Post on 18-Dec-2015
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CUBE TESTCUBE TEST
INDICATES ONLY POTENTIAL STRENGTHINDICATES ONLY POTENTIAL STRENGTH SUBJECT TO UNINTENTIONAL DEVIATIONS SUBJECT TO UNINTENTIONAL DEVIATIONS DELIBERATE DEVIATION ?DELIBERATE DEVIATION ? NOT A TRUE REPRESENTATIVE OF THE NOT A TRUE REPRESENTATIVE OF THE
STRUCTURE DUE TO PRESENCE OF STRUCTURE DUE TO PRESENCE OF STEEL, VOIDS, CRACKS & DIFFERENT STEEL, VOIDS, CRACKS & DIFFERENT DIMENSIONSDIMENSIONS
CANNOT BE VERIFIEDCANNOT BE VERIFIED CAN BE ONLY PERFORMED DURING CAN BE ONLY PERFORMED DURING
CONSTRUCTION STAGECONSTRUCTION STAGE
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N D T - OBJECTIVESN D T - OBJECTIVESTO ESTABLISH HOMOGENEITY OF TO ESTABLISH HOMOGENEITY OF
CONC.CONC.COMPARISON OF CONCRETE COMPARISON OF CONCRETE
QUALITY w.r.t. A STANDARDQUALITY w.r.t. A STANDARDDETECTION OF CRACKS, VOIDS/ DETECTION OF CRACKS, VOIDS/
OTHER IMPERFECTIONSOTHER IMPERFECTIONSMONITORING CHANGES IN MONITORING CHANGES IN
CONCRETE WITH PASSAGE OF TIMECONCRETE WITH PASSAGE OF TIMETO ESTABLISH QUALITY OF ONE TO ESTABLISH QUALITY OF ONE
ELEMENT w.r.t. ANOTHERELEMENT w.r.t. ANOTHER
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N D T - OBJECTIVESN D T - OBJECTIVES
ASSESSMENT OF EXISTING STRUCTURE ASSESSMENT OF EXISTING STRUCTURE FOR REHABILITATION PLANNINGFOR REHABILITATION PLANNING
AS AN ALTERNATIVE TESTING METHOD AS AN ALTERNATIVE TESTING METHOD IF CUBE RESULTS RAISE DOUBTS IF CUBE RESULTS RAISE DOUBTS ABOUT CONCRETE QUALITY (POST ABOUT CONCRETE QUALITY (POST MORTEM)MORTEM)
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N D T - METHODSN D T - METHODS
VISUAL INSPECTIONVISUAL INSPECTION REBOUND HAMMERREBOUND HAMMER ULTRASONIC PULSE VELOCITY METERULTRASONIC PULSE VELOCITY METER PENETRATION RESISTANCEPENETRATION RESISTANCE PULL OUT STRENGTHPULL OUT STRENGTH COVER METERCOVER METER CARBONATION DEPTHCARBONATION DEPTH CORROSION MAPPINGCORROSION MAPPING MATURITY METERMATURITY METER PERMEABILITY TESTPERMEABILITY TEST RADIOGRAPHYRADIOGRAPHY
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REBOUND HAMMERREBOUND HAMMER
MOST COMMON NDT METHODMOST COMMON NDT METHOD DEVELOPED IN 1948DEVELOPED IN 1948 MEASURES REBOUND HARDNESS OF MEASURES REBOUND HARDNESS OF
CONCRETECONCRETE NO THEORETICAL RELATIONSHIP NO THEORETICAL RELATIONSHIP
AVAILABLE FOR ASSESSMENT OF AVAILABLE FOR ASSESSMENT OF STRENGTHSTRENGTH
EMPIRICAL RELATIONSHIP BETWEEN EMPIRICAL RELATIONSHIP BETWEEN REBOUND HARDNESS AND STRENGTH REBOUND HARDNESS AND STRENGTH DEVELOPEDDEVELOPED
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REBOUND HAMMER - GUIDELINESREBOUND HAMMER - GUIDELINES
CONDUCT ON SMOOTH AND UNIFORM CONDUCT ON SMOOTH AND UNIFORM FACEFACE
AVOID ROUGH SPOTS, HONEY COMBSAVOID ROUGH SPOTS, HONEY COMBS AVOID TROWELLED SURFACESAVOID TROWELLED SURFACES THIN SECTIONS (< 100 mm) SHOULD BE THIN SECTIONS (< 100 mm) SHOULD BE
BACKED UP TO AVOID DEFLECTIONSBACKED UP TO AVOID DEFLECTIONS TAKE ATLEAST 15 REBOUND READINGS TAKE ATLEAST 15 REBOUND READINGS
IN ANY ONE TESTIN ANY ONE TEST
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REBOUND HAMMER - GUIDELINESREBOUND HAMMER - GUIDELINES
CALCULATE THE MEANCALCULATE THE MEAN COMPARE DEVIATION OF READINGS COMPARE DEVIATION OF READINGS
FROM THE MEANFROM THE MEAN TEST IS CONSIDERED RELIABLE IF THE TEST IS CONSIDERED RELIABLE IF THE
DEVIATION OF TEN READINGS IS NOT DEVIATION OF TEN READINGS IS NOT MORE THAN THE FOLLOWING:MORE THAN THE FOLLOWING:
REBOUND VALUEREBOUND VALUE 1515 3030 4545
DEVIATIONDEVIATION 2.52.5 33 3.53.5
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REBOUND HAMMER - GUIDELINESREBOUND HAMMER - GUIDELINES
USE BEST 10 READINGS FOR USE BEST 10 READINGS FOR CALCULATING THE MEANCALCULATING THE MEAN
DETERMINE COMPRESSIVE STRENGTH DETERMINE COMPRESSIVE STRENGTH BY REFERRING TO REBOUND NUMBER BY REFERRING TO REBOUND NUMBER Vs STRENGTH CHARTS AGAINST THE Vs STRENGTH CHARTS AGAINST THE MEAN VALUEMEAN VALUE
BEST ACCURACY ACHIEVEABLE IS BEST ACCURACY ACHIEVEABLE IS WITHIN WITHIN ++ 20% 20%
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FACTORS AFFECTING REBOUND FACTORS AFFECTING REBOUND VALUEVALUE
TYPE OF AGGREGATESTYPE OF AGGREGATES DEGREE OF COMPACTIONDEGREE OF COMPACTION AGE OF CONCRETEAGE OF CONCRETE DRYNESS/WETNESS OF THE SURFACEDRYNESS/WETNESS OF THE SURFACE RIGIDITY OF THE MEMBERRIGIDITY OF THE MEMBER SURFACE FINISH OF CONCRETE- MOULDED/ SURFACE FINISH OF CONCRETE- MOULDED/
TROWELEDTROWELED MAINTENANCE OF REBOUND HAMMERMAINTENANCE OF REBOUND HAMMER INCLINATION OF THE REBOUND HAMMERINCLINATION OF THE REBOUND HAMMER TYPE OF CEMENTTYPE OF CEMENT CARBONATIONCARBONATION COVERCOVER
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PULSE VELOCITY METHODPULSE VELOCITY METHOD
DEVELOPED IN 1940s DEVELOPED IN 1940s BASED UPON PROPOGATION OF BASED UPON PROPOGATION OF
ULTRASONIC WAVES IN ELASTIC ULTRASONIC WAVES IN ELASTIC MEDIUMMEDIUM
MEASURES VELOCITY OF PROPOGATION MEASURES VELOCITY OF PROPOGATION OF ULTRASONIC WAVESOF ULTRASONIC WAVES
VELOCITY RELATED TO THE DENSITY OF VELOCITY RELATED TO THE DENSITY OF THE MEDIUM V=(E/p)THE MEDIUM V=(E/p)1/21/2
STRENGTH IS DEDUCED FROM THE STRENGTH IS DEDUCED FROM THE DENSITY OF THE MEDIUMDENSITY OF THE MEDIUM
FREQUENCY OF WAVES USED - 20 - 150 FREQUENCY OF WAVES USED - 20 - 150 kHzkHz
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PULSE VELOCITY METHODPULSE VELOCITY METHOD
TYPES OF TESTING METHODTYPES OF TESTING METHODDIRECT TRANSMISSION DIRECT TRANSMISSION SEMI DIRECT TRANSMISSIONSEMI DIRECT TRANSMISSIONSURFACE TRANSMISSIONSURFACE TRANSMISSION
DIRECT TRANSMISSION METHOD IS THE DIRECT TRANSMISSION METHOD IS THE BEST BUT IT REQUIRES ACCESS TO TWO BEST BUT IT REQUIRES ACCESS TO TWO OPPOSITE SIDES OF CONCRETE OPPOSITE SIDES OF CONCRETE MEMBER MEMBER
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PULSE VELOCITY RATINGSPULSE VELOCITY RATINGS
QUALITY PULSE VELOCITY km/sec
Excellent > 4.6
Good 3.7 to 4.6
Fair 3.0 to 3.7
Poor 2.1 to 3.0
Very poor < 2.1
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FACTORS AFFECTING PULSE FACTORS AFFECTING PULSE VELOCITYVELOCITY
DEGREE OF COUPLINGDEGREE OF COUPLING PRESENCE OF REINFORCEMENTPRESENCE OF REINFORCEMENT CONCRETE TEMPERATURECONCRETE TEMPERATURE MOISTURE CONTENTMOISTURE CONTENT MIX PROPORTIONMIX PROPORTION AGE OF CONCRETEAGE OF CONCRETE STRESS LEVEL IN CONCRETESTRESS LEVEL IN CONCRETE CONCRETE STRENGTH CAN BE CONCRETE STRENGTH CAN BE
PREDICTED WITHIN PREDICTED WITHIN ++ 20% PROVIDED 20% PROVIDED CALIBRATION CURVE IS ESTABLISHEDCALIBRATION CURVE IS ESTABLISHED
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APPLICATIONS OF PULSE APPLICATIONS OF PULSE VELOCITY METHODVELOCITY METHOD
MAIN APPLICATION FOR ASSESSMENT MAIN APPLICATION FOR ASSESSMENT OF CONCRETE UNIFORMITYOF CONCRETE UNIFORMITY
TO ESTABLISH AREAS OF TO ESTABLISH AREAS OF DETERIORATED CONCRETEDETERIORATED CONCRETE
DETECTION OF CRACKS DETECTION OF CRACKS CALCULATION OF DYNAMIC YOUNG’S CALCULATION OF DYNAMIC YOUNG’S
MODULUSMODULUS
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COVER METERCOVER METER
COVER IS A VERY IMPORTANT COVER IS A VERY IMPORTANT PARAMETER DICTATING DURABILITY OF PARAMETER DICTATING DURABILITY OF CONCRETECONCRETE
COVER PROVIDED IS INADEQUATE COVER PROVIDED IS INADEQUATE MORE OFTEN THAN NOTMORE OFTEN THAN NOT
CONVENTIONALLY PROVISION OF CONVENTIONALLY PROVISION OF COVER IS CHECKED PRIOR TO COVER IS CHECKED PRIOR TO CONCRETING CONCRETING
POST FACTO ASSESSMENT OF COVER IS POST FACTO ASSESSMENT OF COVER IS POSSIBLE THROUGH COVER METERSPOSSIBLE THROUGH COVER METERS
2020
COVER METERCOVER METER
BASED ON MAGNETIC PRINCIPLEBASED ON MAGNETIC PRINCIPLE RANGE OF MEASUREMENT POSSIBLE IS RANGE OF MEASUREMENT POSSIBLE IS
0-75 mm0-75 mm ACCURACY WITHIN 6 mmACCURACY WITHIN 6 mm NOT VERY EFFECTIVE IN HEAVILY NOT VERY EFFECTIVE IN HEAVILY
REINFORCED MEMBERS OR MEMBERS REINFORCED MEMBERS OR MEMBERS WITH SPIRAL REINFORCEMENTWITH SPIRAL REINFORCEMENT
SIZE OF THE REINFORCEMENT BAR IS SIZE OF THE REINFORCEMENT BAR IS REQUIRED TO BE KNOWN FOR REQUIRED TO BE KNOWN FOR ACCURATE ASSESSMENT OF COVERACCURATE ASSESSMENT OF COVER
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APPLICATION OF COVER METERAPPLICATION OF COVER METER
REHABILITATION PLANNINGREHABILITATION PLANNING ASSESSMENT OF RESIDUAL TIME TILL ASSESSMENT OF RESIDUAL TIME TILL
INITIATION OF CORROSIONINITIATION OF CORROSION TO IMPROVE QUALITY CONTROL DURING TO IMPROVE QUALITY CONTROL DURING
CONSTRUCTIONCONSTRUCTION IDENTIFICATION OF LOCATION OF IDENTIFICATION OF LOCATION OF
REINFORCEMENT BAR WITH THE REINFORCEMENT BAR WITH THE FOLLOWING APPLICATIONSFOLLOWING APPLICATIONSHELPS IN AVOIDING DRILLING INTO THE HELPS IN AVOIDING DRILLING INTO THE
REINFORCEMENTREINFORCEMENTTO AVOID REINFORCEMENT IN PULSE TO AVOID REINFORCEMENT IN PULSE
VELOCITY MEASUREMENTSVELOCITY MEASUREMENTS
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CARBONATION DEPTHCARBONATION DEPTH
CARBONATION IS CHEMICAL REACTION CARBONATION IS CHEMICAL REACTION BETWEEN Ca (OH)BETWEEN Ca (OH)22 AND CO AND CO22 OF THE OF THE
ATMOSPHEREATMOSPHERE CARBONATION DESTROYS PASSIVE CARBONATION DESTROYS PASSIVE
PROTECTION PROVIDED BY CONCRETE PROTECTION PROVIDED BY CONCRETE TO THE REINFORCEMENTTO THE REINFORCEMENT
CARBONATION PROCEEDS FROM THE CARBONATION PROCEEDS FROM THE SURFACE INTO THE CONCRETESURFACE INTO THE CONCRETE
WHEN DEPTH OF CARBONATION WHEN DEPTH OF CARBONATION EQUALS CONCRETE COVER EQUALS CONCRETE COVER REINFORCEMENT CORROSION IS REINFORCEMENT CORROSION IS IMMINENTIMMINENT
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CARBONATION DEPTHCARBONATION DEPTH
METHOD OF ASSESSMENTMETHOD OF ASSESSMENTDRILL INTO CONCRETEDRILL INTO CONCRETESPRAY PHENOLPHTHALEIN SOLUTION SPRAY PHENOLPHTHALEIN SOLUTION UNCARBONATED CONCRETE WILL SHOW UNCARBONATED CONCRETE WILL SHOW
BRIGTH PINK STAINBRIGTH PINK STAINCARBONATED CONCRETE WILL NOT CARBONATED CONCRETE WILL NOT
CHANGE COLOURCHANGE COLOURWITH THE ABOVE VISUAL INDICATION DEPTH WITH THE ABOVE VISUAL INDICATION DEPTH
OF CARBONATION CAN BE EASILY OF CARBONATION CAN BE EASILY MEASUREDMEASURED
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LIMITATIONS OF N D TLIMITATIONS OF N D T
ALL NDT METHODS ARE INDIRECTALL NDT METHODS ARE INDIRECT CORELATION BETWEEN MEASURED CORELATION BETWEEN MEASURED
PARAMETER AND CONCRETE STRENGTH PARAMETER AND CONCRETE STRENGTH IS NEVER EXACT.IS NEVER EXACT.
EFFECTIVENESS OF NDT REDUCES WITH EFFECTIVENESS OF NDT REDUCES WITH HETEROGENEITY OF THE MATERIAL HETEROGENEITY OF THE MATERIAL
RESULTS ARE DEPENDENT ON TOO RESULTS ARE DEPENDENT ON TOO MANY PARAMETERSMANY PARAMETERS
NORMALLY ACHIEVEABLE LEVEL OF NORMALLY ACHIEVEABLE LEVEL OF ACCURACY IS ACCURACY IS + + 25%25%
INTERPRETATION OF RESULTS REQUIRE INTERPRETATION OF RESULTS REQUIRE INTUITIVE JUDGEMENT INTUITIVE JUDGEMENT