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*WCNDT '96 - New Delhi *Table of Contents

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NON-DESTRUCTIVE TESTING OF CONCRETE AND MASONRY DAMS USINGULTRASONIC PULSE VELOCITY TECHNIQUE: CASE HISTORIES

B. Suri, N. Chandrasekaran, G. K. Vijh, A. K. SthapakCentral Soil & Materials Research Station, New Delhi------------------------------------------------------------------------

/Keywords: Ultrasonic, pulse velocity, hydraulic structures,quantitative assessment, NDT methods progressive distress /

*ABSTRACT*

Premature or progressive distress in concrete and masonry dams canoccur due to various causes such as improper quality control duringconstruction, expansion due to alkali-aggregate reaction, corrosionof reinforcement, non-homogeneity of concrete, development of cracksdue to shrinkage and/or thermal stresses, leaching of lime frommasonry mortar, aging etc. For evaluating the extent of distress insuch structures and identification of probable causes ofdeterioration, an effective and interpretable non-destructivetechnique (NDT) needs to be employed.

A number of NDT methods have been evolved during the past few

decades. But the ultrasonic pulse velocity method, due to theversatility of its application, easy interpretability, independenceof the test results on the shape and size of the specimen tested andease of deployment in the field, is widely used for non-destructivetesting of hydraulic structures. However, the precise interpretationof data obtained from this technique and quantitative assessment ofthe condition of the structure require vast experience and expertise.

The Central Soil & Materials Research Station, New Delhi has, in thepast, tested a number of concrete and masonry structures suspectedto be distressed due to various causes such as alkali aggregatereaction, sulphate attack, excessive flood flows, defective quality

control during construction and aging etc.

The Paper covers the details of the ultrasonic pulse velocitytechnique used for assessing the general condition of thestructures, determination of depth of cracks, assessment ofprogressive deterioration or otherwise with time, evaluation of therehabilitation measures and the quality of newly built/rehabilitatedstructures etc. Eight very important case histories involvingversatile applications of the ultrasonic pulse velocity method areincluded. The ultrasonic pulse velocity data obtained for concreteand masonry structures from these investigations will provide usefulinformation and guidance for proper interpretation and assessment ofthe quality of similar structures.

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------------------------------------------------------------------------*Publication Source:* Trends in NDE Science & Technology; Proceedings ofthe 14th World Conference on Non-Destructive Testing, New Delhi, 8-13December 1996.*full paper not received **Publisher:* Ashgate Publishing Company ------------------------------------------------------------------------

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