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 Building failures 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 2 Bridge failures 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 3 Bridge failures 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 4 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 International Construction Week 17-19 Sep 2014, PWTC 5 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 6 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 7 Why we need NDT in concrete? • • • • • 9/8/2014 accident prevention to reduce costs to improve product reliability to determine acceptance to a given requirement to give information on repair criteria. International Construction Week 17-19 Sep 2014, PWTC 8 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 International Construction Week 17-19 Sep 2014, PWTC 9 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 International Construction Week 17-19 Sep 2014, PWTC 10 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 International Construction Week 17-19 Sep 2014, PWTC 11 NDT certificate holder • www.endt.gov.my • https://www.asnt.org/certificant • http://www.bindt.org/Certification/PCN_Certi fication_Verification 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 12 ASNT Central Certification Program (ACCP) level III 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 13 SAMM MS ISO/IEC17025 accreditation • NDT, SIRIM • AIROD • SME 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 14 MIBAS MS ISO/IEC17020 • • • • • NDT, Nuklear Malaysia Lott inspection Petrotechnical Inspection Careion NDE Consultancy 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 15 MyPTP MS ISO/IEC 17043 • Nuklear Malaysia (to be applied) 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 16 What is NDT? Non-destructive Testing (NDT) is a test that does not impair the intended performance of the element or member under investigation NDT in Civil & Structural Engineering includes: • • • • • • • Visual Inspection Rebound hammer Rebar locator Carbonation test Ultrasonic Half-cell potential Windsor probe 9/8/2014 • • • • • • • Radiography Moisture/Density Gauge Radar Eddy current Thermography Acoustic emission etc. 20 methods in BS International Construction Week 17-19 Sep 2014, PWTC 17 Bar corrosion Bar size Bar location Lamination Honeycombing, voids Crack development Crack distribution Crack width Crack depth Thickness Elastic Modulus Strength Items NDT methods 1- Rebound hammer 2- Penetration resistance 3- Pull-out 4- Ultrasonic 5- Radar 6- Thermagraphy 7- Radiography 8- Acoustic emission 9- Magnetic or eddy current 10- Half-cell Potential 11- Photography 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 18 Bridges Foundation Dams Port Tunnel Building Structure Items Strength Elastic Modulus Deformation Crack Distribution Width Depth Defect Delamination Honeycombing, voids Backwall voids Rebar Location, size Corrosion Thickness very important 9/8/2014 important International Construction Week 17-19 Sep 2014, PWTC 19 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 20 Inspection Program Structures USA 9/8/2014 Building N/K Bridge every 2 yr Country Singapore Japan as every 5yr request N/K M’sia every 10y every yr every year (visual) (visual) International Construction Week 17-19 Sep 2014, PWTC 21 Code, standard availability Items 1.Test method 9 Civil constr . 9 2.Acceptance criteria 9 ?? 3.Personnel qualification 9 x 9/8/2014 Mechanical constr. International Construction Week 17-19 Sep 2014, PWTC 22 Prelimanary survey History, drawing Building Inspection Flow chart Visual inspection Evaluation No Record Yes (Grade III) SECOND SURVEY 9/8/2014 Estimate remaining life Carbonation Test THIRD SURVEY if Grade II, III & IV Rebar corrosion Repair if Grade III & IV THIRD SURVEY if crack is growing Crack survey Repair if Grade II & III and crack not growing THIRD SURVEY if Grade III & IV Water leaking Repair if Grade III & IV THIRD SURVEY if Grade II & III Concrete strength Repair if Grade II & III THIRD SURVEY if Grade III & IV Large Defelection Repair if Grade III & IV THIRD SURVEY if Grade II & III Surface Deterioration Repair if Grade II & III International Construction Week 17-19 Sep 2014, PWTC Record 23 Bridge Inspection Flow chart CONDITION OF BASE PLATE ROUTINE SURVEY REMARKABLE FOR REFERENCE 2 years interval RECORD RECORDS (DATA BANK) DETAILED SURVEY NO DECISION ON NECESSARY OF SURVEY NO YES INVESTIGATION NECESSARY OF REPAIR DECISION ON NECESSARY OF SURVEY CHECK ON DESIGN NO ADDITIONAL SURVEY VISUAL INSPECTION • The first survey • Observe any surface discontinuities • Visual features may be related to workmanship, structural serviceability & deterioration Typical defects in building 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 26 Typical defects in bridge Exposed bar Water leakage cracks Honeycomb spalling 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 27 Crack mapping/density 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 28 Acceptance criteria (building) 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 29 Acceptance criteria (building) BS8110‐2‐1985 • • • • • • • • 9/8/2014 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 8110‐1:1997 International Construction Week 17-19 Sep 2014, PWTC 30 Acceptance criteria (building) BS8110‐1‐1985 • 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 International Construction Week 17-19 Sep 2014, PWTC 31 Acceptance criteria (bridge) 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 32 BAR LOCATOR • • • • 9/8/2014 Electromagnetic covermeter or Radar technique Measure cover thickness Location of the reinforcement bar Accuracy: International Construction Week 17-19 Sep 2014, PWTC 33 Ground Penetrating Radar (GPR) • Uses electromagnetic waves to penetrate concrete • Propagation dependent on dielectric constant and electrical conductivity of media 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 35 NEUTRALIZATION/CARBONATION TEST/ pH TEST A purple‐red 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 ‐ red‐purple colouration. • Alternative method: by drilling into concrete member and drill powder may be sprayed by the indicator‐ observe change of colouration 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 37 REBOUND HAMMER • basically a surface hardness test • can be correlated with concrete strength • estimation error ~ 30% Correction for age effect 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 39 ULTRASONIC METHOD • • • • • • • • Pulse velocity Attenuation Phase change Monitor mixing materials, concrete uniformity Detect void or honeycombs Measure crack depth, slab thickness Depth of damage Estimate strength 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 International Construction Week 17-19 Sep 2014, PWTC 41 Testing methods • Resonance for determine Young Modulus • Through Transmission pulse method • Pulse echo method 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 42 Resonance Equipment 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 43 Pulse echo reflection 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 44 Ultrasonic tomography Panel hadapan – Imej tomografi Panel belakang - transduser Pemeriksaan terowong kereta api Imej tomografi yang dihasilkan http://www.acsys.ru/eng/production/detail/a1040-mira/ 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 45 Pulse Transmission • Direct technique • Diagonal (semi‐direct) • Surface (b) (a) (c) 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 46 Strength Estimation 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 47 Flaw Detection in Concrete • presence of internal defects in a sample of concrete gives rise to a decrease in amplitude of the received signal • Surface cracks are comparatively easy to evaluate using BS or phase reversal d 9/8/2014 = (a t − a t ) (t − t ) 2 2 2 1 2 2 2 2 1 2 2 1 International Construction Week 17-19 Sep 2014, PWTC 48 Acceptance criteria Pulse velocity (m/s) General Condition Above 4575 3660 – 4575 3050 – 3660 2135 – 3050 below 2135 Excellent Generally good Questionable Generally poor Very poor Penetration Test (Windsor probe) • based on depth of penetration of probe into concrete. • This can be directly correlated to compressive strength of concrete. 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 50 Radiography • X‐rays or gamma‐rays 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, honey‐combed and reinforcement bar condition and position. 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 51 Radiation sources • Iridium, Ir‐192 (206‐612 keV) – Half life= 74 days, Output = 0.48 – Penetration: 25mm~250mm concrete • Cobalt, Co‐60 (1173‐1333 keV) – Half life= 1925 days, Output =1.30 – Penetration: 125mm~500mm concrete • Linac/Betatron 8MeV X‐rays – penetrate 500mm~1600mm 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 52 Typical Exposure chart 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 53 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 International Construction Week 17-19 Sep 2014, PWTC 54 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 International Construction Week 17-19 Sep 2014, PWTC 55 Advantage and disadvantage of RT • High energy radiography has been found to be reliable NDT method for locating pre‐stressed 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 International Construction Week 17-19 Sep 2014, PWTC 56 Gamma/Neutron Gauge • Use to check degree of concrete compaction and moisture content 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 57 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 International Construction Week 17-19 Sep 2014, PWTC 58 Typical Thermographs compared to photographs Cold area Cold area 9/8/2014 International Construction Week 17-19 Sep 2014, PWTC 59 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 International Construction Week 17-19 Sep 2014, PWTC 60
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