Ultrasonic Pulse Method Research Articles

Effects of NaCl concentration on electrical resistivity of clay with cooling

The influence of salt concentration and gravimetric water content on the freezing process of clay soil is studied by using electrical resistivity as a measurement. Along with the ultrasonic pulse method, the P-wave velocity of samples is obtained to estimate the unfrozen water content of frozen soil, and the development of cracks due to frost heave at different temperatures is also analyzed. The results indicate that the freezing temperatures of samples with a sodium chloride (NaCl) concentration of 0, 2% and 5% are −4 °C, −6 °C and −5 °C respectively. Cracks due to frost heave propagate rapidly at temperatures below the crack coalescence temperature, which results in a steep increase in electrical resistivity. There is a sigmoid function for the relationship between electrical resistivity and temperature. A good power function is found for the relationship between electrical resistivity and the NaCl concentration of clay soil. There is a power function for the relationship between the electrical resistivity of pore water and salinity. The electrical resistivity decreases linearly with water content at temperatures above freezing but increases logarithmically at temperatures below freezing. The generalized relationships between electrical resistivity and water content, NaCl concentration and temperature are effective for predicting the electrical resistivity of frozen saline soil in practice.

Development of Devices for the System of Monitoring the Strength Features of Concrete in Operated Buildings and Structures Based on the Ultrasonic Pulse Method


 Operation of buildings and structures for various purposes is accompanied by an impact on their structural elements, building materials, and a complex of negative factors. These factors include the lifespan, climatic parameters, static and dynamic loads, dustiness, air pollution, etc. Their action worsens the physico-mechanical characteristics, the structure of concrete. This reduces the reliability of structural elements, reduces the life of the construction object. In DBN V. 1.2-14-2009 «The system of ensuring the reliability and safety of construction objects» set the classification of construction objects by classes of consequences in the event of an accident. The estimated lifetimes of each type of construction objects are also determined. Extension of life is allowed only after inspection and evaluation of the technical condition of the construction object, material characteristics, through the determination of the degree of their compliance with regulatory requirements. The importance of obtaining reliable survey results requires the improvement of relevant instruments and metrology. The described developed system of monitoring of construction objects, as well as instrumentation and system based on the ultrasonic pulse method. They are designed to control the physico-mecha-nical characteristics, the structure of concrete and other building materials. The developed devices and system are characterized by increased accuracy, reliability and reliability of measurements.

Nano Particles and Nano Composites for Preservation of Historic Marble Minbars with Application on the Minber of Soliman Pasha Al-Khadim Mosque in Salah El-Din Citadel in Cairo, Egypt

Minbar, in Islam, the pulpit from which the sermon (khutbah) is delivered. In its simplest form, the minbar is a platform with three steps. Often it is constructed as a domed box at the top of a staircase and is reached through a doorway that can be closed. Soliman pasha Al-Khadim mosque in Salah El-Din citadel in Cairo is considered the first mosque with ottoman architectural style. This Minbar exposed to aggressive human intervention by mosque workers and archaeological crafts unity-ministry of antiquities in Egypt, to lose more of its historical and architectural values. Now this Minbar undergoes restoration process, they are removing all modern pigments and remains of last reconstruction in 2014 so we proposed some Nano particles and Nano composites for Preservation of it. The study started with the characteristics of the historic architectural elements of Mibars and their joining structural mortars in order to risk assessment and to define the necessary characteristics of the intervention retrofitting new materials, which will be used in the ongoing preservation work of these stucco architectural elements. To achieve such, several analyses and laboratory tests like ultra-sonic pulse method testing and uniaxial compression test were carried out to determine their basic, physical and mechanical properties, along with the microstructural properties determination using Mercury porosimeter. On the other hand, the morphological description, petrography, mineralogical and microstructural properties were determined using scanning electron microscope equipped by EDS, transmission electron microscopy TEM, polarizing light microscopy, XRD and XRF. The results proved the superiority of the samples that have been strengthened by nano lime concentration of 2% with Wacker OH 100 concentration in 5%.

CHARACTERIZATION OF CEMENT-BASED COMPOSITE EXPOSED TO HIGH TEMPERATURES VIA ULTRASONIC PULSE METHOD

In this paper, the attention is paid to the investigation of the influence of high temperature acting on specimens made from specially designed cement-based composite. The experimental programme was carried out on six sets of beam specimens with the dimensions of 20 × 40 × 200 mm. The specimens were loaded to a pre-set temperature of 100, 200, 400, 600, 800 and 1000 °C and then the temperature was kept for 60 minutes. When the temperature loading had been done, the specimens were left to cool down to the ambient temperature. After that, the ultrasonic pulse method was used to determine the degree of damage of temperature loaded specimens. The measured data obtained by this non-destructive method are in high correlation with values of informative compressive strength of the composite obtained after the temperature loading of specimens.

NON-DESTRUCTIVE TESTING AND X-RAY DIFFRACTION ANALYSIS OF HIGH-TEMPERATURE DEGRADED CONCRETE

In the field of civil engineering a diagnostics acoustic non-destructive testing is widely used and in the past years it was used even in testing of high-temperature degraded concrete structures. These methods can provide specific information about the physical-mechanical state of material; however physical-chemical changes in microstructure are measurable to a limited extent. This article is focused on non-destructive and destructive testing of high-temperature degraded concrete test beams of dimensions 0.1 × 0.1 × 0.4 m fired at 200 − 1200 °C. The Impact-Echo method and ultrasonic velocity pulse method measurements are compared with destructive test results. Testing of measured changes in the p-m properties of reference and fired samples is then supplemented by X-ray diffraction analysis, in order to document mineralogical physical-chemical changes of tested material.

Improvement of Accuracy of Control of Physical‑Mechanical Characteristics of Materials By Ultrasonic Pulse Method Due to Reduction of Measurement Error of Propagation Time of Elastic Waves

Ensuring the reliability of buildings, structures, analysis of their structural elements during reconstruction or major repair includes the task of determining the physical and mechanical characteristics of materials — strength, homogeneity, evaluation of structural heterogeneity, the presence of microcracks, etc. In solving this problem, an ultrasonic pulse method of non-destructive quality control is used. The basis of the method is the dependence of the parameters of ultrasonic oscillations, on these characteristics when they pass through the material. As the main parameter of the information ultrasonic signal, the time of its passage from the radiating to the receiving ultrasonic transducers is used. The amplitude of the information ultrasonic signal to a large extent depends on the structure of the investigated material, its acoustic resistance. At significant violations of the structure of the material there is a significant decrease in the amplitude of the information signal, which causes an increase in the error of measuring the time of its passage, and hence the definition of characteristics, quality of the investigated material.
 The article describes the developed method of increasing the accuracy of measuring the time of passage of the ultrasonic signal from the radiating to the receiving ultrasonic transducers. The essence of the technique is to use the mathematical modeling of the shape of the ultrasound signal, in particular the form of its so-called «first introduction».

Properties of concrete intended for further testing measured by the Impact-Echo and the ultrasonic pulse method

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 degraded concrete. Measurement intended for determination of possibilities of estimation of future properties of named joints is performed by the Impact-Echo method and by the ultrasonic pulse velocity method on specimens of dimensions 400 × 100 × 100 mm made of concrete of the C20/25 strength class degraded by different elevated temperature. Five sets of specimens were manufactured - four sets of specimens were heated in the furnace at temperatures of 400 °C, 600 °C, 800 °C and 1000 °C and one set was kept intact as reference. Specimens will be afterwards additionally strengthened at the tensile side of specimens and broken by four-point flexural strength test. The non-destructive measurement aims to evaluate the residual physical-mechanical properties of plain concrete in terms of resonance frequency of test specimen, and sound velocity in tested specimen before and after the temperature degradation. This assessment will serve as material information basis for interpretation of the expected behaviour of used helical reinforcement for a retrofitting process and the thermally damaged concrete reaction to such intervention.

Research of frequency and amplitude-frequency characteristics of industrial ultrasound transducers for non-destructive quality control of materials

Ultrasonic pulse method is one of the effective methods of nondestructive quality control of materials. It is used to study a wide range of materials, when inspecting buildings and structures. Its use makes it possible to determine the physical and mechanical characteristics, the structure of materials, the presence of foreign inclusions. When this method is used to study the materials of the porous structure, and also when measuring the characteristics of the ultrasonic signal at considerable distances between the radiating and receiving ultrasonic transducers, a significant attenuation of the amplitude of the information signal is observed. In this case, its amplitude is often at the noise level. This can cause a decrease in the accuracy of the results. One of the directions of providing the necessary levels of accuracy, reliability of the measurement data is the use of the frequency characteristics of the receiving and transmitting path of the monitoring and measuring devices. One of the elements of this path is ultrasonic transducers. The article presents research of frequency and amplitude-frequency industrial ultrasonic transducers made of lead zirconate titanate with specified nominal frequencies of 60, 100 and 150 kHz. Based on the analysis of the research results, conclusions were drawn and recommendations developed aimed at solving the problem of increasing the accuracy, reliability and validity of the measurement results. The solution of this problem will ensure an increase in the accuracy of the control of the quality characteristics of the materials under study ‒ their structure, physical and mechanical characteristics. This research can be used to improve the control and measuring equipment by which this method of non-destructive control is realized.

<i>In Situ</i> Determination of the Elastic Modulus of Concrete by Means of Ultrasonic Pulse Method

The paper deals with the in-situ determination of the modulus of elasticity on the bridge elements using ultrasonic pulse method. This non-destructive test method was chosen for the measurement because of its undisputed advantages that allow the measurement of relatively thick layers of material. For the purpose of the elastic modulus verification the direct measurement was used, in which a pair of transducers (transmitter and receiver) were placed directly opposite to each other. The results of performed in-situ measurements as well as the results of verification tests performed in the laboratory are presented in the paper. The article also discusses the issue of evaluation and interpretation of the results obtained by in-situ measurements using non-destructive test method.

Experimental Analysis of the Development of Compressive Strength, Modulus of Elasticity and Acoustic Emission Parameters of Alkali-Activated Composites

This paper describes an experiment focused on monitoring the development of the modulus of elasticity and the compressive strength of composites that are based on alkali‑activated slag (AAS) during the first 28 days of ageing. The test specimens were tested at the age of 3 and 28 days using two non-destructive methods (ultrasonic pulse and resonance methods) to determine the value of the dynamic modulus of elasticity. Subsequently, the same specimens were used to determine the static modulus of elasticity using compressive stress test, during which the behaviour of the composite was monitored by equipment for recording the acoustic emission in the material. The result of the experiment is the evaluation of the behaviour of the AAS composite in regard to the development of its modulus of elasticity and compressive strength, as well as in regard to the acoustic emission method during loading.

Experimental study for transient flow rate measurement by means of ultrasonic pulsed Doppler method

This paper reports the investigations of the transient flow rate of the several flow meters and the ultrasonic flowmeter based on the pulsed Doppler method. The reference flow rate is given by the gravimetric method which is newly established in NMIJ. The flow rates are investigated for pulsation flow with 0.5 Hz – 8 Hz frequency. The fluctuations of flow rate by ultrasonic pulsed Doppler method and Coriolis flowmeter are agreed well each other and with the reference flow rate. The influence of the fluctuation of flow rate is less than 2% for the pulsed Doppler method. The result gives new advantage, which is high response for transient flow, for the ultrasonic flowmeter based on the pulsed Doppler method.

Experimental studies of two-phase liquid metal-gas chain flow with ultrasonic echo pulse method and in the magnetic field of permanent magnets

Metallurgical processes of refining and degassing liquid metals are related to the blowing-in neutral gasses like for example argon. Effectiveness of the process depends on the flowing gas parameters like: dimensions, velocity, distribution amd gas phase flow zone. These parameters can be changed under the influence of outside magnetic field and formed by it a Lorentz’ force. In order to get full information of rising bubbles essential are certain measuring methods. Among many of these the ultrasonic echo pulse method is likely to be the most intensive developed in the past few years. That method enables estimation of gas phase flow parameters in a range from individual bubble flow up to full continuous gas flow at the inlet nozzle. In this paper a measurement principle has been described for an ultrasonic echo method and there also submitted and discussed results of obtained results for diphase flow of GaInSn-argon.

Experimental Ultrasonic Study of the Elastic Modulus of Glass Fiber Plastics in Constructions

Results of experimental study of the elastic modulus of composite polymer materials (glass fiber plastics) by a pulsed ultrasonic method are considered. Results of the in situ elastic-modulus testing in isotropic, transverse-isotropic, and orthotropic glass fiber plastics in articles and constructions are presented. A significant distinction between a dynamic elastic modulus determined by the speed of ultrasound and a static one measured according to GOST (State Standard) 9550-81 is demonstrated. Results of studying the anisotropy of fiber glass plastics are provided.

Engineering Investigations and Durability Problems of the Construction Materials of the Roman Babylon of Egypt

The Babylon of Egypt was constructed in the Roman period (300 AD), in the old Cairo area. It is one of the most distinguished monuments in the universal architectural heritage. The present study introduces the characteristics of roman and byzantine bricks and their joining structural mortars used in the roman fortress in order to risk assessment and to define the necessary characteristics of the intervention retrofitting new materials, which will be used in the ongoing preservation work of this fortress. To achieve such, several analyses and laboratory tests like ultra-sonic pulse method testing (ultrasonic pulse velocity, dynamic modulus of elasticity), uniaxial compression test and Brazilian splitting tension test, were carried out to determine their basic, mechanical and engineering properties, along with the microstructural properties determination using Mercury porosimeter. On the other hand, the morphological description, petrography, mineralogical and microstructural properties were determined using scanning electron microscope equipped by EDS, polarizing light microscopy, XRD and XRF. The obtained results indicated that the joining structural mortars are ranging from medium to stiff, low compacted, having hydraulic properties due to the use of natural furnace slag, brick powder, brick fragments and aggregates that match with the pozzolanic properties and also rich in active silica and alumina. The examinations reveal the use of limestone fractions as coarse aggregates or fillers. On the other hand, the Roman bricks consist mainly on quartz and feldspars embedded in a matrix of iron oxide and burnt clays. Also the obtained results indicated that old bricks were of low apparent specific density (1.4 - 1.7), medium absorption (10% - 20%) and low uniaxial compressive strength (2 - 10 MPa), with Young’s modulus 1.2 to 3 GPa. The ultra-sonic wave velocity is 1.7 to 2 km/s, with dynamic modulus of elasticity 2.4 to 4 MPa. The shear modulus is 917 to 1500 MPa. These results may be due to large pores and cracks into their matrix. Due to their surface roughness, the adhesion with the lime mortars was relatively high.

Physical basics of evaluating elastic characteristics of anisotropic composites by ultrasonic method

As a result of analyzing the generalized Hooke law and wave equations for an anisotropic medium, computational expressions have been derived for evaluating the elastic constants of orthotropic, transversely isotropic, and isotropic media using the propagation velocities of longitudinal and shear elastic waves measured with the pulsed ultrasonic method in the corresponding directions.

Ultrasonic pulse and resonance method–evaluation of the degree of damage to the internal structure of repair mortars caused by exposure to high temperatures

When the repair mortars for the repair of concrete structures are exposed to high temperatures, it results in irreversible changes in their internal structure. These changes can be evaluated both on the basis of the compressive strength and flexural strength, but their evaluation can also be made using dynamic non-destructive methods. The article presents the findings on the use of parameters from the measurement by ultrasonic pulse and resonance method. Changes in the internal structure of repair mortars were evaluated on the basis of the dynamic Young’s modulus of elasticity and relative dynamic modulus of elasticity. The said parameters very well characterize the changes in the internal structure of the repair mortars, and their values decrease with the increasing temperature. Changes in the internal structure of the repair mortars also reduce the compressive strength and flexural strength. The researchers confirmed the suitability of the ultrasonic pulse and resonance method for evaluating the degree of damage to the internal structure of repair mortars exposed to high temperatures.

Thermally Stable Ag-Ag Joints Bonded by Ultrasound-assisted Stress Migration Bonding

Abstract We introduce a Ag-Ag direct bonding process with the aid of ultrasonic bonding, which uses silver “Nano-volcanic eruption of Ag” caused by stress migration at 250 °C. Various preheating temperatures before the ultrasonic pulse and various sputtering methods such as direct current (DC) and radio frequency (RF) have also been evaluated. A novel bonding process which combines ultrasonic bonding and stress migration bonding (SMB) method is established. The bonding achieved a die-shear strength of more than 50 MPa and a nearly-perfect voidless bonding interface. High temperature storage (HTS) test at 250 °C was used to evaluate the thermal-resist ability of bonded SMB joints. The results indicate that the bonded joints show no obvious changes in the interfacial morphology and the die-shear stress after HTS test for 1000 h is still higher than 30 MPa. The thermally-stable SMB joints can be applied to advanced devices such as thin-wafer multi-chip integrations and next-generation power devices.

Non-destructive estimation of modulus of elasticity of wood polymer composite

Dynamic modulus of elasticity (DMoE) of wood polymer composites, prepared with varying proportion of wood content, was determined using flexural vibration and ultrasonic pulse transit time methods. The DMoE was compared with the flexural modulus as measured by standard three point bending test. The elastic modulus of the composite increased with the increasing fiber content. Both vibration methods exhibited a strong linear association with static modulus. DMoE by ultrasonic pulse method was higher compared to flexural vibration method at low wood content and the difference diminished at 50% wood in composites. Both the dynamic modulus were higher as compared to the static modulus at all fiber loadings, however the difference between dynamic and static modulus reduced non-linearly with increasing wood content.

Ultrasonic Pulse Method - Influence of Internal Compressive Stress on Results of Testing Calcium Silicate Bricks

Measuring with ultrasonic pulse method is influenced by various factors, like loading in particular inner tension when material built in a construction is tested. The paper researches influence of inner tension (load) on testing of calcium silicate bricks with ultrasonic pulse method. Calcium silicate bricks were loaded with force corresponding to 0 % (unloaded test specimens), 10 %, 20 %, 50 %, 60 % of ultimate compressive strength with various content of humidity (dried samples, w=2 %, w=8 % and samples saturated with water). It was found that ultrasonic pulse velocity is not considerably influenced at load of 10% and 20% of ultimate strength of bricks. However, ultrasonic pulse velocity considerably decreases after loading at 50% and 60% of ultimate compressive strength. Most of theoretical assumptions concerning mentioned concrete stated in technical literature were confirmed, however, particular values were different because of differences between concrete and calcium silicate bricks.

Engineered bamboo scrimber: Influence of density on the mechanical and water absorption properties

Engineered bamboo scrimber has processed from the raw bamboo culm into a compressed or laminated product with thermosetting resin in the density range of 800–1200kg/m3. The present work investigates the mechanical properties of commercially available engineered bamboo scrimber and compares the results of present work with the existing results in the literature. The main aim of this work is to investigate the influence of bamboo scrimber densities on the mechanical properties. The strength and modulus properties in tensile, compression, shear and flexural were evaluated using the specimens of three different densities. The dynamic modulus of elasticity of bamboo scrimber beams were evaluated using ultra-sonic pulse method. According to the present results it can be concluded that the density have significant influence on the mechanical properties of bamboo scrimber. The long term water absorption was also conducted to analysis the weight gained by the bamboo scrimber having different densities and the results revealed that density of specimen’s influences the water absorption.