PULSE-VELCOITY TECHNIQUES AND EQUIPMENT FOR TESTING CONCRETE
THE HISTORY OF THE USE OF PULSE-VELOCITY FOR THE TESTING OF CONCRETE IS PESENTED ALONG WITH SOME OF THE TESTING EQUIPMENT. PULSE-VELOCITY CAN BE USED AS A MEASURE OF STRENGTH, SETTING CHARACTERISTICS, DYNAMIC MODULUS, AND CRACKING IN CONCRETE. THE PULSE- VELOCITY MEASURING DEVICES DEVELOPED TO DATE FALL INTO THREE CLASSES-SINGLE-BLOW, ULTRASONIC, AND REPETITIVE-BLOW. THE FIRST INCLUDES THOSE IN WHICH THE PULSE IS GENERATED BY A SINGLE PHYSICAL IMPACT UPON THE CONCRETE, USUALLY A HAMMER BLOW, AND THE TRANSIT TIME BETWEEN TWO MORE OR LESS ARBITRARILY PLACED PICKUPS IS MEASURED BY SOME ELECTRONIC DEVICE. THESE UNITS DO NOT INCLUDE ANY PROVISION FOR VISUAL OBSERVATION OF THE TEST SIGNALS. IN THE SECOND CATEGORY ARE A NUMBER OF DEVICES WHICH ARE ENTIRELY ELECTRONIC, THE PULSE BEING GENERATED BY THE FIRING OF A THYRATRON AND TRAVELING DIRECTLY FROM ONE PICKUP INTO THE CONCRETE AND, HENCE TO THE SECOND PICKUP. IN THESE UNITS THE REPETITION RATE OF PULSE APPLICATION IS HIGH, AND THE TRANSMITTED AND RECEIVED SIGNALS ARE DISPLAYED UPON A CATHODE-RAY OSCILLOSCOPE WITH PROVISIONS FOR DIRECT MEASUREMENT OF THE TRANSIT TIME. THE THIRD GROUP FALLS SOMEWHERE BETWEEN THESE TWO EXTREMES, WITH THE PULSE APPLIED THROUGH A PHYSICAL BLOW, USUALLY THAT OF A MOTOR-DRIVEN HAMMER REPEATED AT THE RELATIVELY LOW RATE OF A FEW TIMES PER SECOND, AND THE SIGNAL PICKED UP VERY MUCH AS IS THAT GENERATED BY THE FIRST GROUP OF INSTRUMENTS. WITH THESE DEVICES, HOWEVER, THE TRANSMITTED AND RECEIVED SIGNALS ARE PORTRAYED ON AN OSCILLOSCOPE WITH PROVISIONS AVAILABLE FOR MEASUREMENT OF THE TRANSIT TIME OF THE PULSE. ALL THREE TYPES ARE CONSIDERED IN DETAIL. /AUTHOR/
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Supplemental Notes:
- Vol 33, pp 226-242, 11 FIG, 46 REF. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved.
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Authors:
- Whitehurst, E A
- Publication Date: 1954
Media Info
- Media Type: Digital/other
- Monograph Title: Proceedings of the Thirty-Third Annual Meeting of the Highway Research Board, Washington, D.C., January 12-15, 1954
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Serial:
- Highway Research Board Proceedings
- Volume: 33
- Publisher: Highway Research Board
Subject/Index Terms
- TRT Terms: Concrete; Concrete curing; Concrete tests; Cracking; Dynamic modulus of elasticity; Measuring instruments; Pulses; Strength of materials; Ultrasonic tests; Velocity
- Uncontrolled Terms: Concrete cracking; Pulse velocity
- Subject Areas: Highways; Materials;
Filing Info
- Accession Number: 00213964
- Record Type: Publication
- Files: TRIS, TRB
- Created Date: May 22 1972 12:00AM