◽  
Early Stage ◽  
Resonance Method ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Load Test ◽  
Cement Composites ◽  
Static Load Test

This paper deals with the possibilities of experimental determination of the dynamic and static modulus of elasticity of fine-grained cement composites in the early stage of setting and hardening - up to 72 hours. Several cement pastes and cement mortars were produced for the purpose of this experiment. The measurement of the modulus of elasticity on the manufactured cement-based composites was carried out in the first 24 hours, each time only by the ultrasonic pulse velocity test using the innovative Vikasonic instrument. In the following 48 hours, the resonance method and the static load test were employed. The results of the pilot measurement and particularly the assessment of the possibilities of determination of the moduli of elasticity are presented in this paper.

Comparison of Ultrasonic Methods for Thermally Damaged Concrete Nondestructive Testing

2018 ◽  
Vol 776 ◽  
pp. 86-91
Author(s):  
Michal Matysík ◽  
Ladislav Carbol ◽  
Zdenek Chobola ◽  
Richard Dvořák ◽  
Iveta Plšková
Keyword(s):  
Nondestructive Testing ◽  
Elastic Wave ◽  
Measurement Technique ◽  
Ultrasonic Pulse Velocity ◽  
Ultrasonic Pulse ◽  
Pulse Velocity ◽  
Ultrasonic Measurement ◽  
Ultrasonic Methods ◽  
Nonlinear Elastic ◽  
Nonlinear Elastic Wave

Behaviour of concrete under elevated temperatures is very complex. There is a change of mechanical and physical parameters with temperature. In this paper we study the relations of thermal damage processes in concrete and parameters obtained by different ultrasonic methods. The concrete specimens were heated in programmable laboratory furnace. Selected temperature (200°C, 400°C, 600°C, 800°C, 1000°C and 1200°C) were maintained for 60 minutes. The first ultrasonic measurement technique in this paper was Ultrasonic Pulse Velocity method. The pulse velocity in a concrete depends on its density and its elastic properties. Therefore, it is possible to deduce the quality and the compressive strength of the concrete from the ultrasonic pulse velocity. The second ultrasonic measurement technique in this paper uses broadband pulse-compression signal, with variable amplitude to measure the change of fundamental frequency. This method is based on Nonlinear Elastic Wave Spectroscopy. Nonlinear Elastic Wave Spectroscopy methods takes advantage of the fact, that nonlinearities in material manifest themselves as a resonant frequency shifts and harmonics or dumping coefficients changes. The progress of nondestructive testing parameters was confirmed by results from the destructive tests.

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