• Proceedings of the Korea Concrete Institute Conference
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• 2005.11a
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• pp.619-622
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• 2005

This study concerns the new strength equation of concrete by ultrasonic pulse velocity test. There are not only few estimate strength equations of concrete by ultrasonic pulse velocity test, but also many problems to apply them because of time,. cost, easiness, structural damage, reliability and so on. For this study, there performed a series of test and proposed equations as follows; Linear: ${\Large f}_{ck}=-193.15+60.97Vp\;r^2=77.9\%$ Quadratic : ${\Large f}_{ck}=276.85-189.64Vp+33.22Vp^2\;r^2=80.3\%$ here, $f_{ck}$ : Estimated compressive strength of concrete by MPa Vp : Ultrasonic Pulse Velocity of concrete by km/sec

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.129-132
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• 2004

This study concerns the new strength equation of concrete by ultrasonic pulse velocity test. There are not only few estimate strength equations of concrete by ultrasonic pulse velocity test, but also many problems to apply them because of time, cost, easiness, structural damage, reliability and so on. For this study, there performed a series of test and proposed equations as follows; $$Linear\;:\;f_{kc}=65.43Vp-207.18\;r^2=80.8\%$$ $$Quadratic\;:\;f_{ck}=42.35Vp^2-250.71Vp+378.8\;r^2=83.7\%$$ here, fck : Estimated compressive strength of concrete by MPa Vp: Ultrasonic Pulse Velocity of concrete by km/sec.

• Journal of the Korea institute for structural maintenance and inspection
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• v.5 no.3
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• pp.123-130
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• 2001

The purpose of this study is to suggest the non-destructive equation for the estimation of concrete strength by ultrasonic pulse velocity at the Age of 28day compressive strength of $600{\sim}1000kg/cm^2$. For this purpose, selected test variables were water-hinder ratio, replacement ratio of silica fume, binder content, maximum size of coarse aggregate and sand-aggregate ratio. From the results, the average increase or decrease of ultrasonic pulse velocity is 61m/sec for each 1% of moisture content. And the correlation equation between the ultrasonic pulse velocity and the compressive strength of concrete is as follows. $F_c=896.3V_p-3514$ ($R^2$ = 0.81) where, $F_c$ : compressive strength($kgf/cm^2$), $V_p$ : ultrasonic velocity(km/sec).

• Magazine of the Korean Society of Agricultural Engineers
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• v.43 no.4
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• pp.97-105
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• 2001

The ultrasonic pulse velocity test has a strong potential to be developed into a very useful and relatively inexpensive in-place test for assuring the quality of concrete placed in structure. The main problem in realizing this potential is that the relationship between compressive strength ad ultrasonic pulse velocity is uncertain and concrete is an inherently variable material. The objective of this study is to improve the reliability of in-place concrete strength predictions by ultrasonic pulse velocity method. Experimental cement content, s/a rate, and curing condition of concrete. Accuracy of the prediction expressed in empirical formula are examined by multiple regression analysis and linear regression analysis and practical equation for estimation the concrete strength are proposed. Multiple regression model uses water-cement ratio cement content s/a rate, and pulse velocity as dependent variables and the compressive strength as an independent variable. Also linear regression model is used to only pulse velocity as dependent variables. Comparing the results of the analysis the proposed equation expressed highest reliability than other previous proposed equations.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.6
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• pp.173-179
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• 2008

This paper aims to calculate age coefficient of ultrasonic pulse velocity by non-destructive test. When concrete compressive strength is measured by non-destructive test, rebound test hammer method is applied to estimate age coefficient depending on the course of time after concrete casting, but ultrasonic pulse velocity method is not applied in the process. Although it is necessary to consider age coefficient with change of ultrasonic pulse velocity of concrete depending on aging, there have been little attempts to apply that method. The experiments were conducted to calculate aging effects which will be applied to establish the formula of measuring concrete strength. As a result of experiments, it was found that ultrasonic pulse velocity showed radical changes depending on concrete hardening in comparison with initial standard values. So, it was concluded that age coefficient must be applied to calculate strength. In conclusion, age coefficient of ultrasonic pulse velocity of concrete was suggested on the basis of experimental results.

• Structural Engineering and Mechanics
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• v.64 no.4
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• pp.427-436
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• 2017

Concrete technologists have used ultrasonic pulse velocity test for decades to evaluate the properties of concrete. However, the presented research work focuses on the use of ultrasonic pulse velocity test to study the degradation in steel-concrete bond subjected to increasing loading. A detailed experimental investigation was conducted by testing five identical beam specimens under increasing loading. The loading was increased from zero till failure in equal increments. From the experimentation, it was found that as the reinforced concrete beams were stressed from control unloaded condition till complete failure, the propagating ultrasonic wave velocity reduced. This reduction in wave velocity is attributed to the initiation, development, and propagation of internal cracking in the concrete surrounding the steel reinforcement. Using both direct and semidirect methods of testing, results of reduction in wave velocity with evidence of internal cracking at steel-concrete interface are presented. From the presented results and discussion, it can be concluded that the UPV test method can be successfully employed to identify zones of poor bonding along the length of reinforced concrete beam. The information gathered by such testing can be used by engineers for localizing repairs thereby leading to saving of time, labor and cost of repairs. Furthermore, the implementation strategy along with real-world challenges associated with the application of the proposed technique and area of future development have also been presented.

• Journal of architectural history
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• v.24 no.5
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• pp.41-48
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• 2015

Quantitative analysis of termites damage is important in terms of conservation and maintenance of wooden cultural heritage buildings, because termites makes cavities and decreases the section area of wooden structural members. The purpose of this study is to forecast the range and spread of termites damage in the wooden structural members by using ultrasonic pulse velocity method. Ultrasonic pulse velocity has been used as one of non-destructive test to analysis the internal defect by using difference velocity between medium material and cavity. This method would be effective to analysis termites damages. From the result of the ultrasonic velocity test, the loss rate of area effected by termites damage had a strong correlation with ultrasonic velocity. And it is possible to predict the loss rate of area from by termites damage by using regression equation in the case of structural member of fine tree.

• Proceedings of the Korea Concrete Institute Conference
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• 1998.04b
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• pp.707-711
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• 1998

Ultrasonic test usually was used for defect detection, crack depth measurements and strength estimation of hardened concrete. The essence of the pulse velocity method is that the transition time of an ultrasonic longitudinal pulse is measured in concrete. Ultrasonic velocity was propagated to the age of concrete, made a radical change at that time when concrete was setted. This study which monitored the change in a concrete by ultrasonic test was performed to estimate initial setting and final setting.

• Journal of the Korean Wood Science and Technology
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• v.43 no.4
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• pp.486-493
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• 2015

The ultrasonic nondestructive test (NDT) was applied to deck in-service to inspect and evaluate the performance of decking materials using ultrasonic pulse velocity. First, the measuring method between direct and indirect method according to transducer arrangement was studied. Second, the ultrasonic pulse velocity of decks in-service was compared with the passage of time. Finally, the change of ultrasonic pulse velocity was evaluated to expect service life of decking materials. The results of comparison between direct and indirect method was statistically insignificant and the ratio of direct to indirect method was 1.02. 1.05 respectively. The ultrasonic pulse velocity of decks in-service was decreased as the passage of time and the linear relationship in the ultrasonic pulse velocity to passage of time was found. From the results, The ultrasonic NDT will be helpful as an efficient method of on-site management of decks in-service.

• Structural Engineering and Mechanics
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• v.65 no.5
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• pp.601-609
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• 2018

Steel bolts are used in the construction industry for a large variety of applications that range from fixing permanent installations to temporary fixtures. In the past much research has been focused on developing destructive testing techniques to estimate their pull-out load carrying capacity with very little attention to develop non-destructive techniques. In this regards the presented research work details the combined use of ultrasonic pulse velocity and Schmidt hammer tests to identify anchor bolts with faculty installation and to estimate their pull-out strength by relating it to the Schmidt hammer rebound value. From experimentation, it was observed that the load capacity of bolt depends on its embedment length, diameter, bond quality/concrete strength and alignment. Ultrasonic pulse velocity test is used to judge the quality of bond of embedded anchor bolt by relating the increase in ultrasonic pulse transit time to the presence of internal pours and cracks in the vicinity of steel bolt and the surrounding concrete. This information combined with the Schmidt hammer rebound number, R, can be used to accurately identify defective bolts which resulted in lower pull-out strength. 12 mm diameter bolts with embedment length of 70 mm and 50 mm were investigated using constant strength concrete. Pull-out load capacity versus the Schmidt hammer rebound number for each embedment length is presented.