ISSN: 0149-6123
CODEN: CCAGPD
Page Count: 6

Use of Ultrasonic Pulse Velocity for Fracture Testing of Cemented Materials
Alexander, MG
Senior lecturer, University of the Witwatersrand,

Abstract

The paper describes the use of the ultrasonic pulse velocity technique to measure two important features of fracture in notched concrete beams: the extent of the zone of microcracking that develops ahead of the notch or crack, and the depth of the main (or stress-free) crack. Beams of 100 mm in width and ranging from 100 to 500 mm in depth were tested, and ultrasonic pulses were transmitted longitudinally through the beams at various elevations. Ultrasonic readings taken at elevations above or below the visible crack tip were found to be sensitive to the development of the microcracked zone or to main crack growth, respectively. Based on pulse transit time measurements, the average depth of the microcracked zone was about 44% of the residual beam depth, taking all the beam sizes together. Crack depths estimated from pulse transit times were found to agree with visible crack depths to less than 10% on average.

Keywords:
concrete, ultrasonic testing, microcracking, cracking, fracture

Paper ID: CCA10025J
DOI: 10.1520/CCA10025J
ASTM International is a member of CrossRef.