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NDT TESTING TIPS FROM NDTECH - NEWSLETTER #16 - March 2000

This issue of the Newsletter includes:

1. Book Review

2. NDT Abstracts

3. Monitoring of Structural Integrity:SIMoNET

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The NDTech Newsletter is published periodically by NDTech, a consulting firm offering nondestructive

testing, services, and instruments. This newsletter is distributed by email and covers brief descriptions of

some useful but less publicized radiographic, ultrasonic, penetrant, magnetic particle, and other NDT

methods. You will automatically receive the newsletter, at no cost. If you wish to be removed from the

NDTech Newsletter, simply reply with "Remove" as the subject.

To find out more about NDTech and its nondestructive testing consulting services and instrumentation,

visit the NDTech website at http://www.ndtech.net/

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1. Book Review

Nondestructive Testing Handbook, Third Edition, Volume 2,

Liquid Penetrant Testing

Editor, Patrick O. Moore, Technical Editor, Noel A. Tracy

This new edition replaces the Second Edition published in 1982 and includes new and updated

information on what is one of the oldest and most widely used nondestructive testing (NDT) methods.

This handbook, like its predecessors, should prove to be the definitive handbook for liquid penetrant

testing.

The new handbook contains information on applications of liquid penetrants such as filtered particle

inspection of aerospace composites and quality control of down-hole oil tubular assemblies. A new section

on the probability of detection using the method has been added, and the new regulations on

chlorofluorocarbon fluids are considered throughout the text.

Designed to assist the NDT professional practitioner, the Third Edition includes references to the current

standards related to liquid penetrant testing. And for those with a more casual interest in NDT, the

handbook features a comprehensive glossary, hundreds of illustrations, and a comprehensive

bibliography.

With thousands of copies in print, ASNT's Nondestructive Handbook series serves as the defininitive

treatment of NDT technology, with each major method given its own volume. Featuring a new design,

the third edition updates and expands the information found in the second edition. This volume includes

the folowing topics: Role of Nondestructive Testing;Management of Liquid Penetrant Testing;Personnel

Qualification for Liquid Penetrant Testing;History of Liquid Penetrant Testing;Measurement

Units;Principles of Liquid Penetrant Testing;Characteristics of Liquid Penetrants and Processing

Materials;Care and Maintenance of Materials for Liquid Penetrant Testing;and Interpretation of Liquid

Penetrant Testing Indications.

The handbook was published in September 1999 by the American Society for Nondestructive Testing

(ASNT). It is priced at $181.25 worldwide, $135.00 for ASNT members. This book can be order at

http://www.asnt.org.

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2. NDT Abstracts

Use of stress waves for determining the depth of surface-opening cracks in concrete

structures-Lin,Y.C.;Su,W.C.

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.

Ultrasonic evaluation of damage in concrete bridge deck

pavements-Peterson,M.L.;Landis,E.;Achenbach,J.D.

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 these areas is motivated by the aging and associated

degradation of our built enviroment. 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.

Detection of deterioration within and beneath concrete pavements with sonic and ultrasonic

surface waves-Nazarian, S.

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.

Delamination detection in concrete bridge decks using non-destructive test

method-Sahnis,G.M.;Kelishami, R.;Millstein,L.

Proceedings of Nondestructive Evaluation of Civil Structures and Materials Conference, Boulder

Colorado (United Stated), 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 cast

each containing six 12x12x3 inch square specimens. The specimens included one control specimen

without delamination 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.

Inspection of concrete by ultrasonic pulse-echo-technique

-Hillger,W.

6th European Conference on Non destructive Testing, Nice (France), 24-28 Oct. 1994. Vol. 2, pp.

1159-1163. ECNDT (1994).

This article reports the investigations in order to applicate ultrasonic imaging of defects in concrete and

other mineral building materials. The high specific inhomogeneity of this material requires extremely low

test frequencies in order to get ultrasonic waves which wavelengths are greater than the partial size. In

order to get best results optimisations of pulse parameters on the transmitter side and on the reciever side

were necessary. A new ultrasonic imaging system NFUS 2300 has been developed for this special

requirements. The high sound attenuation and the divergence of the probe is compensated by a

programmable DAC with any function up to 60dB dynamic. The system provides imaging in

A-,B-,Bt-,C-andD-scans with high validity of defects in concrete up to a thickness of 1m.

Impact-echo for flaw detection in concrete highway structures-Poston, R.W.

Structural Materials Technology, Atlantic City, New Jersey (United States), 23-25 Feb. 1994. pp.

231-235. Edited by R.J. Scancella and M.E. Callahan. Technomic Publishing Co., Inc. (1994) ISBN

1-56676-141-7.

This paper will briefly summarize background information relevant to flaw detection using the

impact-echo method. This will be followed by several case studies of the use of the impact-echo method

for concrete highway structures. With the development and commerical availability of a field instrument,

the method is now being used in concrete highway structures. The author has succesfully used

impact-echo for detecting flaws in bridge piers, voids in grouted post-tensioned concrete bridge girders,

the extent of web delamination in a pier segment of a precast segmental externally post-tensioned

box-girder bridge, and for determining concrete pavement thickness.

Nondestructive testing of older concrete bridge:a case history of the SEPTA Manayunk

bridge-Sack,D.A.;Olson,L.D.;Kline,T.R.;Yates,G.A.

9th Annual International Bridge Conference, Pittsburgh, Pennsylvania (United States), 15-17 Jun. 1992.

pp. 405-413. Engineers Society of Western Pennsylvania (1992).

Included in this paper is an overview of the Nondestructive Evaluation (NDE) program carried out on the

bridge, and a summary of the results of this program. Also included in this presentation are detailed

descriptions of the NDE methods used in the evaluation. These include the Ultrasonic Pulse Velocity

(UPV) and Impact Echo (IE) methods. The UPV method was used on the relatively thin walls interior to

the arch where access was available on both sides, while the IE method was used on these as well as on

decks, abutments, and other massive concrete structural members.

Nondestructive strength assessment of concrete-based structures-Stewart, A.H.;Goodman, J.R.

Engineering Data Management, Inc. Fort Collins, Colorado (United States), PB94-145851/GAR, 80pp.

(Jul. 1987)

The research was directed at evaluating the feasibility of using a sonic wave nondestructive evaluation

(NDE) method to provide cost-efficent, reliable determination of the compression strength of individual

concrete members. It involved:1)collection of NDE data from concrete cylinders in the

laboratory;2)development of models to predict the compression strength of the cylinders, and 3)

evaluation of the ability of the developed models to predict concrete strength in comparison to current

strength prediction techniques. The standard error of estimate (SEE) was used to define te reliability of

the NDE models. The resulting SEEs for the concrete cylinders are 230psi for the pendelum-based NDE

and 232psi for the impulse hammer-based NDE. The results have verified the validity of the sonic wave

spectral analysis NDE approach.

Advanced NDT methods for concrete structures-Sack,D.A;Olson,L.D.

International Conference on Nondestructive Testing of Concrete in the Infrastructure, Dearborn,

Michigan (United Stated), 9-11 Jun. 1993. pp.353-369. Society for Experimental Mechanics, Inc. (1993)

ISBN 10912053429.

This paper presents several advances in methods and equipment for sonic and ultrasonic Nondestructive

Testing (NDT) of concrete structures. The advances include the use of the Spectral Analysis of Surface

Waves (SASW) method in the NDT of concrete. This method allows the determination of the shear wave

velocity profile versus depth for any layered system and is particularly applicable to testing pavements,

slabs, tunnels, shaft liners, and massive concrete structures. Also discussed is the development of

high-speed scanning technology for the performance of a number of NDT methods which have

traditionally been performed on a point-by-point basis. Test data is presented to illustrate the applications

of the scanner to Ultrasonic Pulse Velocity, Impact Echo, and SASW methods.

Strength evaluation of high-strength concrete by ultrasonic pulse velocity method-Ravindrarajah,

R.S.

Non-Destructive Testing-Australia, Vol. 29, No. 1, pp. 6-9 (Jan.-Feb. 1992)

Nondestructive testing of compressive strength in concrete structures offer several advantages to civil

engineers, economy, speed and minimal damage to the structure under test. Tests work by measuring

some property of concrete of known correlation to compressive strength. The study reported here aims to

apply ultrasonic testing using the pulse velocity method to high-strength concrete. The parameters studied

include type of cement, the effect of silica fume, the age of the concrete and its cure condition. The paste

efficiency principle is also studied. The known correlation between compressive strength and pulse

velocity for water-cured concrete is used successfully, together with the paste efficiency concept, to

assess concrete quality in certain structures from a pulse velocity survey.

Nondestructive evaluation of concrete with impact-echo and pulse-velocity

techniques-Limaye,H.S.;Krause,R.J.

Materials Evaluation, Vol. 49, No. 10, pp. 1312-1315 (Oct. 1991)

The paper describes the applications of two nondestructive techniques, impact echo and pulse velocity, to

evaluate the condition of concrete structures. The power plant case histories describe the evaluation of a

concrete foundation, a tunnel slab, and turbine pedestal columns. In the impact-echo method, the

response of a concrete structure to mechanical impact is monitored and analyzed. The impact induces

longitudinal, shear and surface waves that reflect off internal discontinuities as well as the backs and sides

of the concrete members. These reflections, or echoes, can be analyzed with a fat-Fourier transform

(FFT) analyzer to determine the condition of the concrete. The pulse-velocity method involves

measurement of transit time of an acoustic wave through a concrete structure. Significant changes in

transit time are associated with the internal makeup of the structure. This method can be used to

determine uniformity of concrete and to detect internal faults such as cracks, voids, or honeycombing.

Flaw detection in concrete using the impact-echo method-Carino, N.J.;Sansalone, M.

Bridge Evaluation, Repair and Rehabilitation. Edited by A.S. Nowak. pp. 101-118. Kluwer Academic

Publishers (1990).

A technique called the impact-echo method has been developed for flaw detection in concrete. This paper

discusses the theoretical basis of the method and gives representative examples of the results of analytical

and experimental studies. A procedure called spectral peak plotting is described which simplifies

interpretation of data from scans across a structure. By using this procedure a profile view of the interior

of the test object can be constructed.

Ultrasonic testing to identify alkali-silica reaction in concrete-Bungey, J.H.

British Journal of Nondestructive Testing, Vol. 33, No. 5, pp. 227-231. (May 1991)

Deterioration of concrete structures in the United Kingdom due to alkali-silica reactions has caused

considerable concern. This paper describes a pilot programme to consider the feasibility of using

ultrasonic testing to assess and monitor the condition of concrete in buildings and structures known to be

suffering from this so called "Concrete Cancer". The presence of moisture while the concrete is in service

shown to effect the degree of expansion and cracking caused by alkali-silica reactions. Pulse velocity and

attenuation methods were both successful for expansions up to 0.3% but access to rear faces remains a

problem with ultrasonic testing.

Advanced pulse echo method for ultrasonic testing of concrete-Krause, M.;Wiggenhauser,H.;Wilsch,

G.

Non-Destructive Testing in Civil Engineering, Liverpool (United Kingdom), 14-16 April 1993. Vol. 2, pp.

821-827. Edited by J.H. Bungey. The British Institute of NDT (1993)

The analysis of data collected with Ultrasonic Pulse Echo (UPSE) experiments on concrete layers with a

thickness of 200 to 400 mm is presented. A phase-correlated overlay of the US-signal depending on the

distance of recieving and transmitting transducer during the experiment gives a constructive superposition

of the reflection signal, whereas the surface waves are suppressed by the random average. This analysis

can be done for varying estimates of the thickness of the specimen and gives the highest correlation for

the actual thickness.

Strength evaluation of high-strength concrete by ultrasonic pulse velocity method-Sri

Ravindrarajah, R.

Australian Institute of Non-Destructive Testing National Conference, Melbourne (Australia), 19-21

August 1991. 10pp. AINDT (1991)

This paper reports the results of an investigation into the use of ultrasonic testing to high-strength concrete

having the 28 days compressive cube strength of about 80 MPa. The parameters studied include cement

type, effect of silica fume, age, and curing conditions. Normal portland cement (Type A) and normal

blastfurnace portland cement (Type SA) were used in the producing the high-strength concrete mixes.

The results confirm that the compressive strength-pulse velocity relationship from an early age of 5 hours,

can be represented by an exponential curve. Air-curing is identified as the major factor in reducing the

pulse-velocity of high-strength concrete at any age, due to strength loss and moisture loss. The use of

silica fume in the concrete mixes improved the pulse velocity values through the pore filling and

pozzolanic effects of silica fume. The paste efficiency principle based on the pulse velocity difference

between water-cured and air-cured test specimens can be used to evaluate the in-situ concrete strength.

The results showed that the k-value relating the pulse velocity difference and the ratio of water-cured

strength to air-cured (in-situ) strength is 0.010 for high-strength concrete compared to 0.019 for

medium-strength concrete.

Damage detection in concrete elements with surface wave measurements-Bowen, B.R.

Dissertation Abstracts International, Vol. 53, No. 4, p. 1966-B(October 1992)(DA 9225529)

The objective of this research was to assess the ability of surface waves measurements and the SASW

technique to detect crack damage in beam and column elements. The damage was detected by a change

in the surface wave dispersion curve (phase velocity vs. frequency) between undamaged and damaged

states. To calculate the dispersion curve, the SASW (Spectral Analysis of Surface Waves) technique was

used with response records from two locations. Finite element analysis was used to to analytically

generate the response records. Experimentally, acceleration measurements were taken. Results shows that

the SASW method is one potential method to detect cracks.

Evaluation of compressive strength for high-strength concrete by pulse velocity method-Sri

Ravindrarajah, R.

Nondestructive Testing of Concrete Elements and Structures, San Antonio, Texas (United States), 13-15

April 1992, pp. 115-126. Edited by F. Ansari and S. Sture. ASCE (1992)

Development of compressive strength and pulse velocity for high-strength concrete from the age of 5

houre are studied in relation to blast-furnace slag cement and silica fume are used individually or in

combination. Results show that: a) silice fume in concrete increases the pulse velocity; b) pulse velocity

and strength are lower for air-cured concrete than for water-cured concrete; and c) the relationship

between strength and pulse velocity is given by an exponential curve which is less influenced by curing or

cementitious material types. Evaluation of in-situ concrete strength based on paste efficiency concept is

examined.

Evaluation of concrete bridges by impact-echo-Ghorbanpoor, A.;Virmani, Y.P.; Fatemi, G.R.

Nondestructive Testing of Concrete Elements and Structures, San Antonio, Texas (United States), 13-15

April 1992, pp. 94-103. Edited by F. Ansari and S. Sture. ASCE (1992)

This study has examined the application and further development of a non-destructive evaluation

technique, the Impact-Echo for determination of location and extent of voids in the ducts of

post-tensioned bridge structural members. Theoretical laboratory, and field studies have been performed

and it has been demonstrated that it is possible to detect, with high reliability, the location and extent of

voids in the post-tensioning ducts of concrete structures. It was found that information corresponding to

the location of voids within concrete members may readily be obtained by examining the wave reflection

frequency values, from an induced impact at the surface of the member, due to the wave incidents at the

free boundaries of these voids.

Sonic NDE of structural concrete-Olson, L.D.

Nondestructive Testing of Concrete Elements and Structures, San Antonio, Texas (United States), 13-15

April 1992, pp. 70-81. Edited by F. Ansari and S. Sture. ASCE (1992)

Case histories are presented to illustrate applications of nondestructive evaluation (NDE) methods that use

stress waves to characterize the conditions of concrete construction. The case histories discuss the

following NDE methods and applications; 1. Impact Echo to evaluate cracking in a 1923 thin-arch

concrete dam on the downstream face; 2. Impact Echo to investigate honeycomb and void conditions,

and to provide quality assurance of repairs to a box girder bridge; and 3. Ultrasonic Pusle Velocity to

define the severity of cracking damage in pre-cast bridge segments and for quality assurance of epoxy

injection repairs. NDE methods accurately defined the extent and nature of sound and defective concrete

conditions.

Recent developments in inspection techniques for corrosion damaged concrete structures-John,

G.;Hladky,K.;Gaydecki,P.;Dawson, J.

Corrosion Forms and Control for Infrastructure. Edited by V. Chaker, pp. 246-257. ASTM. STP

1137(1992)

Improved procedures for inspecting both reinforced concrete and prestressed concrete structures, with

regard to determination of the embedded steel components are discussed. Prototype ultrasonic procedures

recently developed to determine the condition of prestressed pretensioned tendons in concrete will be

discussed. The application of electrochemical surface mounted systems for estimating the rate of

corrosion of reinforcing steel and other embedded steel components in large concrete structures will also

be described. In particular, the ability to obtain rate of corrosion data over the concrete surface and

presenting it as iso-corrosion rate contours will be highlighted.

Setting time and strength of concrete using the impact-echo method-Pessiki, S.P.;Carino, N.J.

ACI Materials Journal, Vol. 85, No. 5, pp. 389-399 (Sept.-Oct. 1988)

Tests were performed to evaluate the feasibility of using the impact-echo method to determine setting

time and to monitor strength development of concrete. In the impact-echo method, the test object is

subjected to point impact and the surface displacement is monitored at a point adjacent to the impact.

From the measure displacement waveform and the thickness of the object, the P-wave velocity is

determined. Changes in the P-wave velocity with time reveal information about the development of

mechanical properties as the concrete matures. Tests were performed to examine the relationship between

P-wave velocity, as determined by the impact-echo method, and the compressive strength of concrete. It

is concluded that the impact-echo method is a promising nondestructive technique.

The above NDT Abstracts are available in the USA from the National Technical Information Service,

US Department of Commerce, Springfield, Virginia 22151, USA.

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3. Monitoring of Structural Integrity:SIMoNET

Structures are designed to survive for a given service life. However, due to enviromental, manufacturing,

material and design uncertainties the strength may be different to that anticipated and may degrade to

point where failure becomes possible. Failure of structures is totally unacceptable, leading to loss of life,

enviromental damage and it can be very costly.

Designers, Consultants, Asset Owners have many analytical methods at their disposal to ensure structural

integrity. Most of these require in-service inspection to provide data on the current state of the structure.

It is now becoming possible to monitor continuously the state of the structure and if necessary do this

monitoring remotely. This is referred to as Structural Integrity Monitoring (SIM) and, in principle, allows

the responsible person to interrogate a structure to determine its current condition. This would then allow

the estimation of the probability of failure and remedial action if necessary.

To aid the development of the emerging activity known as Structural Integrity Monitoring a new network

has been established known as SIMoNET a(Structural Integrity Monitoring Network). This is a free

access network for the first three years (due to support from EPSRC) that will hopefully remain free

thereafter with Industrial Sponsor support.

SIMoNET is establishing a multidisciplinary group for the exchange of information and experience on

SIM. The aim is to link Industry and University in order to solve problems of common interest and

exchange information on SIM.

SIMoNET will identify the latest available technology, experience in use, and methods of retrieving and

interpreting data. It will work to encourage the harmonisation of data storage abd retrieval by identifying

incompatibility within systems. SIMoNET will attempt to provide general guidelines for the practice and

application of structural monitoring and to identify priorities for further development.

This will be done by developing a website so that information can be made available to a wide audience.

Seminars will also be arranged to allow discussion and the first meeting, scheduled for 30 March 2000,

will be on 'SIM for Offshore Structures, Bridges, Transport and Process Plant.'

SIMoNET will address the problems of structures in the Oil and Gas Industry, Industrial Process Plant,

Bridges, Ships, Nuclear, Rail and Civil Engineering. It has coordinators at UCl and Cranfield, and a

Steering Group drawn from HSE, Ove Arup, BP, British Gas, TWI, Railtrack, UCL, Cranfield and

Independent Consultants.

SIMoNET can be found at http://www.simonet.org

Registration is free.

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Copyright © 1999 NDTech.

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