A Seminar Report on Significance of Non-Destructive Testing of Concrete.

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REPOR-:f

SIGNIFICANCE OF NON

- DESTRUCTIVE

TESTING OF CONCRETE

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AP;'UEC fv1ECHAIliCSDEPARTMENT /"IV ~IVNAl.

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ENf:INEER,I'4!';'

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ACKNOWLEDGEMENT : ta,ke thlS "'pport mi ty

to express m;' sincere tha,nks a,nd deep sense of

grati tude to my guide Hiss Vaishal1 Patel Department of Applied tlechanics, Sardar "alla,bhbhai Regional College of EngHreering &: Technology, Surat "nthout whose guidance and encourageroent this seminar mould not have been fulfilled.

Ja,ln Niktlll R. BE. IV CI"IL"

CONTENT 1.0 UITRODUCTION 2, u t-[E71-iODS FORNIT OF CONCRETE L.,. SUPFACEHAFiDNESSHETHOD

2.1.1

INDENTATIONMETHOD

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REBOI~1D METHOD

2.: IBR1..TION OR D't1lliIIC :.2.1

METHOD

RESONANT FREQUENCY METHOD

2.2,2 PULSEvELOSIT:METHOt iA

SONICPULSEVELOCIT, METHOD

B \ ULTRASONICPU:"SEVELOC:""',HETHOD 2.3 RADIO-ACTI''E ORNUCLE,a.R !lETHO:

2,4. J. HAGNETI: HETHODS

2. it.: :~IELECTRJ." liEA.SURE11Et;;'S

2.4.3 ELECTRICAL RESISTI'IT: TES: 2.5 n'THERETHOD;;:; 2.5 1 PENETRa.TION METHOD

2.5.2 PULLOUtMETrlOD

2.5.3 ACOUSTI~ EMISSlv~TES: 2.6 COHBINEDMETHODS 2,'" CONCLUSION REFERENCES.

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_S.EMINAR '99 ;

1.0

INTRODUCTION

Concrete is a composite material made from cement, fine aggregate, coarse aggregate and water. A large number of variables are involved in the production of concrete that affect the properties of the resulting concrete. It is important to know the properties of concrete in its final form in the structure proper. The conventional method of ascertaining the quality of concrete is to test a number of control specimens. This, at best, can give the potential quality of concrete as mixed. It is desirable to have some method of testing the concrete in the structure without damaging it. This is possible with the help of Non-Destructive Testing (NDT). NDT can be defined as examining material or products to determine their fitness for certain purpose or functional requirement without impairing their desirable properties.

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NDT methods of testing concrete can not be expected to yield absolute values of strength. Therefore these methods attempt to measure some other property of concrete from which an estimate of its strength. Its durability and its elastic parameters is obtained. NDT is a quality assurance managementtool which can give impressive results when used correctly. It requires an understanding of the various methods available, their capabilities and limitations. knowledge of the relevant standards and specifications for performing the tests. This paper discuss various NDT methods which are most commonly used in the testing of concrete. These methods include Surface methods, Vibration or Dynamic methods, Radio-active or Nuclear methods, Electro-Magnetic methods and some other methods. 2.0

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METHODS FOR NOT OF CONCRETE The various techniques that can be used for NDT of concrete are listed below : SURFACE METHODS: (I ) Hardness: (a) Indentation (b) Rebound (ii) Water absorption VIBRATION OR DYNAMIC METHODS: (i) Resonancefrequency method (ii) Pulsevelocity method (a) Sonic (b) Ultrasonic RADIOACTIVE METHODS: (i) x-ray or gamma -ray transmission (ii) gamma-ray back scatter (HI, Neutron moderation & scattering (iV)

ActiVation analysis

Applied Mechanics Department S. V. Regional

College of Engineering

& Technology,

SURA T.

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Concrete

Impact sprong

surface

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Plunger

. RE30UNDHAMMER

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ELECTROMAGNETIC METHODS:

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(j) Magnetic methods

(ii) For Dielectric properties (iii) Conductivity! Resistivity (!i Penetration Test (Ii) Pull out (iii) Cutoff (iv) Acoustic emission

OTHER METHODS:

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COMBINEDMETHODS.

2.1

SURFACE HARDNESS METHOD 2.1.1 INDENTATION METHOD

In this method a certain amount of force is applied to the surface of the material to be tested through a suitable indenter forming a permanent impression. The size of this mdentation is measured and that indicates the hardness. Smaller the indentation, harder the material using the same indenter and the same force. The dlstnbutlon of stress and strain around the actuai indentation-the contact zone-have been analysed in detail indicating that a definite thickness below the surface is affected, about 2 times the size of the indentation. A calibration curve can be established for a material like concrete relating the siZe of indentation and the strength of concrete. T'"

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lie Inden.er use.d are (Ii t

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t t mg pISt 0,I v ~!,,~ums.es (II~ FranK spring hammer (lit) Elnbeck pendulum hammer \1\1"1"."

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REBOUND METHOD

The S\IVISSEngineer Ernst Schmidt developed rebound hammer in 1940.

Rebouna hammer consists of a spring-controlled hammer mass that slides on a plunger with a tubular rousing.The plunger retracts against a spring when passed aga'"st the concrete surface and this spring is automatically released when fully tensioned causing t'1e I1arnmern"tassto impact against the concrete through the plunger When sprin~ controllec.mass rebounds, it takes with it a rider which slides along 2 scale and IS risible.. IIou~... a sMa:! window in the side of the casing. The '"'cer ca- be "eld 11pos'''OJ' G' ..,e sr-ale tJy depressHlg the locking button. The

olunger IS "'''e