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Case study on non destructive testing on concrete structures

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  • 1. CASE STUDY ON NON-DESTRUCTIVE TESTING ON CONCRETE STRUCTURES Submitted By : Ankita Kulkarni (243037) Sandhya Silotia (243072) Sangamesh Kotarki (243074) Non-Destructive Testing on Concrete Structures - A Case Study Guided by : Prof. R. Satish Kumar
  • 2. Index:
    • Objective
    • Scope
    • Why NDT?
    • Applications of NDT
    • Various Methods of NDT
    • Case Studies
    • Conclusions
    • Remedial Measures
    • Limitations
    • Bibliography
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 3. Objective
    • To Study the use, methodology & applicability of non destructive testing methods to check integrity of concrete structures through a case study.
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 4. Scope:
    • Suggest the methodology to be followed & applicability of non destructive testing.
    • Automatic interpretation of data from NDT, with the goal of detecting flaws accurately and efficiently.
    • To propose retrofitting techniques for structures failing in this kind of testing.
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 5. Case Studies :
    • 1. EIGHT LANE ACCESS CONTROLLED EXPRESSWAY AS OUTER RING ROAD TO HYDERABAD CITY, PHASE II KOLLUR (KM. 12+000 TO PATANCHERU (KM. 23+700)
    • 2. DRDL Laboratory building, single storied at Chandrayangutta, Secunderabad
    • 3. Ambuja cements ltd.,Rajasthan
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 6. Non destructive testing
    • Non destructive testing is a technique for checking structural integrity after concrete hardening without damaging it.
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 7. Various methods of NDT
    • UPSV Test (Ultra sonic pulse velocity test)
    • Schmidt rebound hammer test
      • Carbonation depth measurement test
      • Half-cell potentiometer test
      • Cover meter test
    • Penetration Resistance test
    • Resistivity measurement
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 8. Why NDT?
    • Strength on concrete depends on material, proper mixing & also workmanship at the time of placing
    • Conventional methods of testing of concrete does provide solution to assess actual strength or internal structure after hardening of concrete
    • In some cases, it required to assess of concrete damaged due to fire or any other natural calamity due judge the condition of structure
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 9. Application of NDT
    • quality control of pre-cast units or construction in situ
    • confirming or negating doubt concerning the workmanship involved in batching, mixing, placing, compacting or curing of concrete
    • location and determination of the extent of cracks, voids, honeycombing and similar defects within a concrete structure
    • determining the position, quantity or condition of reinforcement
    • confirming or locating suspected deterioration of concrete resulting from such factors as
    • overloading, fatigue, external or internal chemical attack or change, fire, explosion, environmental effect
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 10. USPV Test
    • This test is used for determination of the uniformity of concrete in and between members.
    • Reference code: IS 13311Part I 199
    • Principle: the velocity of an ultrasonic pulse through any material depends upon the density, modulus of elasticity and Poisson’s ratio of the material.
    • Higher is the velocity, better is the quality of concrete
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 11. UPSV Contd…Equipment:
      • (a) Electrical pulse generator
      • (b) Pair of transducers
      • (c) Amplifier
      • (d) Electronic timing machine
    UPSV Equipment
    • Equipment should be capable of measuring transit time over path lengths ranging from about 100 mm to the maximum thickness to be inspected to an accuracy of ±1%
    • Cost of equipment: Rs.2.15 lakhs
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 12. UPSV Contd…. Methodology
    • Calibration: done by measuring transit time on standard calibration rod.
    • Transducers arrangement: 3 methods
    • Direct Transmission
    c) Surface Transmission b) Semi Direct Transmission Non-Destructive Testing on Concrete Structures - A Case Study
  • 13. Contd… USPV
        • Velocity criterion for concrete quality grading is given by IS 13311 (Part-I):1992
    Non-Destructive Testing on Concrete Structures - A Case Study Sr. No. Ultrasonic Pulse Velocity by Cross probing (Km/Sec) Concrete quality grading 1 Above 4.5 Excellent 2 3.5 to 4.5 Good 3 3.5 to 4.5 Medium 4 3.5 to 4.5 Doubtful
  • 14. SCHMIDT REBOUND HAMMER TEST
    • The Schmidt rebound hammer is basically a surface hardness tester.
    • IS: 13311 (Part 2): 1992 & BS 1881: Part 202: 1986
    • Principle :the rebound of an elastic mass depends on the hardness of the surface against which mass strikes.
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 15. Contd… Rebound Hammer
    • Equipment: It Consist of a spring control hammer that slides on a plunger within a tubular housing. When the plunger is pressed against the surface of the concrete, the mass rebound from the plunger. It reacts against the force of spring. The Distance travelled by the mass, is called rebound number.
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 16. Contd… Rebound Hammer Non-Destructive Testing on Concrete Structures - A Case Study
  • 17. CARBONATION DEPTH MEASUREMENT TEST
    • Carbonation of concrete occurs when the carbon dioxide, in the atmosphere in the presence of moisture, reacts with hydrated cement minerals to produce carbonates
    • Due alkaline nature of concrete, reinforcement is protected from corrosion. This is neutralized by carbonation, thus reinforcement becomes prone to in presence moisture and oxygen.
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 18. Contd… Carbonation Test
    • The extent of carbonation is determined by testing concrete surface with a 1% phenolphthalein solution
    • The 1% phenolthalein solution is made by dissolving 1gm of phenolthalein in 90 cc of ethanol & the making it to 100cc by adding distilled water.
    • Change in colour is observed after test:
    • No change in colour layer: Carbonation affected
    • Purple: No cabonation has taken place
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 19. HALF-CELL ELECTRICAL POTENTIAL METHOD
    • This test is used to assess the corrosion conditions in a reinforced concrete structure.
    • ASTM C876 - 91
    • The apparatus includes copper-copper sulphate half-cell, connecting wires and a high impedance voltmeter
    • external cathode is provided in the form of copper rod and copper sulphate solution in the cell. Any point on reinforcement bar inside the concrete body functioning as anode when connected electrically to cathodic half-cell generates e.m.f. This is measured by connecting a milli voltmeter in the circuit
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 20. Contd… Half Cell Electrical Method The possibility of active corrosion is found out according to guideline below Non-Destructive Testing on Concrete Structures - A Case Study Half cell potential (mV) reading Percentage chance of active corrosion < -350 90% -200 to –350 50% > -200 10%
  • 21. Cover meter test
    • This test is used to assess the location and diameter of reinforcement bars and concrete cover.
    • Principle: based measurement of change of an elctromagnetic field caused by steel embedded in the concrete.
    • Equipment: profometer comprise a search head, meter and interconnecting cable. The concrete surface is scanned, with the search head kept in contact with it while the meter indicates, by analogue or digital means, the proximity of reinforcement
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 22. Case Study 1: EXPRESSWAY, KOLLUR
    • Structure: EIGHT LANE ACCESS CONTROLLED EXPRESSWAY AS OUTER RING ROAD TO HYDERABAD CITY, PHASE II KOLLUR (KM. 12+000 TO PATANCHERU (KM. 23+700)
    • Test conducted:
    • Rebound Hammer tests to assess the in situ compressive strength of cover concrete.
    • USPV tests to assess the integrity of concrete
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 23. Case study 1:
    • Test results:
      • USPV TEST RESULTS
      • Rebound Hammer test results
    • Results & Inferences:
      • Concrete quality is found from “good to excellent” according to UPSV tests results
      • Concrete strength is varies from M35- M45 in rebound hammer test
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 24. Case Study 2 : DRDL Hyderabad
    • Structure: DRDL laboratory building, single storied
      • Columns size( B1 & B4) : 1’6” x 1’6”
      • Columns size( A1, A2, A3, A4, B2, B3, C1, C2, C3 & C4 ) : 1’0” x 1’6”
      • Beam size –2’4” x 1’0”
    • Test conducted:
    • UPSV
    • Rebound hammer test
    • Test results:
    • UPSV test:
    • Rebound hammer
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 25. Case study 2:
    • Analysis & Results:
      • Concrete quality is found to be “good” at maximum locations .At some places it is found “medium & doubtful”.
      • On analyzing above rebound hammer test, it is found that the strength produced by the structures are more than the strength of Concrete of M-25.
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 26. Case study 2: Non-Destructive Testing on Concrete Structures - A Case Study
  • 27. Case Study 3: Ambuja cements ltd.,Rajasthan
    • Structures:
      • Cement silo: Dia 16.7 M & Height 51.0 M
    • Test conducted:
    • Rebound Hammer tests to assess the in situ compressive strength of cover concrete.
    • USPV tests to assess the integrity of concrete.
    • Carbonation test to assess the depth of carbonated concrete.
    • Half cell potentiometer test to assess the probability of active corrosion.
    • Cover Meter test to estimate the cover provided.
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 28. Case Study 3:
    • Tests results:
      • UPSV & Rebound hammer:
      • Half cell potentiometer :
      • Cover meter:
      • Carbonation depth:
    • Results analysis & Inferences:
      • columns ground level wall and Upper level wall “Medium to good quality concrete”
      • 10% probability of active corrosion exists.
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 29. Case study 3:
    • Results & Inferences:
      • average cover provided to reinforcement in columns and wall is about 40 mm which adequate acc. To IS 456
      • The carbonation test results on cores s as well as drill powder from concrete suggest that average depth of carbonation for columns is upto 10 mm & Wall can be considered upto 20mm, which can be considered as normal considering the age of the structure.
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 30. Case study 3: Non-Destructive Testing on Concrete Structures - A Case Study Silo structure Fine crack in silo top slab
  • 31. Conclusion :
    • Various NDT methods can be used depending upon the type & age of structure to check the integrity of structure.
    • USPV, rebound hammer & covermeter can be applied to newly constructed structures to check the quality of concrete adequacy of cover before applying live load to the structures.
    • Half cell potentiometer & carbonation test can be applied to old structure to acess to carbonation depth & amount of corrosion occurred.
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 32. Remedial measures:
    • Replacement of cover concrete by microconcrete
    • Polymer Modified Mortar Treatment
    • Protective Coating
    • Jacketing
    • Water proofing to slab
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 33. Limitation:
    • Lack of access, especially inside silo structures is a serious limitation in assessing the integrity of silo walls
    • Slabs are covered with water proofing membrane, it becomes difficult to get accurate through NDT.
    • If spalling or cracks are observed ,concrete remains no longer homogeneous, and tests like UPSV & rebound hammer becomes inapplicable, equipments for NDT are not made in India.
    • Equipments are very costly and not easily available.
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 34. Biblography:
    • Guidebook on non-destructive testing of concrete structures - INTERNATIONAL ATOMIC ENERGY AGENCY, VIENNA, 2002.
    • IS 13311 : Part 1 : 1992 Non-destructive testing of concrete: Part 1 Ultrasonic pluse velocity
    • IS 13311 : Part 2 : 1992 Methods of non-destructive testing of concrete: Part 2 Rebound hammer
    • MS shetty:Concrete technology
    Non-Destructive Testing on Concrete Structures - A Case Study
  • 35. Thank you for Your Attention… Non-Destructive Testing on Concrete Structures - A Case Study

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