UNIT- 1 Page. No. 1.1 Introduction 1 1.2 Introduction to rehabilitation and repairs 1 1.3 Site selection and site development errors 1 1.4 Design errors ……………………………………………………………..…...1

1.5 Construction errors 1 1.6 Material deficiencies 2 1.7 Operational errors 2

1.8 Principles of rehabilitation ……………………………………………..…..2

1.8.1 Elimination 2 1.8.2 Separation 2 1.8.3 Ventilation 2

1.9 General areas of repair/rehabilitation work ………………………..….2 1.10 Major types of repair 2 1.11 Brick walls 3

1.11.1 Problems with brick (structural problems) 3 1.11.2 A couple of don'ts for brick …………………………..…….3 1.11.3 Repair work 3 1.11.4 Removal of organic growth 4

1.12 Plaster walls 4

1.12.1 Should you repair or replace? ……………….…………..…..4 1.12.2 Plaster damage 4

1.13 RCC repairs 5

1.13.1 Problems in RCC structures 5

1.13.2 Form and pump technique ……………………………..….5 1.13.3 Surface repair of vertical location (column) 5 1.13.4 Surface repair of overhead location (beam) 6 1.13.5 Advantages of form and pump technique 6

1.14 Conclusion 6 1.15 Condition assessment of buildings for repair 7 1.16 Objective of Assessment 7 1.17 Factors causing building distress 7 1.18 Rehabilitation and seismic retrofitting of buildings …………………………….7 1.19 Condition assessment of buildings 8

1.19.1 Main objective of condition assessment 8

1.19.2 Main steps of condition assessment 8

1.19.3 Typical visible detrimental to the safety of buildings 8

1.19.4 Main causes of such distress in buildings 9 1.20 Methodology of condition assessment …………………………………………....9

1.20.1 Rapid (visual) investigation 9

1.20.2 Information needed for rapid investigation 9

1.20.3 Details in visual investigation 10

1.20.4 Observation of settlement or differential settlement of buildings 1.21 Detailed investigations ……………………………………………………………….11

1.21.1 Need and actions 11

1.21.2 Tests for assessment of in-situ quality of reinforced concrete11

1.21.3 Test of concrete strength 12

1.21.4 Rebound hammer test 13

1.21.5 Ultrasonic pulse velocity (UPV) technique 14

1.21.6 Core tests 15 1.22 Partially destructive tests …………………………………………….……….……15

1.22.1 Penetration resistance 16

1.22.2 Pull-out testing 17

1.22.3 Pull-off method 17

1.22.4 Interpretation about corrosion based on chemical analysis 18

1.22.5 Location od steel reinforcement in RC structures by NDT 19

1.22.6 Samples of steel reinforcement for determining the strength 19

1.22.7 Corrosion of reinforcement in RC structures. 19 1.23 Soil profiles at the site …………………………………………………………..….19 1.24 Concluding remarks 20

UNIT – 2

2.1 Durability 21

2.2 Material related failures 21

2.3 Environmental related causes of concrete durability problems 21

2.4 Thermal shrinkage 22

2.5 Factors affecting thermal stresses ………………………………….……23 2.5.1 Degree of restraint (kr ) 23

2.5.2 Temperature change 24

2.6 Thermal properties of concrete 24

2.7 Extensibility and cracking ……………………………………………..…..26 2.7.1 Modulus of elasticity 26

2.7.2 Creep 26

2.7.3 Tensile strength 26

2.8 Environmental-related causes of concrete durability problems …….26 2.9 Temperature 27

2.10 Environmental-related problems of temperature 28

2.10.1 Daily changes in temperature 28

2.10.2 Seasonal changes in temperature 28

2.11 Moisture 29

2.12 Environmental-related problem of moisture ………………………..…..29 2.12.1 Carbonation 29

2.12.2 Moisture cycles 30

2.12.3 Contaminants 31

2.13 Physical factors 31

2.14 Environmental-related physical problems ………………………..….32

2.15 Cavitation 32

2.16 Fire 32

2.17 Biological factors 34

2.18 Masses on concrete. 34 2.19 Seaweed on concrete 34

2.20 Environmental-related biological problems …………………………35

2.21 Classification of exposure conditions 35

2.22 Lack of durability 36

2.23 Factors affecting the duraility of concrete …………………………36

2.24 Permeability of concrete 37

2.25 Chemical factors 38

2.25.1 Chemical corrosion 38

2.25.2 Chemical attack 40

2.26 Alkali aggregate reaction in concrete (AAR) …………………….….41

2.27 Sources of alkalis in concrete 42 2.27.1 Cement 42 2.27.2 Pozzolans 42 2.27.3 Aggregate 43 2.27.4 Admixtures 43 2.27.5 Water 43 2.27.6 Alkalis from outside the concrete ……………………..…43

2.28 Alkali content and AAR 43 2.29 General types of AAR 44 2.30 Tests for aggregate reactivity 44 2.31 Deterioration of concrete due to aggressive agencies ………….……..45 2.32 Chemical process 46 2.33 Main factors affecting sulphate attack 47

2.33.1 Cement type and content 47

2.33.2 Fly ash addition 48 2.33.3 Sulphate type and concentration ……………….…..….48 2.33.4 Chloride Ions 48

2.33.5 Control of sulphate attack 48

2.34 Acid, carbonation, chloride attack & freeze-thaw effect ……………..49

2.34.1 Acid attack 49 2.34.2 Carbonation 50 2.34.3 Carbonation of concrete 50 2.34.4 Chloride attack 51 2.34.5 Freeze & thaw attack 52

2.34.6 Prevention 53 2.35 Cracks in concrete ……………………………………………………53

2.35.1 Plastic shrinkage cracks 53 2.35.2 Measures to reduce-eliminate plastic shrinkage cracks 54 2.35.3 Plastic settlement cracks 54 2.35.4 Thermal shrinkage cracks 54 2.35.5 TSC in mass concrete due to heat of hydration 55 2.35.6 Thermal expansion and shrinkage 55 2.35.7 Early cracking – mitigation strategies 56

2.36 Factors contributing for cracks in concrete 56 2.37 Fire and concrete structures ……………………………………..…..57

2.37.1 Introduction 57 2.37.2 Effect of fire on building materials 58

2.37.3 Concrete 59

2.37.4 Steel 60

2.38 Fire resistance rating ……………………………………………..……61 2.39 Fire endurance of structures 61

2.40 ASTM e119 standard fire test 61 2.41 Advanced analytical models 63 2.42 ACI 216 method ………………………………………………………..….63 2.43 Thickness requirements 65

2.44 Conclusion 64

UNIT - 3

3.1 Cracking in bricks and brickwork 66 3.2 Structural cracking of brickwork 66 3.3 Cracks in brick faces / Fire cracks 66 3.4 Cracking in concrete walls …………………………………..……..67

3.5 Causes of cracks 67 3.6 Types of cracks 67 3.7 When should you be concerned? 68 3.8 Houses have cracks 68 3.9 Shrinkage cracks 68 3.10 Horizontal cracks in a basement foundation wall ……………………..69 3.11 Settlement cracks 69

3.11.1 Settlement crack size 69 3.11.2 Direction of movement 70 3.11.3 Repaired and re-cracked 70

3.12 Concrete slab surface defects: Causes, Prevention, Repair ……….70 3.13 Blisters 70 3.14 Cracking 73 3.15 Cracking in concrete 74 3.16 Crazing 75 3.17 Curling 76 3.18 Delamination …………………………………………………..……….77 3.19 Discoloration 78 3.20 Dusting 81 3.21 Efflorescence 82 3.22 Low spots 83

3.23 Popouts 84 3.24 Scaling and mortar flaking 87 3.25 Spalling 89 3.26 Thin toppings and underlayments ………………………………………..92 3.27 Analysis of surface defects 92 3.28 Structural and Non structural Cracks – Introduction 93 3.29 Shrinkage cracking 93

3.29.1 Cracking due to reinforcement corrosion 93 3.29.2 Cracking due to drying during the curing 93 3.29.3 Types and location of structural cracks 94 3.29.4 The cracks in other parts of the building 94 3.29.5 Crack positions 95 3.29.6 Crack states 96 3.29.7 Crack port in a horseshoe …………………………………96

3.30 Crack study and discussion 97 3.31 Conclusion 98 3.32 Cracking in concrete walls 99 3.33 Causes of cracks …………………………………………………………….99 3.34 Types of cracks 99 3.35 Minimizing the problem 99 3.36 When should you be concerned 100

UNIT – 4

4.1 Repair of Concrete 103

4.1.1 Maintenance of Concrete 103 4.1.2 General Requirements for Quality Repair …………………….104 4.1.3 Workmanship 104 4.1.4 Procedure 105

4.1.5 Materials 105 4.2 Concrete Repair System 106

4.2.1 Determine the Cause(s) of Damage …………………………107 4.2.2 Evaluate the Extent of Damage 109 4.2.3 Evaluate the Need to Repair 109 4.2.4 Select the Repair Method 109 4.2.5 Prepare the Old Concrete for Repair …………………………110 4.2.6 Concrete Removal 111

4.2.7 Reinforcing steel Preparation 112 4.2.8 Maintenance of Prepared area 112 4.2.9 Apply the Repair Method 113

4.3.10 Cure the Repair Properly 113

4.3 Causes of Damage to Concrete …………………………………………..114

4.3.1 Excess Concrete Mix Water 114 4.3.2 Faulty Design 115 4.3.3 Construction Defects 116 4.3.4 Sulfate Deterioration 117 4.3.5 Alkali-Aggregate Reaction 118 4.3.6 Deterioration Caused by Cyclic Freezing and Thawing …..119 4.3.7 Abrasion-Erosion Damage 120 4.3.8 Cavitation Damage 120 4.3.9 Corrosion of Reinforcing Steel 121 4.3.10 Acid Exposure …………………………………………………...122 4.3.11 Cracking 133 4.3.12 Structural Overloads 124 4.3.13 Multiple Causes of Damage 125

4.4 Standard Methods of Concrete Repair ………………………………….125

4.4.1 Surface Grinding 126

4.4.2 Portland Cement Mortar 126

4.4.2.1 Preparation 127 4.4.2.2 Materials 127 4.4.2.3 Application 127 4.4.2.4 Curing 127

4.5 Dry Pack and Epoxy-Bonded Dry Pack ………………………………….128

4.5.1 Preparation 128 4.5.2 Materials 129

4.5.3 Application 130 4.5.4. Curing and Protection 130

4.6 Preplaced Aggregate Concrete …………………………………………..130

4.6.1 Preparation 131 4.6.2 Materials 131 4.6.3 Application 131 4.6.4 Curing 131

4.7 Shotcrete …………………………………………………………….133

4.7.1 Preparation 134 4.7.2 Materials 134 4.7.3 Application 135 4.7.4 Curing 135

4.8 Replacement Concrete ……………………………………………………135

4.8.1 Preparation 136 4.8.2 Materials 137 4.8.3 Application 138 4.8.4 Curing and Protection 139

4.9 Epoxy-Bonded Epoxy Mortar …………………………………………..140

4.9.1 Preparation 140 4.9.2 Materials 141

4.9.3 Mixing 141 4.9.4 Application 142 4.9.5 Curing 143 4.9.6 Safety 144

4.10 Epoxy-Bonded Replacement Concrete ………………………………….144

4.10.1 Preparation 144 4.10.2 Materials 144 4.10.3 Application 145

4.10.4 Curing 145 4.10.5 Safety 146

4.11 Polymer Concrete …………………………………………………..146

4.11.1 Preparation 147 4.11.2 Materials 147 4.11.3 Application 147 4.11.4 Curing 148 4.11.5 Safety 148 4.11.6 Storage 148 4.11.7 Mixing and Handling 148 4.11.8 Personal protective equipment 148

4.12 Thin Polymer Concrete Overlay ………………………………….149

4.12.1 Preparation 149 4.12.2 Materials 149 4.12.3 Mixing Sequence 150 4.12.4 Application 150 4.12.5 Curing and Protection ………………………………….150 4.12.6 Safety 150 4.12.7 Storage 150 4.12.8 Mixing and Handling 151

4.12.9 Personal protective equipment 151

4.13 Resin Injection 151 4.14 Epoxy Resins 151 4.15 Polyurethane Resins ……………………………………………………152

4.15.1 Preparation 152 4.15.2 Materials 152 4.15.3 Injection Equipment 153 4.15.4 Application 153

4.16 Application of Epoxy Resin by Pressure Injection 154 4.17 Application of Polyurethane Resin by Pressure Injection …………….154 4.18 Cleanup 155 4.19 High Molecular Weight Metacrylic Sealing Compound 155

4.19.1 Preparation 156 4.19.2 Materials 156 4.19.3 Application 157 4.19.4 Curing and Protection 157 4.19.5 Safety 158

4.20 Polymer Surface Impregnation …………………………………………..158 4.21 Silica Fume Concrete 158

4.21.1 Preparation 159 4.21.2 Materials 159 4.21.3 Application 160 4.21.4 Curing 160 4.21.5 Safety 160

4.21 Alkyl-Alkoxy Siloxane Sealing Compound ……………………………….161

4.21.1 Preparation 161 4.21.2 Materials 161 4.21.3 Application 161

4.21.4 Curing 162 4.21.5 Safety 162

4.23 Use of Nonstandard Repair Methods 162

UNIT-5

5.1 Mechanism of Corrosion 163 5.2 Mechanisms in Concrete Deterioration by Corrosion of Embedded Steel 163 5.3 Carbonation 165 5.4 Chloride attack 165 5.5 Corrosion of Steel in Concrete 165 5.6 Reinforced Concrete in Dry conditions …………………………………167 5.7 Cathodic Protection Fundamentals 169 5.8 Waterproofing of Water Retaining Structures 172 5.9 Design Consideration & Precautions 172 5.10 Expansion and Contraction Joints 173 5.11 Polysulphides (PS) Sealant at Expansion and Contraction Joints …173 5.12 Construction Joints 174 5.13 Treatment at Fixtures like Pipes & Conduits 174 5.14 Waterbar 176 5.15 Waterproofing System - General Features 177 5.16 Selection of Waterproofng Material 178 5.16 Application on Raft Slab and External Walls …………………………179

5.16.1 Surface Preparation 179 5.16.2 Priming 179

5.17 Application on PCC Below Raft Slab 179 5.18 Application on Retaining Wall ………………………………….179 5.19 Conclusion 180