The role of Non-destructive Testing (NDT) for improving ...

of 60 /60
The role of Non-destructive Testing (NDT) for improving safety and reliability in concrete construction Mohamad Pauzi Ismail, PhD. NDT group manager, Malaysian Nuclear Agency, Bangi, 43000 Kajang. Tel: 019-3800155 Fax:603-89250907 www.nuclearmalaysia.gov.my www.utmr.blogspot.com pauzi @nuclearmalaysia.gov.my

Embed Size (px)

Transcript of The role of Non-destructive Testing (NDT) for improving ...

Introduction to NDT concreteThe role of Non-destructive Testing (NDT) for improving safety and reliability in
concrete construction Mohamad Pauzi Ismail, PhD. NDT group manager, Malaysian Nuclear Agency, Bangi, 43000 Kajang. Tel: 019-3800155 Fax:603-89250907 www.nuclearmalaysia.gov.my www.utmr.blogspot.com pauzi @nuclearmalaysia.gov.my
Bridge failures
Bridge failures
9/8/2014 4International Construction Week 17-19 Sep 2014, PWTC
Periksa semua jejambat -- PM arah Kementerian Kerja Raya laksana segera seluruh negara Oleh HATA WAHARI dan YULPISMAN ASLI (Utusan Online 2006)
KUALA LUMPUR 10 Feb. - Datuk Seri Abdullah Ahmad Badawi mengarahkan Kementerian Kerja Raya memeriksa serta-merta semua struktur jejambat dan lebuh raya bertingkat di seluruh negara. Arahan itu dikeluarkan kepada Menteri Kerja Raya, Datuk Seri S. Samy Vellu yang menemui beliau di pejabatnya di Putrajaya, hari ini. Menurut Perdana Menteri, pemeriksaan tersebut perlu disegerakan dan bukan ditumpukan di ibu negara sahaja. ``Jabatan Kerja Raya (JKR) dan Lembaga Lebuh Raya Malaysia (LLM) perlu terus membuat pemeriksaan yang kerap terhadap jalan-jalan bertingkat kerana jika didapati retak atau rosak akan dapat dibaiki dengan segera. ``Kalau kita terlewat mengetahui kerosakan yang berlaku dan menyebabkan jambatan rosak, runtuh serta ditutup, ini akan menimbulkan banyak masalah kepada rakyat,'' katanya.
9/8/2014 5International Construction Week 17-19 Sep 2014, PWTC
9/8/2014 6International Construction Week 17-19 Sep 2014, PWTC
9/8/2014 7International Construction Week 17-19 Sep 2014, PWTC
Why we need NDT in concrete?
• accident prevention • to reduce costs • to improve product reliability • to determine acceptance to a given requirement • to give information on repair criteria.
9/8/2014 8International Construction Week 17-19 Sep 2014, PWTC
Where Is NDT Used?
• where we need to ensure the serviceability of a specimen
• where we cannot afford the cost of a failure of the specimen because failure would be financially unacceptable or cause harm to us
• exist to prevent injury or death to the human user of the tested item
9/8/2014 9International Construction Week 17-19 Sep 2014, PWTC
When Is NDT Used?
• NDT is used both before, during and after construction
• Using NDT "before or during construction" prevents a substandard material or part from wasting time and increasing scrap production
• Using NDT after to monitor performance after being service.
9/8/2014 10International Construction Week 17-19 Sep 2014, PWTC
Effective NDT
In order to gain the information and obtain valid results, the following is required:
• trained and qualified personnel • a procedure for conducting the test • a system for reporting results • a standard to interpret the results.
9/8/2014 11International Construction Week 17-19 Sep 2014, PWTC
NDT certificate holder
139/8/2014 International Construction Week 17-19 Sep 2014, PWTC
SAMM MS ISO/IEC17025 accreditation
MIBAS MS ISO/IEC17020
• NDT, Nuklear Malaysia
MyPTP MS ISO/IEC 17043
9/8/2014 16International Construction Week 17-19 Sep 2014, PWTC
Non-destructive Testing (NDT) is a test that does not impair the intended performance of the element or member under investigation
• Visual Inspection • Rebound hammer • Rebar locator • Carbonation test • Ultrasonic • Half-cell potential • Windsor probe
• Radiography • Moisture/Density Gauge • Radar • Eddy current • Thermography • Acoustic emission • etc. 20 methods in BS
NDT in Civil & Structural Engineering includes:
What is NDT?
1- Rebound hammer
10- Half-cell Potential
Strength
Items
Inspection Program
Building N/K every 5yr as request
every 10y
every yr (visual)
every year (visual)
Code, standard availability
Items Mechanical constr.
?? x
Building Inspection Flow chart Record
SECOND SURVEY
Record
Crack survey Repair if Grade II
& III and crack not growing
THIRD SURVEY if crack is growing
Water leaking Repair if Grade III & IV
THIRD SURVEY if Grade III & IV
Concrete strength
THIRD SURVEY if Grade II & III
Large Defelection Repair if Grade
III & IV THIRD SURVEY if Grade III & IV
Surface Deterioration
THIRD SURVEY if Grade II & III
Estimate remaining life
Bridge Inspection Flow chart
INVESTIGATION
CHECK ON DESIGN
RECORDS (DATA BANK)
to workmanship, structural serviceability & deterioration
Typical defects in building
Typical defects in bridge
Crack mapping/density
Acceptance criteria (building)
Acceptance criteria (building)  BS811021985
• 3.2.4 Excessive cracking
• 3.2.4.1 Appearance. For members that are visible, cracking should be kept  within reasonable bounds by
• attention to detail. As a guide the calculated maximum crack width should  not exceed 0.3 mm.
• 3.2.4.2 Corrosion. For members in aggressive environments, the calculated  maximum crack widths should
• not exceed 0.3 mm.
• 3.2.4.3 Loss of performance. Where cracking may impair the performance of  the structure,
• e.g. watertightness, limits other than those given in 3.2.4.1 and 3.2.4.2 may  be appropriate.
• For prestressed members, limiting crack widths are specified in section 2 of  BS 81101:1997
9/8/2014 30International Construction Week 17-19 Sep 2014, PWTC
Acceptance criteria (building)  BS811011985
• 2.2.3.4.2 Prestressed concrete
• In the assessment of the likely behaviour of a prestressed  concrete structure or element the amount of flexural  tensile stress determines its class, as follows:
• class 1: no flexural tensile stresses;
• class 2: flexural tensile stresses but no visible cracking;
• class 3: flexural tensile stresses but surface width of cracks  not exceeding 0.1 mm for members in very aggressive  environments (e.g. exposure to sea or moorland water)  and not exceeding 0.2 mm for all other members
9/8/2014 31International Construction Week 17-19 Sep 2014, PWTC
Acceptance criteria (bridge)
BAR LOCATOR
9/8/2014 33International Construction Week 17-19 Sep 2014, PWTC
Ground Penetrating Radar (GPR)
• Propagation  dependent on  dielectric constant  and electrical  conductivity of media
9/8/2014 35International Construction Week 17-19 Sep 2014, PWTC
NEUTRALIZATION/CARBONATION TEST/ pH TEST
A purplered coloration will be  observed in the area highly alkaline  concrete, and no coloration will 
appear in carbonated area  
CARBONATION TEST (cont)
• Test concrete should be treated  immediately after sample has been  cut or broken from concrete member.
• The carbonated part  will show no  colouration. The good part of highly  alkline  redpurple colouration.
• Alternative method: by drilling into  concrete member and drill powder  may be sprayed by the indicator observe change of colouration
9/8/2014 37International Construction Week 17-19 Sep 2014, PWTC
REBOUND HAMMER
• can be correlated with concrete strength
• estimation error ~ 30%
ULTRASONIC METHOD
• Pulse velocity
• Detect void or  honeycombs
• Depth of damage
Ultrasonic Measurements in Concrete
• Frequency used: 25 and 250 kHz, i.e.   wavelengths range from 200 mm to 10 mm
• Possible to test samples thickness of up to  13 m at low frequency
• Measurements usually involve  determination of the speed of sound
9/8/2014 41International Construction Week 17-19 Sep 2014, PWTC
Testing methods
• Through Transmission pulse method
Resonance Equipment
Pulse echo reflection
Ultrasonic tomography
Panel hadapan – Imej tomografi Panel belakang - transduser
Pemeriksaan terowong kereta api Imej tomografi yang dihasilkan
2014, PWTC9/8/2014 46
Flaw Detection in Concrete
• presence of internal defects in a sample of  concrete gives rise to a decrease in  amplitude of the received signal
)( )(
Acceptance criteria
Above 4575 3660 – 4575 3050 – 3660 2135 – 3050 below 2135
Excellent Generally good Questionable
Generally poor Very poor
Penetration Test (Windsor probe)
• This can be directly  correlated to  compressive  strength of concrete.
9/8/2014 50International Construction Week 17-19 Sep 2014, PWTC
Radiography
• Xrays or gammarays penetrates through  concrete samples, and image of change in  thickness or density collected by the  photographic film.
• The variations of intensity detected correspond to  internal structures of the concrete sample.
• Suitable for study on aggregates arrangement,  present of voids, internal cracks, segregation,  honeycombed and reinforcement bar condition  and position.
9/8/2014 51International Construction Week 17-19 Sep 2014, PWTC
Radiation sources
• Iridium, Ir192 (206612 keV) – Half life= 74  days, Output = 0.48 – Penetration: 25mm~250mm concrete
• Cobalt, Co60 (11731333 keV) – Half life= 1925 days, Output =1.30 – Penetration: 125mm~500mm concrete
• Linac/Betatron 8MeV Xrays – penetrate 500mm~1600mm
9/8/2014 52International Construction Week 17-19 Sep 2014, PWTC
Typical Exposure chart
Typical Radiographs from concrete • Radiographic image of 
1200 mm thick  concrete using a 7.5  MeV Betatron and Agfa  Structurix DPS image  plate. The three holes  in the centre have a  diameter of 20 mm and  depth 15, 20 and 40  mm (from top to  bottom)
9/8/2014 54International Construction Week 17-19 Sep 2014, PWTC
Example of radiographic image of void and bar in concrete. SFD: 500mm, concrete thickness: 150mm, source: Ir-192, exposure: 4 Ci-hr, film: Agfa D7
9/8/2014 55International Construction Week 17-19 Sep 2014, PWTC
Advantage and disadvantage of RT
• High energy radiography has been found to be   reliable NDT method for locating prestressed cable  ducts, determine the existence and size of voids in  the grout filler inside the ducts, and also to enable  inspection of the cables themselves. 
• Method has not been fully exploited on site, possibly  because of radiation safety considerations and  possibly because of portability and cost
9/8/2014 56International Construction Week 17-19 Sep 2014, PWTC
Gamma/Neutron Gauge
• Use to check degree of concrete  compaction and moisture content
9/8/2014 57International Construction Week 17-19 Sep 2014, PWTC
IR Thermography
• Application of IR could be either using  passive or active technique
• Passive technique monitor heat  distribution existing in the system whereby  a ‘hot spot’ will be indicated as a possible  defect.
• Active technique monitoring will be  carried out after building heated by sun   
9/8/2014 58International Construction Week 17-19 Sep 2014, PWTC
Typical Thermographs compared to photographs
Cold area
Cold area
CONCLUSION
• NDT has been applied successfully in mechanical  engineering
• In Civil construction NDT is used as detail  investigation as a result of  sign of deterioration  found during visual survey.
• NDT instrument is cheap, simple and portable.
• NDT may replace destructive testing
9/8/2014 60International Construction Week 17-19 Sep 2014, PWTC
The role of Non-destructive Testing (NDT) for improving safety and reliability in concrete construction
Building failures
Bridge failures
Bridge failures
Where Is NDT Used?
When Is NDT Used?
SAMM MS ISO/IEC17025 accreditation
MyPTP MS ISO/IEC 17043
Non-destructive Testing (NDT) is a test that does not impair the intended performance of the element or member under investiga
Inspection Program
Typical Radiographs from concrete
Example of radiographic image of void and bar in concrete. SFD: 500mm, concrete thickness: 150mm, source: Ir-192, exposure: 4
Advantage and disadvantage of RT
Gamma/Neutron Gauge
IR Thermography
CONCLUSION