Compressive Strength Calculation Using Ultrasonic Pulse Velocity Method

Compressive Strength Calculation Using Ultrasonic Pulse Velocity Method

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Rehabilitation/Improvements to AB 019 – Jaffna-Pannai-Kayts Road Ultrasonic Pulse Velocity Test Ultrasonic Pulse Velocity Tester (PUNDIT 6) is used to determine the compressive strength of the concrete by using the Ultrasonic wave. The pulse velocity is depending on the hardness of the concrete. Compressive strength can be calculated aid of velocity with a correlation. Relevant Standard    

BS 1881:Part 203:1986 Recommendations for measurement of velocity of ultrasonic pulse in concrete BS 1881:Part 204:1988 Recommendations on the use of electromagnetic converter Guidebook on Non-destructive testing of concrete structures by International Atomic Energy Agency, Vienna-2002 Operating manual of PUNDIT 6

Theory A pulse of ultrasonic stress waves is introduced into one surface of a concrete member by a transducer coupled to the surface with a coupling gel or grease. The pulse travels through the concrete and is received by a similar transducer coupled on the opposite surface. The transit time of the pulse is determined by the instrument. The distance between the transducers is divided by the transit time to obtain the pulse velocity. Using the pulse velocity compressive strength and concrete quality can be determined. Procedure 

Two types of transmission methods will be used. They are direct transmission and indirect transmission. a) Direct transmission If the both surfaces are accessible, direct transmission method will be used.

b) Indirect Transmission If only one surface is accessible, indirect transmission will be used.

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    

Test surfaces will be cleaned properly to avoid extraneous materials. Coupling agent will be applied both faces to proper wave transfer. Transducer and receiver will be place according to the direct method or indirect method. Distance between transducer and receiver will be measured nearest first decimal place in centimeter and transit time is obtained in micro seconds. Ultrasonic pulse velocity will be calculated according to the following equation.





o

Where;

o

Where;

V - Ultrasonic pulse velocity  L –Distance of wave transferred  T – Time to travel receiver If indirect method will used, following equation will be used to convert the velocity.





V0 - Pulse velocity obtained using the direct method  V1 - Pulse velocity obtained using the indirect method  (Ref: Operating manual of PUNDIT 6) Using the pulse velocity compressive strength and concrete quality will be determined.

Note – See the attached example test report

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Pulse Velocity to Strength This is a method by which the concrete strength can be calculated using a combination of the rebound value of the concrete and the UPV. Using these two independent factors will give greater accuracy, but must be calibrated using local materials. 01. After attaining relevant pulse velocity for the structure, concrete strength and density is attained from the calibration chart. (Pulse Velocity Vs. Strength and Pulse Velocity Vs. Density). 02. The Calibration chart for strength has attained by taking rebound test results and cube crushing test results.

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