• Structural Engineering and Mechanics
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• v.74 no.3
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• pp.313-323
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• 2020

Non-destructive tests are commonly used in construction industry to access the quality and strength of concrete. However, till date there is no non-destructive testing method that can be adopted to evaluate the bond condition of reinforced concrete beams. In this regard, the presented research work details the use of ultra-sonic pulse velocity test method to evaluate the bond condition of reinforced concrete beam. A detailed experimental research was conducted by testing four identical reinforced concrete beam samples. The samples were loaded in equal increments till failure and ultra-sonic pulse velocity readings were recorded along the length of the beam element. It was observed from experimentation that as the cracks developed in the sample, the ultra-sonic wave velocity reduced for the same path length. This reduction in wave velocity was used to identify the initiation, development and propagation of internal micro-cracks along the length of reinforcement. Using the developed experimental methodology, researchers were able to identify weak spots in bond along the length of the specimen. The proposed method can be adopted by engineers to access the quality of bond for steel reinforcement in beam members. This allows engineers to carryout localized repairs thereby resulting in reduction of time, cost and labor needed for strengthening. Furthermore, the methodology to apply the proposed technique in real-world along with various challenges associated with its application have also been highlighted.

• Proceedings of the Korea Concrete Institute Conference
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• 1995.04a
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• pp.136-141
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• 1995

The early evaluation on strength of concrete is useful to achieve on quality control and improvement of properties of concrete. Especially, we could say that the confidence of construction is increased by the increase durability and safety building, due to early evaluation. In this study, was proposed to ultra-sonic pulse method as a early evaluation method for strength of concrete with main parameter, sush as W/C ratio and S/A ratio. The experiment results are summarized to follow as : $\circled1$ The ultra-sonic pulse was decreased as the increase of W/C ratio. $\circled2$ The maximum value for the ultra-sonic pulse velocity and compressive strength was presented in the case of 40% S/A ratio and these value was decreased as the change of S/A ratio over 40% $\circled1$ The relationship of the ultra-sonic pulse velocity and compressive strength on 28days according to the change of W/C and S/A ratio is to be: $F_{28} = -209193R^2 + 384417R - 1763441$(W/C Ratio) $F_{28} = 1726R^2 - 774R - 502 (S/A Ratio)

• Proceedings of the KIEE Conference
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• 2004.11c
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• pp.59-61
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• 2004

For automatic landing of small VTOL UAV, it is necessary to calculate the distance from the UAV and the ground. The distance can be generally measured by a ultra-sonic sensor, but the ultra-sonic sensor has errors according to velocity of a sensor board. To compensate these errors, we proposed a sensor fusion method using a Kalman filter.

• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.1
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• pp.129-136
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• 1999

In this paper, the new non-destructive equation will be proposed and evaluated in comparison to the other foreign's non-destructive equation. Through the comparisons cores strength of mock structure with compressive strength obtained from new non-destructive equation ; rebound hammer, ultra-sonic pulse velocity and combined method, it will be analyzed about application of non-destructive equation. The results are following. The new non-destructive equations follow ; (1) $F_c=9.5R{\cdot}N+62.5$ (2) $F_c=243Vp-739$ (3) $F_c=8.1R_o+205.3V_p-802$ where, $F_c$ : Compressive Strength, $R_o$ : Rebound Number. $V_p$ : Ultra-Sonic Pulse Velocity Trough the result of mock structure test, the combined method is superior to rebound method and ultra-sonic pulse velocity method in the estimation of concrete strength. In order to apply the non-destructive equation of concrete strength to the structures, it is necessary that we should be made process study on the non-destructive equation for estimation of concrete strength in the range, time and strength of application under long-term.

• Journal of the Korean Recycled Construction Resources Institute
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• v.3 no.4
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• pp.320-327
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• 2015

This study implicates a quality evaluation technique for lining concrete using the ultra-sonic technique and proposed a classification for quality evaluation. From the comparison of test results, an improved result comparable to the results by destructive test can be obtained by using averaged transmission velocity of velocities obtained at pure space and central space between two sensors of ultrasonic tester. It is also shown that strength evaluation by ultra-sonic method is not reliable and an evaluation according to the transmission velocities can be improved method for the strength evaluation of concrete.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.4
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• pp.71-78
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• 2007

Schmidt hammer and ultra-sonic method are commonly used for crushed sand concrete compressive strength test in a construction field. At present, various of equations for prediction of strength are present, which have been used in a construction field. The purpose of this study is to evaluate the correlation between prediction strength by presentation equations and destructive strength to test specimen, and find out which is a suitable equation for the construction site. In this study, a strength test was carried out destructive test by means of core sampling and traditional test. The experimental parameter were concrete age, curing condition, and strength level.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.05a
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• pp.795-800
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• 2001

Two evaluation techniques of the tunnel lining concrete using ultra sonic velocity method are developed. Modified linear regression technique is proposed to enhance the corelation between the pulse velocity and the compressive strength of core specimens. And bivariate normal distribution is assumed to evaluate the quality of concrete as a terms of compressive strength. A simple corelation table between the pulse velocity and the compressive strength of core specimens are proposed.

• Proceedings of the Korea Concrete Institute Conference
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• 1994.10a
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• pp.435-440
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• 1994

It is considered to pressing problem that the develpment of the rapid and simple method and measuring instrument, can evaluate for quality of concrete at early period. Accordingly in this paper proposed to earlier evaluation method on quality of concrete using resistance method and ultra-sonic pulse velocity test. It was found to the possibility of development on test method and instrument through a series of fundmental investigation.

• Journal of the Korea Concrete Institute
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• v.19 no.1
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• pp.75-81
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• 2007

Percentage that aggregate of materials that concrete composed about $70{\sim}80%$ of whole volume, therefore influence that quality of aggregate gets in concrete characteristics are very important. Schmidt hammer and ultra-sonic velocity method are commonly used for crushed sand concrete compressive strength test in a construction field. At present, various equations for prediction of strength are present, which have been used in a construction field. The purpose of this study is to evaluate the correlation between prediction strength by present equations and destructive strength to test specimen, and find out which is a suitable equation for the construction site, a strength test was carried out destructive test by means of core sampling and traditional test. The experimental parameters were concrete age, curing condition, and strength level. It is demonstrated that the correlation behavior of crushed sand concrete strength in this study good due to the perform analysis of correlation between core, destructive strength and non-destructive strength.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.3
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• pp.61-67
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• 2001

The remaining life estimation for the aged component is very important because mechanical properties of the compo-nents are degraded with time of service exposure in high temperature etc. The destructive method is widely used for the estimation of material degradation, but it has a difficulty in preparing specimens from in-service industrial facilities. In order to evaluate the feasibility of ultrasonic evaluation method for properties of high temperature materials, 2.25Cr-1Mo steel specimens which were prepared by the isothermal aging heat treatment at 63$0^{\circ}C$ were evaluated by ultra-sonic measurements investigating the change of velocities and attenuation coefficient. In this results, attenuation coefficient was found to be sensitive to material degradation mainly attributed to the change of grain size and the precipitation of impurities in grain boundaries, but velocity was not for all specimens.