Diagnosis, Inspection, Testing And Repair Of Reinforced Concrete Structures

Diagnosis, Inspection, Testing And Repair Of Reinforced Concrete Structures

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Diagnosis, Inspection, Testing And Repair Of Reinforced Concrete Structures Page 1 of 75 MG Associates 28/08/00 1. INTRODUCTION . .......................................................................................................................... 3 2. WHAT IS CONCRETE? . ............................................................................................................... 4 2.1 CEMENT . ........................................................................................................................................ 4 2.1.1 Ordinary Portland Cement. .................................................................................................. 4 2.1.2 Sulfate Resisting Cement . ..................................................................................................... 4 2.1.3 High Alumina Cement . ......................................................................................................... 4 2.2 WATER. .......................................................................................................................................... 4 2.3 AGGREGATE. .................................................................................................................................. 4 2.4 STEEL. ............................................................................................................................................ 5 2.5 ADMIXTURES . ................................................................................................................................ 5 3. RECOGNISING CONCRETE DEFECTS . .................................................................................. 6 3.1 STRUCTURAL FAILURE. .................................................................................................................. 6 3.2 CORROSION OF STEEL . ................................................................................................................... 6 3.3 ALKALI SILICA REACTION. ............................................................................................................. 7 3.4 FROST DAMAGE . ............................................................................................................................ 7 SHRINKABLE AGGREGATES. .................................................................................................................... 7 3.6 CHEMICAL ATTACK . ...................................................................................................................... 8 3.6.1 Sulfate Attack. ....................................................................................................................... 8 3.6.2 Acid Attack. ........................................................................................................................... 9 3.6.3 Other Contaminants . ............................................................................................................ 9 FIRE DAMAGE. ........................................................................................................................................ 9 3.8 POOR QUALITY CONSTRUCTION. .................................................................................................. 11 3.9 PLASTIC CRACKING. ..................................................................................................................... 11 Plastic Settlement Cracks . ............................................................................................................... 11 3.9.2 Plastic Shrinkage Cracks. ................................................................................................... 11 3.10 THERMAL CRACKING AND DELAYED ETTRINGITE FORMATION. .............................................. 12 4. INVESTIGATION OF REINFORCED CONCRETE DETERIORATION. ........................... 15 4.1 THE TWO STAGE APPROACH. ....................................................................................................... 15 4.2 VISUAL SURVEY. .......................................................................................................................... 15 4.3 COVERMETER SURVEY. ................................................................................................................ 15 4.4 ULTRASONIC PULSE VELOCITY MEASUREMENT (PUNDIT). .......................................................... 16 4.4.1 Theory of UPV Measurement . ............................................................................................ 16 4.4.2 Testing Concrete. ................................................................................................................ 23 4.5 CHEMICAL TESTS. ........................................................................................................................ 31 4.5.1 Chloride Content . ............................................................................................................... 31 4.5.2 Cement Content . ................................................................................................................. 32 4.5.3 Depth of Carbonation. ........................................................................................................ 33 4.5.4 Sulfate Content . .................................................................................................................. 34 4.5.5 High Alumina Cement . ....................................................................................................... 35 4.6 COMPRESSIVE STRENGTH DETERMINATION. ................................................................................ 36 4.7 PETROGRAPHIC EXAMINATION. .................................................................................................... 37 4.7.1 Preliminary examination. ................................................................................................... 37 4.7.2 Polished surfaces. ............................................................................................................... 37 4.7.3 Thin sections. ...................................................................................................................... 38 4.7.4 Broken surfaces . ................................................................................................................. 38 4.7.5 Composition. ....................................................................................................................... 38 4.7.6 Water/cement ratio . ............................................................................................................ 39 4.8 SURFACE HARDNESS METHODS . .................................................................................................. 39 4.8.1 Rebound Hammer - Schmidt Hammer. ............................................................................... 39 4.8.2 Rebound test equipment and operation . ............................................................................. 39 4.8.3 Procedure . .......................................................................................................................... 40 4.8.4 Theory, calibration and interpretation. .............................................................................. 40 4.8.5 Factors influencing test results. .......................................................................................... 40 4.8.6 Calibration . ........................................................................................................................ 43
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Diagnosis, Inspection, Testing And Repair Of Reinforced Concrete Structures Page 2 of 75 MG Associates 28/08/00 4.8.7 Other Near to Surface Strength Tests. ................................................................................ 43 4.9 RADAR PROFILING . ...................................................................................................................... 43 4.9.1 Radar systems. .................................................................................................................... 43 4.9.2 Radar Equipment. ............................................................................................................... 44 4.9.3 Structural applications and limitations . ............................................................................. 44 4.10 ACOUSTIC EMISSION . ............................................................................................................... 45 4.10.1 Theory . ........................................................................................................................... 45 4.10.2 Equipment . ..................................................................................................................... 46 4.10.3 Applications and Limitations . ........................................................................................ 46 4.10.4 References . ..................................................................................................................... 47 4.11 INFRA RED THERMOGRAPHY . .................................................................................................. 47 5. TESTING FOR REINFORCEMENT CORROSION. ............................................................... 49 5.1 HALF CELL POTENTIAL TESTING . ................................................................................................ 49 5.1.1 Factors affecting the potential field. ................................................................................... 50 5.1.2 Polarisation Effects . ........................................................................................................... 50 5.1.3 Procedure for Measurement. .............................................................................................. 50 5.1.4 Results and Interpretation . ................................................................................................. 51 5.2 RESISTIVITY. ................................................................................................................................ 53 5.2.1 Equipment & Use. ............................................................................................................... 53 5.2.2 Interpretation. ..................................................................................................................... 53 5.2.3 Limitations. ......................................................................................................................... 54 5.3 CORROSION RATE . ....................................................................................................................... 54 5.3.1 Property to be Measured. ................................................................................................... 54 5.3.2 Equipment & Use - Linear Polarisation. ............................................................................ 55 5.3.3 Interpretation - Linear Polarisation. .................................................................................. 56 6. CONCRETE REPAIRS. ............................................................................................................... 59 6.1 PATCH REPAIRS. ........................................................................................................................... 59 6.1.1 Patch Repairing Carbonation Induced Corrosion . ............................................................ 59 6.1.2 Patch Repairing Chloride Induced Corrosion. .................................................................. 60 6.1.3 The incipient anode effect. .................................................................................................. 61 6.2 CATHODIC PROTECTION. .............................................................................................................. 62 6.2.1 Basic Electrochemistry. ...................................................................................................... 62 6.2.2 Corrosion. ........................................................................................................................... 62 6.2.3 Reactivity . ........................................................................................................................... 62 6.2.4 Cathodic Protection. ........................................................................................................... 63 6.2.5 Practical Anode Systems . ................................................................................................... 63 6.3 ELECTROCHEMICAL CHLORIDE EXTRACTION (DESALINATION) AND REALKALISATION. .............. 64 6.3.1 Introduction. ....................................................................................................................... 64 6.3.2 The Mechanisms of Corrosion of Steel in Concrete . .......................................................... 64 6.3.3 Electrochemical Processes. ................................................................................................ 65 6.3.4 Chloride Removal. .............................................................................................................. 66 6.3.5 Realkalisation. .................................................................................................................... 71 6.3.6 Conclusions . ....................................................................................................................... 73 6.3.7 Acknowledgements. ............................................................................................................. 73 6.3.8 Recommended Reading on Chloride Removal and Realkalisation . ................................... 74 6.4 CORROSION INHIBITORS. .............................................................................................................. 75
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This note was uploaded on 11/30/2010 for the course CIIVIL WNG 33155 taught by Professor Y.bahie during the Spring '10 term at The British University in Egypt.

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Diagnosis, Inspection, Testing And Repair Of Reinforced Concrete Structures

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