ELSEVIER PII: S0963-8695(97)00024-8

NDT&E International, Vol. 30, No. 4, pp. 255-266, 1997 Elsevier Science Ltd

Printed in Great Britain

-ND T abstracts N D T A b s t r a c t s a r e c o m p i l e d b y A E A T e c h n o l o g y N a t i o n a l N D T C e n t r e , H a r w e l l , O x o n , O X 1 1 0 R A , U K . T h e e n t r i e s a r e d r a w n f r o m o v e r 500 B r i t i s h a n d I n t e r n a t i o n a l p u b l i c a t i o n s . E a c h i s sue c o n c e n t r a t e s o n o n e o r t w o s u b j e c t a reas .

The u l t rasonic test ing of concrete

62585 Lin, Y.C.; Su, W.C. Use of s t ress waves for determining the depth of surface- open ing cracks in concrete s t ruc tu res ACI Materials Journal, Vol. 93, No. 5, pp. 494-505 (1996)

The objective was to determine the depth of surface-opening (visible) cracks in concrete structures with the use of stress waves so that a safety evaluation of such cracked structures can be subsequently performed. In addition to the time-domain analysis, frequency analysis can be used to ascertain whether the surface-opening crack under testing is approximately perpendicular to the surface.

62351 lsmail, M.P.; Yuso]; K.M.; Abrahim, A.N. A combined u l t rason ic method on the estimation of compress ive concre te strength Insight, Vol. 38, No. I l, pp. 781-785 (Nov. 1996)

This paper introduces a method which combines the ultrasonic pressure wave velocity and relative amplitude that can reduce error to + 5%. The relative amplitude is basically an attenuation method which measures the ratio of the pressure and the shear wave amplitudes.

61470 Ismail, M.P.; YusoJ; K.M.; Ibrahim, A.N. Propagation of Rayleigh waves in concre te Insight, Vol. 38, No. 5, pp. 338-340 (May 1996)

The conventional ultrasonic method of checking surface properties of concrete is subject to large errors due to low signal amplitude generated by normal pressure wave transducers. This paper illustrates a series of measurements using an ultrasonic goniometer, on mortar, concrete and rock samples. A 2.25 MHz 10 mm-diameter immersion transducer was used to propagate Rayleigh waves in a sample surface by a corner reflection method. The experimental results show a significant change in velocity and amplitude of the Rayleigh wave. with different concrete quality. This means that it is possible to use a pure Rayleigh wave to check the quality of concrete surfaces or sub- surfaces, as a better alternative to the conventional method.

61072 Jalinoos, F.; Olson, L.D.; Aouad, M.F.; Balch, A.H. Acoust ic t o m o g r a p h y for qual i ta t ive nondes t ruc t ive evaluat ion (QNDE) of s t ruc tu ra l concre te using a new ul t rasonic scanner source Review of Progress in Quantitative Nondestructive Evaluation, Vol. 14B. Proceedings of the 21st Symposium on Quantitative Nondestructive Evaluation, Snowmass Village, Colorado (United States), 31 Jul. - 5 Aug. 1994, pp. 2177-2184. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1995) ISBN 0306450623.

A major emphasis in concrete NDT is the evaluation of concrete integrity and the detection of defects such as voids, honeycomb, cracking, and delamination in concrete. The conventional UPV tests (ASTM Standard C597-83) may indicate the presence of a flaw, but are limited in determining the depth (but not the lateral definition) of the flaw. The scanner system was developed specifically to increase the data acquisition speed for the Ultrasonic Pulse Velocity (UPV) testing method and to provide information on the closely-spaced grid that is required for imaging purposes.

61071 Peterson, M.L.; Landis, E.; Achenbach, J.D. Ult rasonic eva lua t ion of damage in concrete br idge deck pavements Review of Progress in Quantitative Nondestructive Evaluation, Vol. 14B. Proceedings of the 21st Symposium on Quantitative Nondestructive Evaluation, Snowmass Village, Colorado (United States), 31 Jul. - 5 Aug. 1994, pp. 2169-2176. Edited by D.O. Thompson and D.E. Chimenti. Plenum Press (1995) ISBN 0306450623.

Interest in repair, maintenance and characterization of infrastructure in the United States has reached unprecedented highs in recent years. The interest in this areas is motivated by the aging and associated degradation of our built environment. The materials often show a large variation in their properties between samples as well as a large spatial variation in properties in a single sample. Perhaps the most important material, concrete, may also be the most variable material used in infrastructure.

60831 Thomas, M.D.A. Ult rasound tomography applied to AAR-affected concrete s t ruc tu res Proceedings of the 2nd International Conference on Alkali- Aggregate Reactions in Hydroelectric Plants and Dams, Chattanooga, TN (United States), 22-27 Oct. 1995, pp. 359-372. Acres International Corporation (1995)

This paper discusses the potential application of ultrasound tomography and scientific visualization for evaluating the internal condition of massive concrete structures affected by AAR and other deterioration processes. If sufficient measurements are made to form a network of velocities across a single cross-section, tomographic methods can he applied to produce a two-dimensional image of the spatial distribution of velocity data within the section. Results are presented from a preliminary study carried out to assess the potential application of this technique for evaluating the internal condition of large concrete elements.

60639 Nazarian, S. Detection of deterioration within and beneath concrete pavements with sonic and ultrasonic surface waves Proceedings of Nondestructive Evaluation of Civil Structures and Materials Conference, Boulder, Colorado (United States), 15-17 Oct. 1990. pp. 371-391. PB94-121720. Edited by B.A. Suprenant, S. Sture, J.L. Noland and M.P. Schuller. National Technical Information Service (1990)

The effectiveness of sonic and ultrasonic surface waves as a quality control tool, as a diagnostic tool and as an inspection tool is demonstrated. The paper basically summarizes more than ten years of research and development in the use of surface waves in pavement maintenance and pavement evaluation. More importantly, recent improvements to the techniques for rapid field implementation are also discussed.

60638 Sahnis, G.M.; Kelishami, R.; Millstein, L. Delamination detection in concrete bridge decks using non- destructive test method Proceedings of Nondestructive Evaluation of Civil Structures and Materials Conference, Boulder, Colorado (United States), 15-17 Oct. 1990. pp. 371-391. PB94--121720. Edited by B.A. Suprenant, S. Sture, J.L. Noland and M.P. Schuller. National Technical Information Service (1990)

Experiments were performed on different types of concrete using Ultrasonic Testing Equipment with the main objective of detecting delamination within the concrete. Four batches of concrete slabs were east each containing six 12 x 12 x 3 inch square specimens. The specimens included one control specimen without delarnination and the rest with delamination provided with a thin styrofoam board. In addition to the detection of delamination, the static and dynamic moduli of elasticity were evaluated with the present method.

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