Ultrasonic Velocity Method Research Articles

Statistical Reliability Analysis of Ultrasonic Velocity Method for Predicting Residual Strength of High-Strength Concrete under High-Temperature Conditions.

Herein, we conducted a comprehensive statistical assessment of the ultrasonic pulse velocity (UPV) method's effectiveness in predicting concrete strength under diverse conditions, specifically early age, middle age, and high-temperature exposure. The concrete mixtures, with water-to-cement (W/C) ratios of 0.33 and 0.28, were classified as granite aggregate or coal-ash aggregate mixes. Compressive strength and UPV measurements were performed under these conditions, and subsequent statistical analyses treated the identified factors as distinct groups. The results revealed a substantial difference in compressive strength between specimens at early age (average of 13.01) and those at middle age (average of 41.96) and after high-temperature exposure (average of 48.08). Conversely, UPV analysis showed an insignificant difference between the early-age specimens and those after high-temperature exposure. The analysis of the W/C ratio and coarse aggregate demonstrated significant differences (p-value < 0.05) in compressive strength between specimens in middle age and those exposed to high temperatures, excluding the early-age specimens. However, UPV analysis revealed insignificant differences, with p-values of 0.67 and 0.38 between specimens at an early age and post-high-temperature exposure, respectively. Regression analysis identified suitable functions for each scenario, emphasizing the importance of a strength prediction model for concrete after high-temperature exposure, particularly considering the W/C ratio. Since concrete showed statistically different compressive strength, UPV, and strength prediction models in three conditions (early age, middle age, and high temperature), different strength prediction models must be used for the purpose of accurately predicting the strength of concrete.

Physicochemical Properties of Cetrimonium Bromide in Electrolytes and Nonelectrolyte Environments

Background: The physicochemical properties, including the thermodynamics of micellization studies, received much attention. Cationic surfactant cetrimonium bromide (C16TABr) in electrolytes (sodium chloride and sodium salicylate) and nonelectrolyte (Ethylene glycol) in an aqueous solution were examined, and interesting results were obtained. The present investigation aims to identify a suitable combination of cationic surfactant cetrimonium bromide + electrolytes and nonelectrolytes having the ability to alter the size or shape of the micellar system using available methods. Methods: Surface tension, conductivity, viscosity, ultrasonic velocity, and dynamic light scattering (DLS) methods at different temperatures (303-323K) were used during the experimental research work. Results: The experimental results pointed out that the incorporation of electrolytes and nonelectrolyte into the cationic surfactant affects the physicochemical properties such as critical micelle concentration (CMC), surface tension (ST), degree of ionization (α), degree of counterion binding (β), standard Gibbs free energy of micellization (ΔGo m), standard entropy of micellization (ΔSo m), standard heat of micellization (ΔHo m), viscosities, and acoustic parameters. Dynamic light scattering (DLS) measurements reveal exciting facts related to the size and shape transformation of the mixed micellar assembly. Structure modification can be obtained by choosing right the combination of cationic surfactant cetrimonium bromide + electrolytes (sodium chloride and sodium salicylate) and nonelectrolyte (Ethylene glycol) ratio. Conclusion: It concluded that, over a threshold level, an electrolyte such as NaCl concentration causes the micelle size to rise. The entropy of micellization goes down when a structure-breaker (EG) is added to the water phase, and this is because the structure of the water is changed near hydrophobic groups. The physicochemical features of cetrimonium bromide (C16TABr) show unique behaviour under the influence of micelle-driven and micelle- forbidden systems.

Thermodynamic Properties of Pyridine Based 1,3,4-Oxadiazole Scaffolds

Background: The present work describes the synthesis, characterization, and thermo-acoustical parameters of binary solutions of 1-(2-(4-fluorophenyl)-5-(pyridin-4-yl)- 1,3,4-oxadiazol-3(2H)-yl)-3-(pyridin-2-yl)prop-2-en-1-one, (AS1-08) and 1-(2-(4- methoxyphenyl)-5-(pyridin-4-yl)-1,3,4-oxadiazol-3(2H)-yl)-3-(pyridin-2-yl)prop-2-en-1- one, (AS1-12) in dimethyl sulfoxide (DMSO) and N, N-dimethylformamide (DMF) were estimated. Methods: Viscosity, ultrasonic velocity, and density methods at different solvents (DMSO and DMF) and different temperatures (298.15, 308.15, and 318.15 K) were used during the experimental research work. Results: Some acoustic parameters such as adiabatic compressibility (κs), intermolecular free path length (Lf), Rao’s molar sound function (Rm), Van der Waals constant (b), internal pressure (π), free volume (Vf) and solvation number (Sn) were calculated. The results obtained were interpreted in terms of solute-solvent and solute-solute interactions. Conclusion: The thermodynamic and various acoustical properties were determined at three different temperatures viz. (298.15, 308.15, and 318.15 K) at atmospheric pressure. Likewise, the similarity between experimental results of the binary solutions was studied to analyze how the change in the structural modification and solvent changes the values of Gibbs energy of activation (ΔG*), enthalpy of activation (ΔH*), and entropy of activation (ΔS*).

Research on Measuring System of Sodium Hydroxide Concentration in Impregnation Solution Based on Ultrasonic Velocity Method

A sound velocity measurement system based on FPGA was designed. The time of flight was calculated by using the wave crest of ultrasonic signal to achieve high precision measurement of sound velocity. The high-speed data communication between field programmable gate array (FPGA) and host computer system is realized by using AN9238, DPRAM and 485 communication port. On the basis of FPGA hardware, high-speed AD chip is used for sampling to complete data storage and processing. The experimental results show that compared with the standard system, the time-of-flight measurement accuracy of the designed system is 0.1㎲, and the measurement accuracy of the solution sound velocity is better than 2 m/s, which verifies the reliability of the scheme.

Characterization on vermicular graphite rate and tensile strength in vermicular graphite cast iron based on nonlinear ultrasonic technique

Ultrasonic techniques have been widely used to detect the percentage of vermicular graphite, defects, etc. in vermicular graphite cast iron. The linear ultrasonic velocity method is the main ultrasonic method for characterizing vermicular graphite rate and tensile strength in the current study, however, it is often easy to misjudge the vermicular graphite rate due to its insignificant variation. This study explores the feasibility of using the nonlinear ultrasonic technique (NUT) to characterize the vermicular graphite rate and tensile strength. Based on the longitudinal critically refracted (LCR) wave detection model, an experimental study to detect the vermicular graphite rate and tensile strength of vermicular graphite cast iron is carried out using the nonlinear ultrasonic harmonic method, and compared with the ultrasonic velocity method. The experiment results show that the relative nonlinear parameter of the LCR wave decreases along with the increase of vermicular graphite rate and increases along with the increase of tensile strength, and it has higher detection sensitivity and resolution than ultrasonic velocity by analyzing the obtained data. The increase in the acoustic nonlinearity parameter (ANP) is related to the increase in the number of grain boundaries in the microstructure. Therefore, the relationship among microstructure, ANP, and mechanical properties of vermicular graphite cast iron can be established, and it’s promising that a new approach might be developed for quickly detecting the vermicular graphite rate and corresponding tensile strength with the NUT.

Strength Prediction of Non-Sintered Hwangto-Substituted Concrete Using the Ultrasonic Velocity Method.

This paper presents and investigates the properties of concrete in which a portion of the cement is substituted with non-sintered Hwangto (NSH), a readily available building material in Asia. Given the inactive nature of NSH, this study aimed to determine the optimal cement replacement ratio and quantitative strength of the material. The unit weight, compressive strength, ultrasonic pulse velocity (UPV), and stress-strain of the NSH concrete (NSHC) were evaluated. Additionally, we developed a predictive model for determining compressive strength based on the regression analysis of compressive strength and UPV. The water-to-binder ratio was set to 0.41, 0.33, and 0.28, and the NSH replacement rates in the cement were set to 0%, 15%, 30%, and 45% for evaluating various strength ranges. The mechanical property measurements indicated reductions of 5.35% in unit weight, 35.62% in compressive strength, and 6.34% in UPV as the NSH was replaced. Notably, the smallest deviation from plain concrete was observed at a replacement rate of 15%. The scanning electron microscopy analysis results showed that the plain concrete exhibited a crystalloid structure; however, as the NSH replacement rate increased, the amorphous structure and pores increased while unreacted NSH particles were also observed. The X-ray diffraction analysis results demonstrate that the peak intensities for kaolinite and mullite increased as the NSH replacement rate increased, while those of C-S-H gel and CaO showed low peak intensities. Furthermore, the regression analysis concluded that an exponential function was suitable. Consequently, a compressive strength prediction model was developed, and in the error test, the NSHC model demonstrated an average error of <10%, with fewer errors at the lower compressive strength boundaries.

A Study to Improve the Reliability of High-Strength Concrete Strength Evaluation Using an Ultrasonic Velocity Method.

The ultrasonic pulse velocity (UPV) technique, which is an efficient technique for concrete quality evaluation, can be affected by several factors. Many studies have proposed compressive-strength prediction models based on UPV in concrete; however, few studies have investigated the factors resulting in statistically different UPV results for different models. This study examined the difference between compressive strengths of various concrete specimens calculated by age-dependent and temperature-dependent UPV-based prediction models. Furthermore, a statistical analysis was conducted to evaluate the influence of aggregates and water/cement ratio (design compressive strength), which are said to affect UPV, on the compressive-strength prediction models. The experimental results revealed that the residual compressive strength of concrete after high-temperature exposure was about 9.5 to 24.8% higher than the age-dependent compressive strength. By contrast, after high-temperature exposure, UPV tended to be about 34.5% lower. The compressive strengths and UPVs were significantly different with respect to high temperature, aggregate density, and design compressive strength. The compressive-strength prediction model derived from the regression analysis showed a high R2 (average 0.91) and mean error converged to zero compared to the compressive-strength prediction model without considering these factors. Finally, the differences between the age- and temperature-based compressive-strength prediction models were analyzed according to the corresponding microstructures.

Numerical simulation of ultrasonic velocity in wet steam

Wet steam widely exists in thermal power plants, nuclear power plants and other power engineering. The accurate measurement of steam wetness is very important for the safety and economy of power engineering. Ultrasonic method is feasible to measure the concentration of two-phase flow in particle system. In order to obtain a theoretical model of ultrasonic velocity which can be applied to high flow velocity conditions (Reynolds number > 4000), the numerical results of several ultrasonic propagation characteristics theoretical models are compared with the experimental results. The calculated results of U-A coupled phase model show good agreement with the experimental results (the max error is 3.8%), and the model is more suitable for the numerical calculation of ultrasonic sound velocity in droplet two- phase flow with high flow velocity. The ultrasonic sound velocity of steam system in nuclear power plant is calculated numerically. When the droplet size is less than 8 μm, the sound velocity is sensitive to the variation of the droplet size, and when the droplet size is larger than 8 μm, the sound velocity is almost unaffected (velocity variation <0.5%) by the fluctuation of the droplet size. When the effect of the droplet size change on sound velocity can be ignored, the ultrasonic sound velocity method combined with U-A coupled phase model can be used to measure the steam wetness online.

Damage Characteristics and Energy Evolution of Bituminous Sandstones under Different Cyclic Amplitudes

In many underground engineering projects, rocks are often subjected to cyclic loading and unloading, such as repeated excavation of roadway surrounding rock, which will lead to damage to underground rocks, and the energy of rocks also changes. Therefore, to study the energy evolution and damage characteristics of rocks under cyclic loading and unloading, different cyclic loading and unloading tests of bituminous sandstones under constant amplitude were conducted. Under cyclic loading and unloading, the lower limit stress was 40% of the rock peak intensity, the cyclic amplitude was 20–40% of the peak intensity, and the number of loading–unloading cycles was 10–30. The quantitative characterization of the damage degrees of bituminous sandstone was realized by the ultrasonic wave velocity and elasticity modulus methods. The energy evolution and damage characteristics of bituminous sandstone under different amplitudes and number of loading–unloading cycles were investigated through the energy dissipation method. Results showed that under cyclic loading and unloading, the ultrasonic wave velocity and elasticity modulus of bituminous sandstone decreased gradually; The damage variable shows a trend of rapid and then stable growth and has a power function relationship with the number of cycles; The input energy density and dissipation energy density curves were in L-shaped distribution, whereas the elastic energy density remained stable. The results of this study can provide some theoretical references to underground engineering construction.

Determination of compressive strength of lightweight aggregate concrete in service using gene expression programming based on semi‐direct ultrasonic pulse velocity testing

AbstractStructural lightweight aggregate concrete (SLWAC) can increase the ability of buildings to resist earthquakes by significantly reducing the overall weight of structures. Determining a relationship for assessing the concrete compressive strength of these structures using non‐destructive methods can save both time and money. This study aims to estimate the compressive strength of SLWAC using a model of gene expression programming (GEP) and semi‐direct ultrasonic pulse velocity. A hundred specimens of lightweight concrete were made using clay and natural (mineral) pumice aggregates with the maximum nominal sizes of 12.7 mm (½ inch) and 19.2 mm (¾ inch), respectively. Semi‐direct ultrasonic testing of the specimens was then undertaken in the laboratory. The results show a high correlation coefficient for the equations derived from the GEP. Moreover, the equations obtained from GEP for three types of SLWAC, based on semi‐direct ultrasonic pulse velocity, are compatible with equations obtained from the direct ultrasonic velocity method. The simplicity of generated equations increases the practicality and convenience in the working environment and actual conditions. The R2 (goodness of fit) values of proposed equations for LWA01, LWA02, and LWA03 specimens were 0.912, 0.962, and 0.985, respectively. It was concluded that based on the semi‐direct ultrasonic pulse velocity and derived formulas, the compressive strength of SLWAC can be confidently predicted using GEP.

The Dependence of Ultrasonic Velocity in Ultra-Low Expansion Glass on Temperature

The coefficient of thermal expansion (CTE) is an important property of ultra-low expansion (ULE) glass, and the ultrasonic velocity method has shown excellent performance for the nondestructive measurement of CTE in large ULE glass. In this method, the accurate acquisition of the ultrasonic velocity in ULE glass is necessary. Herein, we present a correlation method to determine the ultrasonic TOF in ULE glass and to further obtain the ultrasonic longitudinal wave velocity (cL) indirectly. The performance of this method was verified by simulations. Considering the dependence of cL on temperature (T), we carried out the derivation of the analytical model between cL and T. Based on reasonable constant assumptions in the physical sense, a cL–T exponential model was produced, and some experimental results support this model. Additional experiments were carried out to validate the accuracy of the cL–T exponential model. The studies we conducted indicate that the cL–T exponential model can reliably predict the ultrasonic velocity in ULE glass at different temperatures, providing a means for the nondestructive CTE measurement of large ULE glass at a specified temperature.

Guar gum (GG) / Methylcellulose (MC) Blends and their Composites with Maghemite Nanoparticles

Miscibility of polymers decides the applicability of the resulting blends and immiscible polymer blends can be made compatible with suitable compatibilizer. Miscibility of blends of guar gum (GG) and methyl cellulose (MC) in common solvent water were studied by refractive index, density, ultrasonic velocity, and dilute solution viscometry methods at 30°C and 40°C. Based on these measurements, it is found that the polymer blend of GG/MC is immiscible. The effect of compatibilization with 0.02 wt% maghemite nanoparticle was studied in aqueous solution and found that 10/90 GG/MC blend is miscible in the presence of maghemite. Solution cast technique was used to prepare thin films of GG/MC blend – maghemite composite and characterized by scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) method.

Exploration of thermoacoustics behavior of water based nickel ferrite nanofluids by ultrasonic velocity method

Magnetic nanofluids (commonly known as ferrofluids) have captured the great attention of the researchers due to their various kinds of applications such as heat transfer, hyperthermia treatments, targeted drug delivery etc. The present experimental investigations deal with the thermoacoustic behaviour of the water based nanofluids of nickel ferrites. The magnetic nickel ferrite nanoparticles were produced by the simple and inexpensive chemical co-precipitation route. The prepared nanoparticles were exposed to different characterization tools for structural, morphological, compositional and magnetic properties analysis. X-ray diffraction analysis with Rietveld refinement confirmed the single phasic nature with nanometric crystallite size of the prepared nanoparticles. Scanning electron microscope images revealed the spherical and nanocrystalline morphology of the prepared nanoparticles. The M-H plot recorded at room temperature revealed the superparamagnetic nature of the nanoparticles. Further, the co-precipitated nickel ferrite nanoparticles with different concentrations were utilized for the preparation of the water based magnetic nanofluids. Colloidal stability of the prepared nanofluids was analyzed by UV–Vis spectroscopy technique and it revealed the stability over 11 days without separation in phase. The temperature dependent thermoacoustic properties of the prepared nanofluids were analyzed through Ultrasonic Interferometer. The interaction between particle–particle and particle–fluid are explained on the basis of thermo-acoustic parameters.

Kocaeli Tarihi Cami Örnekleri Üzerinden Planlı Koruma Kapsamında Hasarsız Test Uygulamaları: Çoban Mustafa Paşa Camii, Fevziye Camii Ve Pertev Paşa Camii

The conservation of historical buildings via charters, general principles, methods for maintenance and repair of the buildings have been analysed in the international environment. Theories, approaches and conservation methods have been adopted along with the developing technology in relevance with the current conditions. Conservation is a process including consistent, coordinated and programmed activity of study, prevention (limiting situation of risk), maintenance (controlling the conditions of property) and restoration (direct intervention). In this regard, the significance of non-destructive tests on existing historical buildings –in the context of planned conservation- should be highlighted, and become widespread. In Turkey, which is extensively rich in historical building stocks, it is a difficult task to appraise the physical conditions of all historical buildings by non-destructive tests with a limited number of experts. On the contrary, appraisal of present conditions of building stocks and detailed diagnostics phase of the buildings are important in terms of conscious and sustainable conservation. The buildings under the effect of interior and ambient environmental conditions and decays developed on building envelope or structural elements causing from these conditions affect the structure and thermal comfort conditions in a negative way. Continuous monitoring of these actions causing decay and degradations prevent the structure to be under high risk and the necessity of performing heavy interventions on buildings. By the non-destructive test applications during monitoring, the buildings are prevented to be under high risks and the necessity for heavy interventions can be eradicated. In this research, Pertev Pasa Mosque -constructed by Architect Sinan-; Gebze Coban Mustafa Pasa Mosque -constructed in 1523 and known as the work of Architect Sinan but various names asserted as the architect of building according to resources-, and Fevziye Mosque -initially constructed by Architect Sinan in 1576 but then destroyed and re-constructed due to disasters in the past and finally heavily damaged on 17 August 1999 then re-constructed- are analysed. Three mosques are listed by national protection board and they were investigated without any damage to the buildings. All structures whose original construction dates back to 16th century were selected according to three criteria: Pertev Pasa Mosque and Fevziye Mosque are exposed to same climatic conditions due to their close locations to each other; on the other hand Fevziye Mosque display different material and construction system due to the subject of being reconstructed several times. Coban Mustafa Pasa Mosque, conserved well like Pertev Pasa Mosque in terms of material, construction system and architectural properties, is located in a different place with respect to others. The outcome and methods of the project 114K284, Non-Destructive Test Applications, in the Context of Planned Conservation, through Historical Mosques of Kocaeli: Coban Mustafa Pasa Mosque, Fevziye Mosque and Pertev Pasa Mosque”funded by TUBITAK, are presented in this paper. Temperature and relative humidity values of inside and ambient environments are were measured by dataloggers and probes for three mosques. The visual and quantitative data of the buildings were obtained to appraise degradation of building envelope and define micro-climatic conditions of the materials by Infrared Thermography and Ultrasonic Velocity Methods. Condensation risk in the mosques by logging inside and ambient environment temperature and relative humidity level were found high considering praying times. Existing and possible deteriorations and previous interventions were found via infrared thermography captures. Moreover, the voids inside the building envelope and qualitative properties of materials were revealed by tests.

Influence of silica fume on the dynamic properties of concrete

Ultrasonic pulse velocity and resonance frequency methods are non-destructive tests that allow the evaluation and control of building materials. They have been used to determine the dynamic properties of concrete, which are used in the design and control of structures and which are the key elements of the dynamics of materials. In this study, we chose a non-destructive approach to quantify -in laboratory-, the influence of adding “silica fume” on ordinary concrete’s dynamic characteristics. However, several concrete mixtures have been prepared with limestone aggregates. The experimental plan used, allowed us to determine the dynamic elasticity modulus and the dynamic rigidity modulus of different formulated concretes.

Particle interaction energy and hysteresis in polar and non-polar medium based magnetic fluids

The inner structural properties of two different types of magnetic fluids (MFs) under the application of an external magnetic field were experimentally investigated by using the ultrasonic propagation velocity method. Because the inner structure of the MF subjected to an external magnetic field mainly depends on parameters such as the medium, particle–particle interaction, and hysteresis, the ultrasonic velocity method was used to investigate the detailed structural formation of particles in both polar and non-polar medium based MFs. The experimental data were analyzed by incorporating the distribution of the particle moments by using Tarapov’s theoretical model. Based on the results, the inner structures of the prepared MFs were analyzed in terms of the effect of the medium, while the effects of Brownian mechanism and interaction phenomena in the presence of the external magnetic field were considered. In addition, the results presented reveal anisotropy and hysteresis in the MFs subjected to the external magnetic field.

Applicability of Ultrasonic Measurement on the Monitoring of the Setting of Cement Pastes: Effect of Water Content and Mineral Additions

Abstract Until now, standardized methods developed for the detection of initial and final setting time of cement paste were destructive and non-continuous. The well-established ultrasonic pulse transmission velocity (UPV) method can be correlated to the setting process of cement-based materials by the measurement of P-waves. However, S-waves seem to be better indicators of the setting of cement-based materials, because they are more sensitive to the solid matrix connectivity and less dependent to the air content. A new methodology, based on the combined monitoring of P-waves and S-waves, has already been developed to determine the setting times of mortar and concrete. The purpose of this study is to extend this methodology to cement pastes. Ordinary portland cement pastes with three water/cement ratio between 0.3 and 0.5 have been investigated. In addition, a portland cement, blast-furnace slag and limestone filler blended cement paste with a 0.4 water/cement ratio is studied in order to validate all observations. This study shows that the dynamic elastic properties can be linked to the initial and final setting times of cement paste. The early age evolution of the elastic properties depends on the air content and the binder nature. The combined monitoring of P-waves and S-waves provide accurate indicators of the setting process.

Estimation of Thickness of Concrete Structures using the Impact Echo Method and Ultrasonic Pulse Velocity Method

The structure must be periodically checked and measures must be taken to prevent deterioration in building construction. From this point of view, a nondestructive test is essential to estimate whether the construction of buildings is proper, and whether the dimension of depositing concrete is consistent and without damage. This study estimated the thickness of the concrete component of construction framework using the ultrasonic velocity method and the impact echo method, in order to investigate reliability of the estimation of the thickness of normal strength concrete and high strength concrete, leading to the following conclusions. In the estimation of the thickness of the concrete structures, specimens of normal strength of 24MPa and specimens of high strength of 40MPa demonstrated an average error rate of 5.1% and 2.2%, respectively. The impact-echo method, one of the non-destructive tests, is verified as an efficient diagnostic technique. With this information, we will determine specific standards for the maintenance of structures, and the re-creation of lost building blueprints.

표면반발경도와 초음파 속도를 활용한 고강도 콘크리트 압축강도 추정

Abstract: The authors performed the experimental work to propose the strength prediction equation for high strength concrete based on thenon-destructive test methods. The concrete specimens that the range of design compressive strength was 40~80 MPa was produced i n laboratory, and then tested rebound test and ultrasonic velocity methods and also compressive test according to the Korea Standard. The tes t results was compared with previously equations suggested by other researcher. From the test, these traditional nondestructive methods are simple, qu ick, has proven to be reliable and useful method for predicting the concrete strength. The test results were compared with the previous equations and then newly proposed own equations based on the test results. The proposed equations have the suitable precision and accuracy for applying the high strength concrete structuresKeywords: Rebound test, Ultrasonic pulse velocity, High strength concrete, Compressive strength 1 정회원, 지진방재연구센터 연구원

충격공진법과 초음파속도법을 통한 콘크리트 압축강도 예측의 신뢰성 평가

Non-destructive testing (NDT) methods are widely used in the construction industry to diagnose the defects/strength of the concrete structure. However, it has been reported that the results obtained from NDT are having low reliability. In order to resolve this issue, four kinds of NDT test (ultrasonic velocity measurements by P-wave and S-wave and the impact resonance methods by longitudinal vibration and deformation vibration) were carried out on 180 concrete cylinders made with two kinds of mix proportions. The reliability of the NDT results was analyzed and compared through the measurement of the actual compressive strength of the concrete cylinders. The statistical analysis of the results was revealed that the ultrasonic velocity method by S-wave is having lowest coefficient of variation and also most capable of stable observation. Analytical equations were established to estimate the compressive strength of the concrete from the obtained NDT results by relating the actual compressive strength. Moreover the equation established by the ultrasonic velocity method by S-wave had the highest coefficient of determination. Further studies on the stability of non-destructive testing depending on various mixing conditions will be necessary in the future.