STRUCTURE REHABILITATION MANUAL

POLICY, PLANNING AND STANDARDS DIVISION ENGINEERING STANDARDS BRANCH BRIDGE OFFICE MINISTRY OF TRANSPORTATION ISBN 0-7794-6430-3 Queens Printer for Ontario, April 2004. Reproduced with permission.

To all users of this publication: The information contained herein has been carefully compiled and is believed to be accurate at the date of publication. Freedom from error, however, cannot be guaranteed. Enquires regarding the purchase and distribution of this manual should be directed to: Publications Ontario By telephone: 1-800-668-9938 By fax: (613) 566-2234 TTY: 1-800-268-7095 Online: www.publications.gov.on.ca Enquires regarding amendments, suggestions, or comments should be directed to the Ministry of Transportation at (905) 704-2065.

CONTINUING RECORD OF REVISIONS MADE TO THE MANUAL

STRUCTURE REHABILITATION MANUAL

This sheet should be retained permanently in this page sequence in the Manual. All revised material should be inserted as soon as received and the relevant entries made by hand in the spaces provided to show who incorporated the Revision and the date it was done. If this practice is followed faithfully, it will be a simple matter to tell whether or not this copy of the Manual is up to date since all future Revisions will be numbered and dated.

Revision No. Date

Entered By Date

THIS REPRINT INCLUDES REVISION #9

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CONTENTS PREFACE ACKNOWLEDGEMENTS FOREWORD PART 1: CONDITION SURVEYS PART 2: REHABILITATION SELECTION PART 3: CONTRACT PREPARATION PART 4: CONSTRUCTION

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PREFACE The Bridge Deck Rehabilitation Manual was first published in 1983 and consisted of two parts: Part One, Condition Surveys and Part Two, Contract Preparation. In 1988, the Structure Rehabilitation Manual was published to supersede the Bridge Deck Rehabilitation Manual and included procedures for the condition survey and rehabilitation of all above-grade concrete components of highway bridges. It was issued in loose-leaf format to facilitate updating. Since then, the manual has undergone several minor revisions in various parts. The last revision was issued in 1996 as Revision No. 8. The present revision, Revision No. 9 of the Structure Rehabilitation Manual, is a complete rewrite of the entire manual and has incorporated many recent changes in the condition survey requirements in Part 1. Part 2 has been revised to include some of the recently developed rehabilitation treatments, for example, electrochemical chloride extraction and passive cathodic protection systems. It is also necessary to update Part 3 for the changes in special provisions and tender items.

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ACKNOWLEDGEMENTS Staff from Concrete Section and the regional structural sections have provided many input and review comments for the draft and are gratefully acknowledged. Special acknowledgement is also given to Rita Goulet for the formatting and editing of the tables and sketches. Revision No. 9 of the Structure Rehabilitation Manual has been prepared by: David Lai, Head Rehabilitation Engineer Naran Patel, Senior Rehabilitation Engineer

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FOREWORD The Structure Rehabilitation Manual covers the procedures in the preparation of contract documents for the rehabilitation of various structure components. The manual is written primarily for Ministry projects, but may also be used by Municipalities and Consulting Engineers engaged in structure rehabilitation. This manual is divided into four parts that reflect the following steps of structure rehabilitation: PART 1 - Condition Surveys PART 2 - Rehabilitation Selection PART 3 - Contract Preparation PART 4 - Construction Part 1, Condition Surveys, describes how condition surveys are to be carried out. Appendices 1A to 1E include consultant agreements, standard forms and standard legends. Condition surveys are normally carried out by consultants. Recommendations for the rehabilitation and contract documents may be prepared in-house or by a consultant. Other authorities, especially municipalities, frequently engage consultants to carry out the condition survey, make recommendations for repair, prepare the contract documents and supervise the construction. Occasionally, all the activities may be carried out by one consultant, but frequently, two or more consultants will be involved. The scope of the work needs to be clearly defined in the agreement with the consultant. Part 2, Rehabilitation Selection, describes methods of rehabilitation and shows how the information collected in the condition surveys is used to select the most appropriate method of rehabilitation for each different type of structure component. Although structural analysis is outside the scope of this manual, structure rehabilitation cannot be separated from an evaluation of the load carrying capacity of the structure. Therefore, before preparing the contract documents, the structure may have to be evaluated to ensure that all elements of the structure can support any additional loading and temporary loading conditions resulting from the rehabilitation. Part 3, Contract Preparation, covers most of the activities likely to be encountered in rehabilitation contracts. Only some of these activities will be included in any one contract. Consequently, considerable care is required in ascertaining what specific items are appropriate to the job in hand. Sample special provisions and reference drawings which can be used as a guide in preparing contract documents are to be developed and will be inserted in the Appendix to Part 3 in the future. Part 4, Construction, summarizes the construction procedures used for each of the rehabilitation or repair methods included in the manual. This part is to be developed in the future. It is expected the more experienced designer will use Part 4 for reference purposes only.

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The information contained in this manual is based on the Ministrys Research and Development reports and Bridge Office reports published since 1975, as well as the Ministrys experience in preparing and administering structure rehabilitation contracts. No attempt has been made to summarize research results. The interested reader is referred to the Ministrys research reports and the numerous references listed in them. The Ministrys Bridge Office or Concrete Section should be contacted for additional advice and guidance for rehabilitations not covered in this manual.

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PART 1

CONDITION SURVEYS

CONTENTS

1. INTRODUCTION .............................................................................................. 1-1 1.1 General ..................................................................................................... 1-1

1.1.1 Detailed Visual Inspection............................................................ 1-1 1.1.2 Detailed Condition Survey ........................................................... 1-1 1.1.3 Dart Survey................................................................................... 1-2

1.2 Common Defects in Materials .................................................................. 1-3 1.3 Protective Treatments for Structures in Ontario........................................ 1-3

1.3.1 General ......................................................................................... 1-3 1.3.2 Superstructures ............................................................................. 1-4 1.3.3 Substructures ................................................................................ 1-5

1.4 Concrete Removal and Abrasive Blast Cleaning Policies........................ 1-6 2. REQUIREMENTS FOR DATA COLLECTION, SAMPLING AND TESTING .................................................................................................. 1-7

2.1 General ..................................................................................................... 1-7 2.2 Delamination and Surface Deterioration Survey....................................... 1-7

2.2.1 Bridge Decks ................................................................................ 1-7 2.2.2 Concrete Components, Excluding Bridge Decks........................... 1-7

2.3 Corrosion Potential Survey....................................................................... 1-8 2.3.1 Bridge Decks ................................................................................ 1-8 2.3.2 Concrete Components, Excluding Deck Slabs .............................. 1-8

2.4 Concrete Cover Survey............................................................................. 1-8 2.4.1 Bridge Decks ................................................................................ 1-8 2.4.2 Concrete Components, Excluding Deck Slabs .............................. 1-9

2.5 Expansion Joint Survey............................................................................. 1-9 2.6 Concrete Coring and Testing .................................................................... 1-9

2.6.1 Bridge Decks ................................................................................ 1-9 2.6.2 Concrete Components Excluding Bridge Decks............................ 1-9

2.7 Asphalt Sawn Samples and Large Asphalt Strips ................................... 1-10 2.8 Grid Layout............................................................................................. 1-10 2.9 Detailed Visual Inspections .................................................................... 1-11 2.10 Inspection of Cathodic Protection Embedded Hardware........................ 1-11 2.11 Conductive Asphalt Resistivity Test....................................................... 1-11 2.12 Investigation of Fire Damaged Concrete................................................. 1-11

3. PLANNING THE CONDITION SURVEY..................................................... 1-12

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3.1 General ................................................................................................... 1-12 3.2 Sampling and Data Collection................................................................ 1-12 3.3 Plans and Previous Inspections............................................................... 1-12 3.4 Site Visit................................................................................................. 1-13 3.5 Traffic Control........................................................................................ 1-13 3.6 Manpower .............................................................................................. 1-14 3.7 Grid Layout............................................................................................. 1-14

3.7.1 General ....................................................................................... 1-14 3.7.2 Post-Tensioned Decks with Circular Voids................................ 1-15

3.8 Equipment............................................................................................... 1-15 3.8.1 General ....................................................................................... 1-15 3.8.2 General Tools and Materials ...................................................... 1-15 3.8.3 Additional Tools and Materials for Asphalt Covered Deck....... 1-17 3.8.4 Tools and Materials For Resistance Test ................................... 1-17

3.9 Forms...................................................................................................... 1-17 4. FIELD PROCEDURES .................................................................................... 1-18

4.1 General ................................................................................................... 1-18 4.2 Detailed Visual Inspection...................................................................... 1-18 4.3 Detailed Condition Surveys.................................................................... 1-18

4.3.1 General ....................................................................................... 1-18 4.3.2 Photographs ................................................................................ 1-18 4.3.3 Traffic Control............................................................................ 1-19 4.3.4 Grid Layout................................................................................. 1-19 4.3.5 Cathodically Protected Components ........................................... 1-19 4.3.6 Equipment Calibration................................................................ 1-19 4.3.7 Corrosion Potential Survey......................................................... 1-19

4.3.7.1 Technique ....................................................................... 1-20 4.3.7.2 Procedure for Concrete with Uncoated Reinforcing Steel ............................................ 1-20 4.3.7.3 Procedure for Concrete with Epoxy Coated Reinforcing Steel ............................................................ 1-22

4.3.8 Concrete Cover Survey............................................................... 1-22 4.3.8.1 Technique ....................................................................... 1-22 4.3.8.2 Procedure ....................................................................... 1-23

4.3.9 Delamination Survey .................................................................. 1-23 4.3.9.1 Technique ...................................................................... 1-23 4.3.9.2 Procedure ....................................................................... 1-24

4.3.10 Concrete Surface Deterioration Survey...................................... 1-24 4.3.11 Expansion Joint Survey - Bridge Decks...................................... 1-25 4.3.12 Drainage - Bridge Decks ............................................................ 1-26 4.3.13 Concrete Cores........................................................................... 1-27

4.3.13.1 General ........................................................................... 1-27 4.3.13.2 Bridge Decks Riding Surface ......................................... 1-27 4.3.13.3 Curbs, Sidewalks, Barrier Walls and Approach Slabs... 1-30 4.3.13.4 Concrete Components, Excluding Bridge Decks............. 1-30 4.3.13.5 Repairs to Core Holes and Epoxy Coated Rebar............ 1-30

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4.3.14 Asphalt Sawn Samples ............................................................... 1-31 4.3.15 Removal of Large Asphalt Strips................................................ 1-32

4.3.16 Inspection of Cathodic Protection Embedded Hardware............ 1-33 4.3.17 Conductive Asphalt Resistance Test (Cathodic Protection) ....... 1-34

4.4 Sequence of Operations .......................................................................... 1-34 4.4.1 General ....................................................................................... 1-34 4.4.2 Exposed Concrete Components and Exposed Decks .................. 1-35 4.4.3 Bridge Decks with Asphalt Wearing Surface ............................. 1-35

5. LABORATORY TESTING OF CORES ........................................................ 1-37

5.1 Photographs and Description.................................................................. 1-37 5.2 Physical Testing of Concrete .................................................................. 1-37

5.2.1 Compressive Strength................................................................. 1-39 5.2.2 Chloride Content......................................................................... 1-39 5.2.3 Air Void System......................................................................... 1-39

5.3 Resistivity Testing of Conductive Asphalt (Cathodic Protection) .......... 1-40 5.4 Significance of Test Results ................................................................... 1-40

5.4.1 Compressive Strength................................................................. 1-40 5.4.2 Air Content ................................................................................. 1-40 5.4.3 Chloride Content......................................................................... 1-40 5.4.4 Conductive Asphalt Resistivity (Cathodic Protection) ............... 1-42

5.5 Retention of Samples.............................................................................. 1-42 6. THE REPORT .................................................................................................. 1-43

6.1 Introduction............................................................................................. 1-43 6.2 Contents .................................................................................................. 1-43 6.3 Standard Forms....................................................................................... 1-43

6.3.1 Guide to Completing the Standard Forms ................................... 1-44 6.3.1.1 Structure Identification Sheet.......................................... 1-44 6.3.1.2 Detailed Condition Survey Summary Sheets................... 1-44

6.4 Text......................................................................................................... 1-45 6.5 Photographs ............................................................................................ 1-46 6.6 Drawings - Detailed Condition Survey................................................... 1-46

6.6.1 Requirements for All Concrete Components............................... 1-46 6.6.2 Exposed Concrete Components (Excluding Decks).................... 1-46 6.6.3 Exposed Concrete Decks ............................................................ 1-47 6.6.4 Asphalt-Covered Decks.............................................................. 1-47

7. REVIEW OF THE REPORT........................................................................... 1-49

7.1 Introduction............................................................................................. 1-49 7.2 Reference Data ....................................................................................... 1-49 7.3 Structure Identification Sheet.................................................................. 1-49 7.4 Summary of Significant Findings ............................................................ 1-49

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7.5 Detailed Condition Survey Summary Sheet(s)........................................ 1-50 7.5.1 Dimensions ................................................................................. 1-50 7.5.2 Cracking ..................................................................................... 1-50 7.5.3 Scaling........................................................................................ 1-51 7.5.4 Concrete Air Entrainment and Compressive Strength................. 1-51 7.5.5 Delamination and Spalling.......................................................... 1-51 7.5.6 Concrete Cover........................................................................... 1-51 7.5.7 Corrosion Potential..................................................................... 1-52 7.5.8 Adjusted Chloride Content at Rebar Level................................. 1-52 7.5.9 Defective Cores and Sawn Samples........................................... 1-53 7.5.10 Asphalt and Waterproofing......................................................... 1-53 7.5.11 Underside Deterioration (Deck Condition Surveys)................... 1-53 7.5.12 Expansion Joints (Deck Condition Surveys)............................... 1-54 7.5.13 Drainage (Deck Condition Surveys)........................................... 1-54

7.6 Survey Equipment and Calibration Procedures ..................................... 1-54 7.7 Core Log................................................................................................. 1-55 7.8 Sawn Samples (asphalt covered decks only).......................................... 1-56 7.9 Cathodic Protection Testing Summary Sheet .......................................... 1-56 7.10 Photographs ............................................................................................ 1-56 7.11 Drawings ................................................................................................ 1-56 7.12 OSIM Forms/OSIMS Output................................................................... 1-57 7.13 Acceptance of the Report........................................................................ 1-57 7.14 Maintenance Prior to Rehabilitation....................................................... 1-57

8. REFERENCE PUBLICATIONS ..................................................................... 1-58

8.1 Ministry's Publications ........................................................................... 1-58 8.2 Non-Ministry Reference Publications..................................................... 1-58

APPENDICES 1A STANDARD CONSULTANT'S AGREEMENT FOR DETAILED CONDITION SURVEYS 1B GRID LAYOUTS 1C STANDARD FORMS 1D STANDARD LEGEND 1E CALCULATING AC RESISTANCE OF EPOXY COATED REBAR

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1. INTRODUCTION 1.1 General Condition Surveys involve carrying out a detailed visual inspection of the structure and detailed condition surveys of the various structure components. The purpose of the surveys described herein is to determine and document the deterioration in the structure so as to establish the type of rehabilitation and prepare contract documents. It may also provide information for an evaluation of the load carrying capacity of the bridge as described in the Canadian Highway Bridge Design Code, CHBDC, (2). Condition surveys shall be carried out with a plan for worker safety, and safety to the travelling public, and shall follow the guidelines given in Safety Practices for Structure Inspections(3) and comply with the Occupational Health and Safety Act 1.1.1 Detailed Visual Inspection A detailed visual inspection of all components according to the procedures given in the Ontario Structure Inspection Manual, OSIM (4), may be required, to determine if repairs of these components should be included in the rehabilitation contract. However, caution should be exercised when assessing the overall condition of the component using visual inspections as the visual observations do not reveal hidden defects or deterioration in concrete such as delaminations, rebar corrosion and low concrete cover to reinforcing steel. 1.1.2 Detailed Condition Survey A detailed condition survey is generally carried out only after a concrete component has been identified for rehabilitation. The data collected is then used to establish the rehabilitation method and to prepare contract documents. The procedure for carrying out a detailed condition survey involves the observation and recording of surface defects and may also involve a delamination survey, a cover meter survey, a corrosion potential survey, coring of concrete components, asphalt sawn samples and physical testing of the concrete cores. Components that require rehabilitation are identified by the Regional Structural Sections in their routine detailed inspection reports, or in general inspections. Procedures for routine detailed inspections are given in the Ontario Structure Inspection Manual, OSIM (4). The need for structure rehabilitation is usually driven by the condition of the bridge deck. As most of the bridge decks have an asphalt-wearing surface, it is usually difficult to assess the condition of the concrete beneath the asphalt during an OSIM inspection. Therefore, candidates for a detailed condition survey should include the top surface of deck slabs included in paving contracts that have not been rehabilitated in the last 15 years. The scope of the detailed condition survey should be expanded to include other structure components such as piers, abutments and barrier walls when the OSIM inspection indicates that these components have deteriorations and a detailed condition survey is warranted. Detailed condition survey of a component may not be

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necessary if the need for replacement of a structurally deficient component is established by an evaluation of the load carrying capacity or by other means. The detailed condition survey usually should not be carried out on bridge decks containing epoxy coated steel that have been constructed in the last 20 years as these decks should still be in good condition. A Ground Penetrating Radar (GPR)(5) survey followed by a detailed condition survey should still be considered for these bridges if the asphalt wearing surface and deck soffit show signs of significant deterioration in more than 5% of the deck area. In the future, bridges requiring detailed condition surveys will be identified by the Ontario Bridge Management System program based on condition states of different components of the bridge. However, the program would allow the user to override any recommendations that the program recommends if they seem inappropriate. The detailed condition survey should preferably be carried out no more than two years prior to the proposed rehabilitation. Where a project is deferred, so that the detailed condition survey for bridge decks is more than four years old at time of construction, it would be necessary to update the original survey. Sufficient additional information should be gathered to update tender quantities and to ensure that the most effective method of repair is recommended. For exposed concrete components such as barrier walls, abutments and piers, the concrete delamination survey should be updated the year before construction for the portion of the components that are exposed to chlorides. 1.1.3 Ground Penetrating Radar Survey Deck Assessment by Radar Technology used to be conducted by the Ministry's Bridge Office until 1998 when it was outsourced. Currently GPR survey is conducted by consultants specialising in radar technology. GPR can be used on asphalt covered decks to detect scaling, debonding, delaminations, concrete cover to reinforcing steel and asphalt thickness; it should not be performed on wearing surface containing steel slag. The older type of GPR previously used by the Ministry did not always reflect accurately the physical condition of the deck. The Ministry is currently investigating a new portable type of GPR that may provide more accurate results. If GPR survey is to be conducted, it should normally be carried out prior to the detailed condition surveys, especially on decks constructed with epoxy coated reinforcing steel. In order to minimize the survey cost per bridge, candidate bridges in the same region should be grouped in the same consultants assignment. The data from GPR surveys should be used to: Supplement data from visual and preliminary investigations to determine which asphalt

covered decks should be rehabilitated; Determine the location of concrete cores and sawn samples during the detailed condition

survey; Supplement data from detailed condition surveys for asphalt covered decks to finalise

selection of rehabilitation method and to improve the design estimate for tender item quantities.

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1.2 Common Defects in Materials The defects and deterioration that commonly occur in the materials used in structures are described in Ontario Structure Inspection Manual, OSIM.( 4) Common defects in waterproofing membranes not covered by OSIM are, described below: inadequate thickness at time of construction; excessive thickness resulting in shoving of the pavement; lack of adhesion to the bridge deck or asphalt; moisture present beneath the waterproofing; penetration of the membrane by aggregate from the bituminous overlay; migration of the membrane into the bituminous overlay; rotting of the fibreglass in some fibreglass-asphalt emulsion systems; embrittlement in mastic waterproofing. 1.3 Protective Treatments for Structures in Ontario 1.3.1 General The type of protective treatments varied over the years. Changes in standards have resulted in some structures being prone to certain types of deterioration. Consequently, there is often a relationship between the age of a structure and its condition. The type of protective treatments are summarised in the subsections below. Since the time between design and construction varies, there may be some overlap between the dates and the construction methods. The dates for waterproofing are for original construction. Most of the deck slabs built before 1973 have since been rehabilitated as part of a highway resurfacing contract and are now waterproofed with hot rubberised asphalt or mastic waterproofing membrane. It should be noted that prior to 1988 waterproofing membrane was not always installed to the minimum thickness requirements and in some cases was installed over an excessively rough surface. Since 1988, the quality of the waterproofing membrane installation should have improved as acceptance is now based on a statistical approach according to end result specification and remedial measures have been implemented for repairing rough concrete surfaces to a surface acceptable for waterproofing. Occasionally, highways were resurfaced without removing the existing asphalt and a considerable build up of asphalt on older decks is not uncommon. 1.3.2 Superstructures

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Constructed Prior to 1958 The deck slabs were not waterproofed at the time of construction. The concrete was not air-entrained. These decks are prone to salt penetration and to severe scaling due to freeze-thaw action. The condition of these older deck slabs varies considerably. Constructed Between 1958 and 1961 The concrete was specified to be air-entrained but the admixtures used did not produce a good air void system and the control of air content was poor. Many deck slabs were treated with silicone prior to the paving but this was not effective in preventing salt penetration. These decks are also prone to salt penetration and to scaling but their condition is generally better than pre-1958 structures. Constructed Between 1962 and 1964 Deck slabs were waterproofed using mastic asphalt or glass fibre in an asphalt emulsion. Most membranes were ineffective after a few years in service. The concrete was air-entrained but the control on air content was not good. The condition of the decks is variable, but is generally fair to good. As there is no waterproofing treatment for the parapet walls, the parapet walls with low cover and severe exposure to chlorides are likely in poor condition. Constructed Between 1965 and 1972 The decks were built with exposed concrete wearing surface and minimum cover to reinforcing steel was specified to be 40 mm, but the cover requirement was generally not met. Most decks exhibit corrosion induced distress. The concrete was generally properly air-entrained and of good quality. Many of these decks have now been waterproofed and paved. However, waterproofing and asphalt paving on these decks may now be due for replacement. As there is no waterproofing treatment for the concrete barrier walls, the barrier walls with low cover and severe exposure to chlorides are likely in poor condition. Constructed 1973 to 1978 The deck slabs were waterproofed with a rubberised asphalt waterproofing membrane. Mastic asphalt was used on some rigid frames throughout the period and also on other types of structures

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until about 1976. A protection board was used with rubberised asphalt after 1975. Most decks are in good condition. As there is no waterproofing treatment for the concrete barrier walls, the barrier walls with low cover and severe exposure to chlorides are likely in poor condition. Constructed After 1978 The decks contain epoxy coated reinforcing bars as the top mat of steel and are waterproofed with rubberised asphalt membrane and protection board. Rigid Frame structures, waterproofed before 1986, might be waterproofed with either mastic or asphalt membrane waterproofing. The curbs and barrier walls also contain epoxy coated reinforcing steel. Specified cover is 70 + 20 mm. The decks are in good condition. As there is no waterproofing treatment for the concrete barrier walls, the barrier walls with low cover and severe exposure to chlorides may begin to exhibit some corrosion induced deterioration after 25 years in service despite the presence of epoxy coated reinforcing steel. Constructed After 1999 MTO began to use stainless steel for top reinforcement in decks carrying strategic highways with 100,000 AADT or more. Other superstructure components with direct salt splash ( barrier walls, sidewalks and expansion joint dams) also used stainless steel. High performance concrete also began to be used on selective structures while keeping the epoxy coated rebars. In all cases, rubberised asphalt waterproofing membrane and protection board continued to be used. 1.3.3 Substructures Constructed Prior to 1958 The concrete was not air-entrained. The elements directly exposed to salt splash and/or roadway drainage are prone to spalling due to corrosion of reinforcing steel and to scaling due to freeze-thaw action. The quality of concrete was highly variable due to poor construction practices and high water cement ratio. Constructed Between 1958 and 1964 The concrete was air-entrained but the admixtures did not always produce a good air void system and control of air content was poor. The substructure is prone to scaling due to freeze-thaw action and spalling in areas exposed to chloride but the condition is generally better than pre-1958 structures. Constructed Between 1965 to 1981

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The concrete was generally properly air-entrained and of good quality. The resistance to scaling is good but the areas exposed to salt splash and roadway drainage are still prone to spalling due to the corrosion of the reinforcement. Constructed After 1981 All reinforcing steel within 100 mm of a concrete surface directly exposed to salt splash and/or roadway drainage is epoxy coated. Reinforcing steel in areas that are indirectly exposed to salt, generally, through windblown roadway spray is uncoated. This reinforcing steel is considered to be adequately protected through the use of increased concrete cover and the designation of 30 MPa concrete in place of the 20 MPa concrete sometimes specified. Concrete aggregates in these structures have been tested for alkali reactivity and, therefore, possibility of alkali-aggregate reaction is remote. The substructures are in good condition. Constructed After 2000 Pier columns and shafts within splash zones ( less than 10 m from travelled lanes, and/or under expansion joints ) used stainless steel reinforcement. Structures that were selected for high performance concrete would have used HPC for all substructure components, except the footings. Epoxy coated reinforcement continued to be used for other substructure components. 1.4 Concrete Removal and Abrasive Blast Cleaning Policies The performance of past rehabilitation treatments are also related to the policies that were in effect at the time of rehabilitation. Prior to 1987, abrasive blast cleaning reinforcing steel was specified with no acceptance criteria. The current requirement of a commercial blast cleaned finish has been specified since 1987. Prior to 1989, the policy was to remove concrete 25 mm below the reinforcing steel only in areas where more than 50% of the circumference of the rebar was exposed. The policy since 1989 has been to remove concrete to a uniform depth of 25 mm below the first layer of reinforcing steel and 25 mm locally around the second layer wherever reinforcing steel is exposed, and within spalled and delaminated areas. Also in 1989, the policy for concrete removal on bridge decks was changed to include removal of sound concrete in areas with corrosion potential more negative than 0.35 volts. This policy has generally not been applied to other components. However, in some cases, removal by corrosion potential criteria may have been specified for other components if the cause of chloride exposure cannot be eliminated and it is felt that concrete will continue to delaminate at a high rate if the high corrosion potential concrete is not removed.

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2. REQUIREMENTS FOR DATA COLLECTION, SAMPLING AND TESTING

Section 2 gives guidelines for the preparation of the consultant agreement for the condition surveys. 2.1 General The requirements for sampling and collecting data in the field and the number and type of tests to be performed in the laboratory on the samples taken, may vary from component to component for a variety of reasons. Guidelines are given in this section to assist in determining these requirements and in preparing the Consultant's Agreement. The type and extent of data to be collected and the requirements for the testing of samples shall be specified in the Consultant's Agreement. When detailed condition surveys of extremely large bridge decks (> 4000 m2) are required, consideration should be given to limiting the cores and sawn samples to a representative portion(s) of the deck. When access or traffic protection is a major consideration for detailed condition surveys of soffits and substructures, the survey could be limited to the area(s) where major deterioration is expected. 2.2 Delamination and Surface Deterioration Survey 2.2.1 Bridge Decks A detailed condition survey of a reinforced concrete bridge deck shall always include a survey of the material defects and deterioration in the wearing surface (concrete or asphalt) and the deck soffit. In addition, a delamination survey shall also be carried out on all exposed concrete wearing surfaces of the bridge deck, curbs, medians, sidewalks, inside faces of concrete barrier/parapet walls and expansion joint end dams. A delamination survey should also be carried out on the deck soffit when more than 10% of the soffit, or more than 10 square metres is exhibiting deterioration and it is anticipated that major concrete repairs will be required. Deck soffit areas susceptible to deterioration include end of deck under expansion joints, areas adjacent to construction joints, cantilever edges and areas under round voids in post-tensioned structures. 2.2.2 Concrete Components, Excluding Bridge Decks A delamination and concrete surface deterioration survey shall be carried out on all exposed concrete components that require concrete rehabilitation. If repairs to cracks using injection techniques are anticipated, the surface deterioration survey should also include measuring the depth of medium and wide cracks by coring. 2.3 Corrosion Potential Survey

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2.3.1 Bridge Decks The detailed condition survey for reinforced concrete deck surfaces with black reinforcing steel shall always include a corrosion potential survey. Normally a corrosion potential survey is not carried out on the deck soffit; however, a limited survey should be carried out in areas where the deck soffit is deteriorating due to leaking expansion joints, construction joints, salt splash, and where a delamination survey would be carried out as mentioned in 2.2.1. A corrosion potential survey shall also be carried out on the inside concrete faces of concrete barrier systems, curbs, sidewalks and medians where significant spalling and corrosion staining has been observed. On bridge decks with epoxy coated reinforcing steel, the regular type half-cell survey cannot be carried out as usually there is no electrical continuity between the different reinforcing bars. However, the half-cell readings should be taken at core and sawn sample locations where the rebar ground connection and the half-cell reading are at the same rebar. Along with localised half-cell readings, AC resistance measurements should be taken to assess the condition of the epoxy coating. On bridge decks that are cathodically protected with a conductive asphalt system, the corrosion potential survey shall be limited to the locations of the sawn samples as the conductive asphalt would affect the readings obtained at the drill hole locations. The cathodic protection system should be de-energised for a minimum of four weeks prior to the commencement of the survey to allow the reinforcing steel to depolarise. 2.3.2 Concrete Components, Excluding Deck Slabs A corrosion potential survey should be carried out on piers and abutments that exhibit deterioration (spalling, delamination, rust-stained cracks etc.) for at least 10% of the total component area. Typically these components are located under open expansion joints, joints that are leaking and in areas where these components are exposed to salt splash. The survey can be limited to the area of chloride exposure. 2.4 Concrete Cover Survey 2.4.1 Bridge Decks A cover meter survey shall be carried out for all exposed concrete bridge decks as part of the detailed condition surveys (excluding update surveys). The concrete cover survey should also be specified for concrete curbs, sidewalks, median and the inside faces of concrete barrier/parapet walls, and for deck soffit where corrosion potential survey has been specified. For asphalt covered decks, concrete cover survey shall be carried out at the sawn samples and large asphalt strips removal. 2.4.2 Concrete Components, Excluding Deck Slabs

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A concrete cover survey should be carried out on components that exhibit deterioration for at least 10% of the component area. Deterioration could be a combination of delaminations, rust stains and cracking on the surface, or spalls with exposed reinforcing steel. The cover meter readings may also be required to calculate tender quantities. 2.5 Expansion Joint Survey An expansion joint survey shall always be included with a first time detailed deck condition survey. In the case of update surveys, an expansion joint survey is not required if it has been completed as part of the original deck condition survey. 2.6 Concrete Coring and Testing 2.6.1 Bridge Decks Concrete coring and testing shall always be carried out when a detailed condition survey is carried out on a deck for the first time. The need for coring and testing for update surveys shall be determined on an individual basis for each structure. The diameter of the cores shall be 100 mm and the number of cores required shall be determined in the field based on Table 4.3 in Section 4. Additional cores should be specified for the following: where the rehabilitation work will involve removal of curb or sidewalk, at least one core

shall be taken from each side of the bridge to establish the quality of the bond with the deck slab;

a minimum of two core should be taken from curbs, sidewalks, medians and inside faces of barrier walls when a corrosion potential survey is specified.

unless otherwise known, one core shall be taken to establish whether a concrete approach slab is present.

If a large asphalt strip is removed for condition survey of a deck previously rehabilitated with an overlay, at least one core should be taken in an area that sounds hollow by chain drag in order to ascertain whether the overlay has debonded.

2.6.2 Concrete Components Excluding Bridge Decks The requirements for coring shall be determined on an individual basis. Normally, no more than 3 cores are required from each component. The diameter of the cores shall be 100mm. However, 25mm, 50mm and 75mm diameter cores may be specified in areas of closely spaced reinforcing steel where it is structurally undesirable to core through the reinforcing steel. The following criterion shall be used to determine the number of cores required:

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two core should be taken from the substructure for chloride analysis to determine chloride profile when a corrosion potential survey is carried out; the cores should not be specified for circular pier columns with spiral steel as these cores cannot be obtained without cutting through the spiral rebar;

for skyway type substructures, two additional cores should be taken from each pier for chloride analysis when a corrosion potential survey is carried out on the pier;

a minimum of one core shall be taken for air void determination if the surface of the component shows signs of extensive scaling and structure has been built after 1958;

a minimum of one core shall be taken to determine soundness of concrete when the surface of the component is extensively disintegrated or exhibits signs of alkali-aggregate reaction;

if crack repair work using injection techniques is anticipated, cores may be required to determine depth and orientation of the crack if this information cannot be obtained using feeler gauges or other methods. If the cracks are in the soffit of beams and where it is impractical to take cores due to the congestion of reinforcement or prestressing cables, concrete cover to the reinforcement or prestressing cables should be removed locally to ascertain their condition;

if the condition of the ballast walls are suspect, at least one core should be taken from the ballast wall to assess the condition of the concrete in areas that cannot be visually assessed.

2.7 Asphalt Sawn Samples and Large Asphalt Strips Asphalt sawn samples shall always be taken whenever a detailed condition survey is carried out on an asphalt covered deck. The number of sawn samples required shall be determined in the field based on Table 4.4 in Section 4. Removal of a large asphalt strip 1.50 m x 6.0 m shall be specified for decks based on the following guidelines: Bridges showing significant areas of leaching, cracking and wetness at soffit. Asphalt covered but no waterproofing. Large structures where change in conditions and scope of work would have a large impact. Post-tensioned decks with circular voids but without transverse post-tensioning. 2.8 Grid Layout When a detailed condition survey includes a corrosion potential survey and/or cover meter survey the data shall be collected with reference to grid points marked on the component surface. A grid layout is optional when the detailed condition survey is limited to a delamination and surface deterioration survey or in areas where it is difficult to layout a grid. 2.9 Detailed Visual Inspections

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The Regional Structural Sections should decide if the detailed visual inspection should be done by the Consultant as part of the condition survey. 2.10 Inspection of Cathodic Protection Embedded Hardware The components to be tested shall be identified by the Bridge Office and Regional Structural Section. Guidelines for assessing the performance of embedded hardware are described in the Cathodic Protection Manual for Concrete Bridges (1). The components to be tested shall be listed in the Consultant's Agreement. 2.11 Conductive Asphalt Resistivity Test When the anode AC resistance test is required on a structure protected with the conductive asphalt cathodic protection system, cores of the conductive asphalt layer should be tested for electrical resistivity. The number of cores to be tested is determined by Bridge Office and the Regional Structural Section and shall be identified in the Consultant's Agreement. The testing of the cores for electrical resistivity will be carried out by the Ministry. A two nail resistance check of the conductive asphalt shall also be taken at several locations. The number of resistance checks shall be determined by the Bridge Office and the Regional Structural Section and shall be identified in the Consultant's Agreement. 2.12 Investigation of Fire Damaged Concrete The requirements for investigating fire damaged concrete are contained in ASTM Report STP 169B, "Significance of Tests and Properties of Concrete and Concrete-Making Materials" (12). 2.13 Sampling and Testing of Asbestos Ducts When there are utility ducts embedded in the deck or sidewalk that may interfere with the rehabilitation work, the condition survey should include sampling and testing of the duct material wherever possible ( usually samples could be taken at expansion joint gap ) to confirm whether asbestos is present.

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3. PLANNING THE CONDITION SURVEY Section 3 gives guidelines for the preparations required prior to conducting a condition survey. The information in this section is to be used as a guide as the above requirements will vary with each individual project. 3.1 General Prior to carrying out the condition survey, considerable preparation is required to ensure that the field investigation will be well organised. In advance of the field investigation, pertinent features of the structure should be identified and requirements for grid layout, sampling and data collection, equipment, manpower and traffic control should be determined. Arrangements should be made at least four weeks prior to the commencement of the condition survey with District Electrical Maintenance to turn off the electrical power supply on structures that are cathodically protected. The Consultant shall also make arrangements with the District to obtain a key to open the control cabinet. The District shall be also notified after completion of the investigation to re-energise the cathodic protection system. 3.2 Sampling and Data Collection The sampling and data collection requirements of the condition survey are contained in the Consultant's Agreement; pertinent sections of a typical Consultants Agreement are given in Appendix 1A. If the Condition Survey is to be done by the Regional Structural Section staff, the sampling and data collection requirements shall be determined using the guide lines set forth in Section 2, Part 1, of this manual. 3.3 Plans and Previous Inspections/Surveys The latest version of the existing structure plans and as constructed drawings should be reviewed for the following criteria: size and type of structure; unusual features in the design; structure location and topography at the site; direction and size of top reinforcing steel bars for covermeter check; location of utility ducts; location of stressing cables and void tubes on post-tensioned structures; year of construction - relationship between age and possible deterioration as detailed in

subsection 1.3;

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number of separate grounds that will be required for potential measurements (a separate ground is required for each discontinuous slab);

details of previous rehabilitations; location of all cables, anodes, probes and reference cells on structures that are

cathodically protected. The GPR Survey and previous Detailed Condition Surveys, if available, should be reviewed to determine location of samples. Previous routine detailed inspection files should be reviewed for history of deterioration and for details of any previous repairs. A copy of the latest inspection report should be obtained from the Ontario Bridge Management System, (6). 3.4 Site Visit A preliminary visit to the site shall be made to establish: traffic control requirements; general indications of the condition of the structure which can be used to establish the

approximate duration of the survey and crew size; the extent of deterioration, including soffit condition of decks, and the need to arrange for

a boat, ladder, bucket truck or other equipment; any unusual problems. Where a Consultant is to carry out the condition survey, a reconnaissance trip may be required with Ministry staff so that the extent of inspection and sampling requirements can be generally agreed upon. 3.5 Traffic Control Traffic control for condition surveys shall be in accordance with the Ontario Traffic Manual Book 7-Temporary Condition, (7). The responsibility for provision of traffic control may vary from Region to Region but should be identified in the Standard Consultant's Agreement. The order and number of lane closures required to carry out the survey in the most expedient manner and with the least disruption to traffic shall be determined and discussed with the Regional Structural Sections and the Districts involved. The local OPP detachment should be notified in advance when lane closures are required for the condition survey. 3.6 Manpower

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In general, the crew will consist of a supervising Professional Engineer and two to four crew members. Additional personnel may be required for traffic control, concrete core drilling, and asphalt sawing operations. On large structures, the crew size may have to be increased for mapping cracks and operating additional cover meters or half-cells. If there are any time constraints involved in carrying out the survey (e.g. work permissible in off-peak hours only), they shall be identified in the Consultant's Agreement and may influence manpower requirements. 3.7 Grid Layout 3.7.1 General When carrying out a detailed condition survey that involves a corrosion potential and concrete cover survey, data is collected with reference to grid lines. A 1.5 m x 1.5 m grid is used on most bridge decks; a 3 m x 3 m grid could be used on bridge decks with an area greater than 500 m2 that were constructed in 1975 or later. A 1.0 m x 1.0 m grid is usually used on other concrete components but the size of this grid may vary depending on the dimensions of a particular component. A proposed grid layout should be established using existing structure drawings prior to going to the site. Grid lines, whether longitudinal, transverse, vertical or horizontal shall run parallel to their respective reference lines. A minimum of 5 longitudinal lines are required when using a large grid spacing on bridge decks. When a GPR survey has been previously carried out, the orientation of the grid lines should correspond to the orientation of the grid lines in the GPR survey. The spacing for the longitudinal grid lines is measured perpendicular to the longitudinal reference lines. However, when laying out transverse grid lines, measurements must be made parallel to the longitudinal reference line. The spacing for the vertical grid lines is measured perpendicular to the vertical reference line. However, when laying out horizontal grid lines, measurements must be made parallel to the vertical reference line. Grid lines are usually placed 0.1 m from the edge of the component except on bridge decks where they are normally placed 0.25 m to 0.5 m from the curb, barrier or expansion joint end dams. On bridge decks with longitudinal or transverse construction joints, a grid line should be placed 0.1 m from each side of the construction joint. Examples of grid layout are given in Appendix 1.B. Letter size grid sheets of the component should be prepared for data collection. Each grid sheet shall include the grid lines and cover a convenient portion of the component. Copies of the grid sheets are used in the field to record data collected on surface deterioration, asphalt depths, half cell potentials, concrete cover to reinforcement and soffit deterioration.

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It should be noted, that even if the grid layout is not required when no corrosion potential and concrete cover surveys are specified, grid sheets should still be prepared, so that defects may be plotted in their approximate location. 3.7.2 Post-Tensioned Decks with Circular Voids Based on past experience, half-cell readings are usually more negative directly over the voids than the adjacent areas. Hence, longitudinal grids for half-cell survey shall be located at every void and mid-point between them; additional grids to be at 0.25 m from curbs and then spaced at maximum 1.5 m until the first void. If the spacing of the voids is less than 1.5 m, spacing of the grids does not have to be less than 0.75 m, representative voids could be selected to reduce the total number of survey points. Transverse grids to be spaced at 1.5 m. Where a large asphalt strip is removed to expose the concrete surface, half-cell survey shall be conducted on the exposed surface using a grid of 0.5 m x 1.0 m with at least one grid line centred at the void; additional longitudinal grid lines shall be provided at cracks. 3.8 Equipment 3.8.1 General A list of equipment and tools required to carry out a detailed condition survey has been prepared to provide some guidance as to the type and variety of equipment required. Vehicles required to transport equipment and personnel and special access equipment, such as a boat, ladder or bucket truck, are not included. The equipment list is divided into three categories: general tools and materials; additional tools and materials for asphalt covered decks; tools and materials for anode resistance test. In some cases the sawing and coring is done by a subcontractor who specializes in that type of work. 3.8.2 General Tools and Materials These general tools and materials are required for all condition surveys. gasoline powered electric generator capable of providing power simultaneously to a core

drill, portable drill, and other equipment; extension cords; gasoline; electric core drill with 50 mm, 75 mm, 100 mm and 150 mm bits, core retrievers, water

tank and necessary hoses to supply water to core drill; wet/dry vacuum cleaner;

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a number of pieces of 13 mm plywood with wire attached suitable for using as forms when filling full depth core holes;

Ministry approved concrete repair material for filling core holes; shipping crates; canvas sample bags; four wheel dolly; pachometer (or Cover meter); voltmeter and suitable lead wire as specified in ASTM C876 (9); for decks with epoxy coated steel, AC ohmmeter capable of measuring 0.1 to 1000 ohms

and insensitive to AC and DC ground currents; for decks with epoxy coated steel, epoxy patching material, conforming to DSM

9.65.73(10), to repair damaged coating of epoxy coated bars; copper-copper sulphate half cell as specified in ASTM C876; portable electric drill with suitable 15 mm carbide bits; electric chipping hammer; thermometers for measuring air and concrete temperatures; sponges and rags; files; chisel; wire brush; screwdriver; vice grips; self tapping screws; rubber pails; nails; water; string and tape; camera, flash, telephoto lens and film; binoculars; flashlight; mirror on a pole; measuring tapes - 30 m and 5 m; measuring wheel; carpenter's level; plumb bob; crack comparator; prospectors pick-hammers heavy logging chain, typically 2 m long; blank forms; field books and scratch pads; field grid sheets; pens, pencils, pencil sharpeners and erasers; yellow marking crayons;

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personal safety equipment such as hard hats, safety shoes, safety vests, goggles, work gloves, safety belt, etc.;

traffic control items such as signs, delineators (cones) and flags. 3.8.3 Additional Tools and Materials for Asphalt Covered Deck The following additional tools and equipment are required for asphalt covered decks, in addition to those shown in Sections 3.8.2. Portable breaker/compactor and attachments; Gasoline powered saw, suitable for dry sawing asphalt complete with 400 mm blades; Spray can suitable for applying wetting solution; Caulking gun and Bituthene caulking material for filling holes drilled in asphalt for half

cell testing; Cold mix and Bituthene HDG waterproofing material for repairing core holes and sawn

sample areas. 3.8.4 Tools and Materials For Resistance Test The following additional tools and materials are required for measuring the resistance of anodes and probes on cathodically protected structures: cable locator; AC ohmmeter capable of measuring 0.1 to 1000 ohms and insensitive to AC and DC

ground current; nails (100 mm long); #10 AWG stranded copper cable; compression connectors; soldering kit; heat shrink tubing; propane torch; self-amalgamating tape. 3.9 Forms Standard forms required to carry out a detailed condition survey are described in Section 6.3 and are contained in Appendix 1.C.

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4. FIELD PROCEDURES Section 4 gives guidelines for procedures to be followed in the field and the amount of data to be collected in the field. 4.1 General The Consultants' Agreement will indicate whether a detailed visual inspection of the structure is required and will specify the extent of field data collection and sampling requirements for components that require a detailed condition survey. All data recorded in the field shall be complete, legible and unambiguous to avoid errors in preparing the final report and the drawings. 4.2 Detailed Visual Inspection The condition of structure components shall be visually assessed for material and performance defects as described in O.S.I.M. (4). The extent of the deterioration shall be estimated but not measured. No physical testing is required except that accessible areas shall be sounded in areas where delaminations are suspected. Colour photographs shall be taken of significant defects. Where a structure has been previously inspected according to O.S.I.M., the Ministry shall supply the consultant with the latest inspection data. The type and extent of deterioration shall be visually assessed and shall be compared to the previous conditions. Additional deterioration or repairs that have been made since the previous inspection shall be recorded, and the condition states of the components shall be adjusted accordingly. The changes in the O.S.I.M. inspection data will be entered by the Regional Structural Sections into the BMS database and updated reports will be produced. These shall be attached to the detailed deck condition survey reports. . 4.3 Detailed Condition Surveys 4.3.1 General The Consultant Agreement shall specify the data and sampling requirements for each component to be surveyed. All areas of deterioration, and data from half cell, cover and delamination surveys shall be recorded on field grid sheets in such a manner that the final drawings can be prepared. 4.3.2 Photographs Colour photographs are required and shall be taken with a digital camera. If at all possible, general views of the structure should be in a single photograph. Sawn sample photographs shall show the condition of the waterproofing membrane and the condition of the deck surface. For detailed deck condition surveys, a photograph is required of each expansion joint. Where extensive deterioration is evident, only typical areas need be photographed, e.g. a photograph of each spalled area is not required. Pictures of deteriorated asphalt over pancake anodes shall also be taken on cathodically protected bridge decks.

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Pictures should also be taken of the deck soffit inside the voids of thick concrete decks that do not contain post-tensioning cables and have no provision for access to inspect the inside of the voids. The picture can be obtained by inserting the camera through a full depth core hole. 4.3.3 Traffic Control Traffic control shall be implemented in accordance with the prescribed traffic control plan developed during the planning stage, see Section 3.5. 4.3.4 Grid Layout When the grid layout is required, the grid points shall be laid out as detailed on the letter size grid sheets described in Section 3.7. The grid layout may be modified if the reference lines chosen from the drawings are not acceptable. The marking of the grid points on the concrete surface is normally carried out by three persons. A crayon or keel shall be used in marking the grid points. For areas where it is difficult to layout a grid system, reference rulers can be demarcated on the component at the appropriate locations. The data collected should be plotted on the field drawings as accurately as possible using the reference rulers as reference. 4.3.5 Cathodically Protected Components Prior to the commencement of concrete coring and saw-cutting of asphalt, all embedded wires, anodes, probes and reference cells shall be located as per the layout given in the cathodic protection drawings. If possible, the location of cores and sawn samples shall be a minimum 2 metres from embedded wires or components; a cable locator should be used to confirm location of embedded wires if cores and sawn samples are to be taken within the 2 metre limit. Care shall be taken to avoid cutting the wires or damaging the cathodic protection hardware. Any damaged wiring shall be repaired. The system should be de-energized for at least four weeks prior to the commencement of the survey. 4.3.6 Equipment Calibration Standard forms are provided to document the data required for calibration of the equipment used for checking concrete cover and corrosion activity. A description of equipment used and the temperatures at the time of the test is also required. 4.3.7 Corrosion Potential Survey 4.3.7.1 Technique The corrosion potential survey is used to measure corrosion activity of reinforcing steel at the time of the test and is carried out in accordance with the requirements of ASTM C876-91 (9). Corrosion

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activity shall be measured by comparing the potential of the reinforcing steel with the potential of a standard reference cell. A copper-copper sulphate half-cell is used because it is rugged and stable. The numerical values obtained using a copper-copper sulphate half-cell are indicative of conditions as listed below. If potentials over an area are numerically less than -0.20 V, there is a greater than 90%

probability that no reinforcing steel corrosion is occurring in that area at the time of measurement.

If the potentials over an area are in the range -0.20 V to -0.35 V, corrosion activity of the

reinforcing steel in that area is uncertain. If potentials over an area are numerically greater than -0.35 V, there is a greater than 90%

probability that reinforcing steel corrosion is occurring in that area at the time of measurement.

4.3.7.2 Procedure for Concrete with Uncoated Reinforcing Steel The multimeter battery shall be checked at the start of the test. The location and concrete cover to the ground, the method of connecting to ground, the total resistance and voltage drop measured for electrical continuity check, and the resistance of lead wire shall be recorded. At least five potential measurements shall be checked at the beginning and the end of the test, and each time a new ground is used. Duplicate readings should differ by no more than 0.02 V. Where greater differences are recorded the test shall be repeated. Since corrosion activity is a function of temperature, readings shall not be taken when the air and concrete temperature is lower than 5o C. The concrete temperature shall be measured in a shaded area of the structure. For the results to be accurate, the concrete should have sufficient moisture to be conductive but should have no standing water at the time of the corrosion potential survey. Pre-wetting of the grid points is recommended for surveys carried out during prolonged dry spells. On exposed concrete decks the presence of contaminants may influence the readings obtained. Therefore, the concrete surface shall be removed to a 2 mm depth at each grid point using chipping hammers or by grinding. A positive ground connection shall be made directly to the reinforcing steel. The ground connection should be made with a self-tapping screw or compression clamp. When a compression clamp is used, all corrosive deposits should be removed at rebar ground location. The use of adhesive tape for grounding the reinforcing steel is not acceptable. A separate ground shall be used for each portion of the component that is not continuous. The reinforcing steel should be checked for electrical continuity by measuring the resistance (ohms) and voltage drop (mV's) between the ground and another rebar which is far as possible and

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diagonally opposite from the ground connection. The resistance should be measured one way and then the polarity of the leads should be reversed and the resistance measurements should be repeated. When the above procedure is followed, discontinuity of the reinforcing steel will be indicated by any one of the following: any resistance reading more than 5 ohms or a negative number (after deducting the

resistance of the test leads); resistance readings that are unstable; voltage drop readings greater than 3.0 mV's. If electrical continuity cannot be established on the first attempt, the ground connection should be checked. If ground connection is secure and resistance and voltage drop is still high, the continuity check shall be repeated using different rebars for ground connection and/or resistance check. The survey should be subdivided into smaller areas on long bridge decks. In some older decks with black smooth round bars, it is not possible to carry out a half-cell survey as there is no continuity between the bars. Corrosion potential readings shall only be taken in the core and sawn sample locations on structures that are protected with the conductive asphalt CP system. Care shall be taken to avoid contact between the half-cell and the conductive asphalt when potential readings are made. Corrosion potential readings are required at all grid points on structures that are not cathodically protected. A 15 mm diameter hole shall be drilled through the asphalt and any waterproofing material to make contact with the concrete. The drilling dust shall be removed from the holes by vacuum or air blasting before adding the wetting solution to take the reading. Asphalt depths shall be measured in the holes drilled for corrosion potential tests. It is recognised that an exact measurement is not possible because of the difficulty in defining when contact is made between the drill bit and the deck surface. However, small errors are not significant in relation to the large number of readings taken. On decks with a latex modified concrete overlay treatment, an additional set of corrosion potential readings should be obtained at 5 grid point locations via 15 mm diameter holes that have been drilled through the latex modified overlay into the original concrete substrate to verify that the readings are the same as those taken at the top of the overlay. All drill holes shall be repaired by removing the wetting solution and caulking with bituthene caulking material for the full depth of the hole. Fine sand shall be sprinkled on the surface to prevent tracking. 4.3.7.3 Procedure for Concrete with Epoxy Coated Reinforcing Steel A regular type of half-cell survey cannot be carried out on decks with epoxy coated reinforcing steel as there is no electrical continuity between the different coated reinforcing bars. However,

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the condition of the reinforcing steel can be assessed by taking localised corrosion potential readings and measuring AC resistance and voltage (IR) drop between reinforcing steel at locations where rebars are exposed as part of the concrete coring operation. Only reinforcing steel in the top layer of the top mat should be tested. The AC resistance and IR drop testing should be carried out at 5 widely separated core locations where reinforcing steel is exposed. As failure of the epoxy coating is more likely along curbs and barrier walls, it is recommended that 3 of the readings be obtained in these locations. The connections to reinforcing steel shall be made with a self-tapping screw at each test location. An AC resistance and IR drop measurement shall be made between each pair of test points covering all possible combinations. When taking the IR drop measurement, it is important that the polarity of the connection and the sign of the reading be recorded. As the AC resistance measurement is actually the sum of the AC resistance of two rebars and the concrete, the AC resistance contributed by the individual bars will have to be calculated using the procedure in Appendix 1.E. Generally, a low AC resistance reading probably indicates that epoxy coating has failed to protect the steel from corrosion. However, as AC resistance is not only related to condition of coating but also to size and length of the reinforcement, the criteria for assessing the condition of coated reinforcing steel based on AC resistance cannot be finalised until more data is collected. Half-cell readings shall be taken at all locations where reinforcing steel is exposed by the coring operation. The connection to the rebar and location of the half- cell should be at the same rebar. A smaller type half-cell can be used for taking readings inside the core hole. The reading can be very unreliable when the half-cell location does not correspond to the same rebar as the ground connection. All data, both measured and calculated, shall be recorded on the Epoxy Coated Reinforcing Steel Summary Sheet and the Detailed Condition Survey Summary Sheet in Appendix 1.C. 4.3.8 Concrete Cover Survey 4.3.8.1 Technique The concrete cover over the outer layer of reinforcing steel shall be measured using an approved cover-meter. The cover-meter measures the disturbance in a magnetic field and the magnitude of the disturbance is proportional to the size of the bar and its distance from the probe. The cover to the top bar in the top mat shall be measured nearest the grid point or by taking an average of the bars on either side of the grid point. The existing structure drawings shall be checked to determine orientation and the size of top bars (note if bar size is constant). The cover-meter shall be operated with the probe oriented parallel to the top bars. If the structure drawings are not available and the orientation of the top bars is not known, the probe shall be rotated at several locations until a sharply defined minimum reading

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(maximum deflection) is obtained. This indicates the probe is directly above a bar, and the orientation of the bar coincides with the longitudinal axis of the probe. 4.3.8.2 Procedure A battery check shall be made at the start and end of the test. On some instruments the calibration tends to drift while in use. Therefore, the instrument shall be calibrated at a core hole where a bar location is known or at an exposed bar, and checked periodically (as per Equipment Calibration Form). This procedure will also identify if there are magnetic particles in the concrete for which a correction factor must be derived. On decks with exposed concrete surfaces, the cover shall be measured on a 3 m x 3 m grid. On decks with an asphalt surface, the cover shall be measured in areas where sawn samples have been removed. On other concrete surfaces the cover shall be measured at a maximum 1m x 1 m grid for components less than 50 m2 and on a 2m x 2m grid if the area of the component is greater than 50 m2. The value recorded shall be the cover to the uppermost bar nearest to the intersection of the grid lines. Reinforcing steel is tied together to form a relatively rigid mat. As a result, any significant change in the cover readings at adjacent points should be viewed with suspicion and additional readings taken to confirm the results. 4.3.9 Delamination Survey 4.3.9.1 Technique Delaminations in concrete are detected by striking the surface and noting the change in sound being emitted. Several methods, using tools such as hammers, steel rods, chains and, more recently, electronic acoustical devices, radar and thermography, have been used for detecting delaminations in concrete. The chain drag method has been found to be the most suitable for detecting delaminations on the top surface of bridge decks. The chain is moved from side to side in a swinging motion along the surface of the concrete. A change in the normal ringing sound to that of a dull sound would normally indicate that a delaminated area has been encountered. A heavy chain (2.2 kg/m with 50 mm links) has proved to be most suitable, especially, in areas where there is interference from traffic noise. The chain drag is, generally, used in detecting delaminations on exposed horizontal concrete surfaces only. It can be useful, though, as a quick method of identifying potentially debonded areas in asphalt covered decks, that might require further investigation. However, these areas are not measured and recorded.

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Hammers and steel rods are used to detect delaminations on vertical and overhead surfaces. If the striking object is highly resonant, the difference between sound and delaminated concrete may be difficult to distinguish. Therefore, care must be taken when interpreting the sound produced. 4.3.9.2 Procedure Delaminated areas shall be marked directly on the surface of the components using a red crayon. The areas are then measured (size and location) and recorded on the appropriate grid sheet. 4.3.10 Concrete Surface Deterioration Survey The area and location of patches, spalls, exposed reinforcement, honey-combing, wet areas, scaling and other observed defects and deterioration shall be recorded on the field grid sheets. See OSIM, Part 1, Section 2, for description of defects commonly occurring in concrete. The severity of scaling shall be visually assessed and classified according to the categories given in Table 4.1.

Severity of Scaling

Depth, mm

light

0 to 5

medium

6 to 10

severe

10 to 20

very severe

over 20

Table 4.1 / Classification of Scaling

The width of cracks shall be measured using a crack comparator. The size and location of cracks shall be recorded with respect to the grid lines. On exposed surfaces the cracks are classified according to the scale given in Table 4.2 and the letter M or W is noted beside each crack on the grid sheet. Cracks that are leached or stained shall be labelled separately. For condition survey purposes the location and length of cracks narrower than 0.3 mm (shrinkage cracks) need not be recorded for most components; however, shrinkage cracks or pattern cracks shall be noted under the remarks column of the detailed condition survey summary sheet. Cracks wider than 0.25 mm should be recorded for concrete beams and girders.

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If measuring depth of the medium and wide cracks is specified in the consultant's agreement, the depth shall be measured using feeler gauges or fine wires. The crack surfaces should also be carefully assessed for degree of contamination and leakage.

Severity of Cracking

Crack Width, mm

Medium (M)

0.3 to 1.0

Wide (W)

> 1.0

Table 4.2 / Classification of Cracking In the case of detailed condition surveys for decks, concrete surface deterioration of the deck soffit shall be recorded on a separate grid sheet on the same grid layout as the deck surface. The location of any void drains shall be noted. When a delamination survey is required for the deck soffit the areas of deterioration shall also be measured. On asphalt covered decks, the general condition of the asphalt and cracks wider than 3 mm shall be recorded. Sealed cracks shall also be recorded. Any defects in the surfacing which may be indicative of deterioration in the concrete deck slab shall be recorded. On decks with the conductive bituminous overlay system of cathodic protection, the condition of asphalt over the pancake anodes should be noted. 4.3.11 Expansion Joint Survey - Bridge Decks The expansion joints shall be visually assessed for material and performance defects as described in O.S.I.M. (4) and the type and extent of the deterioration shall be recorded on the Detailed Condition Survey Summary Sheet for expansion joints. Although no physical testing is required, measurements to determine the joint dimensions shall be taken and recorded on the summary sheet. The dimensions of each joint are required even where there is no armour or seal because new joints are usually installed as part of the rehabilitation contract. All joint gaps should be measured perpendicular to the line of the joint. Where the joint has been paved over, the asphalt must be removed at the curbs and at the centreline of the highway in order to measure the joint gap. There may be exceptional circumstances, such as the use of sliding plates where it is not possible to measure the joint gap. However, the engineer should be aware of this situation from the review of the plans and should make a note on the form in the section for remarks.

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The deck temperature shall be taken 50 mm below the surface on exposed concrete decks and at the asphalt-concrete interface on asphalt-covered decks. The ambient temperature shall be the shade temperature, usually taken below the structure. Sketches of typical sections of the expansion joint in the curb or sidewalk area as well as the driving lane area are required. The sections shall show any steel angles, steel cover plates, dimensions of concrete end dams and other pertinent information. The width of the top of the ballast wall shall be measured. If the ballast wall is paved over, the asphalt must be removed at one location for each abutment in order to measure this width. The thickness of asphalt at the concrete end dams shall be measured at the curbs and at the centreline of highway on the bridge deck. Asphalt shall be removed by coring or other suitable methods. The quality of concrete in the deck, curbs and ballast walls adjacent to the joint shall be noted under remarks. 4.3.12 Drainage - Bridge Decks Deck drains shall be visually assessed for material and performance condition defects as described in OSIM and the type and extent of deterioration shall be recorded on the Detailed Condition Survey Summary Sheet for drainage. Although the deck drainage portion of the summary sheet is self-explanatory, additional instructions are given below: a. The size of the drains shall be measured. The length and angle of inclination of the drains

may be estimated. b. The boxes given for recording the location of catch basins is suitable for most structures.

A separate sketch will be required for unusual alignments or complex geometry. The deck soffit should be inspected for the presence of void drains on voided decks and asphalt drainage tubes on decks with transverse expansion joints. 4.3.13 Concrete Cores 4.3.13.1 General A covermeter shall be used to avoid coring through the top mat of steel. However, in areas of high corrosion potential with sound concrete some cores should be taken through the steel to observe the condition of the rebar. Cores shall not be taken through pre-stressing steel, utility ducts, embedded cathodic protection components (including cables) or in areas immediately below or

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above the bearings. The cores shall be long enough to carry out the required tests and shall extend below the top mat of reinforcing steel. Where the concrete being cored is in poor condition and is broken into several fragments, the juxtaposition of the pieces shall be recorded, by either a sketch or identification of individual pieces, so that the core can be pieced together in the laboratory. Cracks in the concrete core caused by the coring operation should be identified as such. The inside of the core hole shall be examined carefully for horizontal cracks and the condition of the concrete. The condition and orientation of any rebar located in the side of the hole shall also be recorded. Each core shall be given a number that identifies the structure and its location in the structure. The location and the number (prefaced with 'C') of the cores shall be noted directly on the grid sheets and the core logs. It is a good practice to complete the dimensions and remarks section of the core log forms in the field, since this reduces the possibility of errors in identifying cores. The location of the cores shall be given with respect to the grid lines. 4.3.13.2 Bridge Deck Riding Surface The number of cores required is specified in Table 4.3. Some cores may be taken before the completion of non-destructive testing. When this is done the coring operation shall be contained and any excess water shall be vacuumed frequently. Care shall be taken to prevent water from the coring operation interfering with the corrosion potential measurements and sawn sample operation. Cores shall be taken in areas where deterioration is suspected; i.e. near curbs, in areas of poor drainage, at cracks or wet spots in the soffit, in areas of high corrosion potential, in areas of delaminations identified by GPR survey (if available), and at cracks in the asphalt surface. However, it is also intended that the cores be representative of the condition of the concrete. Consequently, a sufficient number of cores shall also be taken from areas with lower corrosion potential (between 0.0 to 0.35 volts) to determine the extent of delaminated concrete in this area. Sound cores will, in any event, be required for physical testing. At least one core, free from reinforcing steel, shall be used for compression testing. At least two cores shall be taken from each span and where the structure has been widened, a sufficient number of cores shall be taken from old and newer portions of structures to carry out the physical testing. One of the cores shall be taken the full depth of a thin deck slab. At least 3 cores shall be taken full depth through the top slab of thick voided concrete slabs that are not post-tensioned and do not have provisions for access to inspect the inside of the voids. The cores should be taken in the areas of suspected deterioration for the purpose of photographing the underside of the slab. For post-tensioned decks with circular voids, all cores shall be taken at solid web areas between voids where the cables are sufficiently deep to avoid being damaged by coring. Furthermore, at least one core shall be taken at a longitudinal crack within the large asphalt strip removal area, just

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deep enough to exposed the condition of the top reinforcement. If there is delamination of an existing overlay within the large asphalt strip based on sounding, then a core should be taken at the delaminated area to see if the overlay has debonded. On decks with uncoated reinforcing steel, the total number of cores required will not be known until the corrosion potential survey is completed. The additional cores required shall be concentrated in the areas that according to the GPR survey are delaminated or in areas with corrosion potentials more negative than -0.35 volts. On decks with epoxy coated reinforcing steel, the total number of cores shall be the minimum specified in Table 4.3 plus additional cores in delaminated areas identified by the GPR survey. For the AC resistance measurements, 5 cores are required directly over a reinforcing bar at 5 widely separated locations; they should consist of 3 cores along the curb/barrier wall and 2 cores towards the centre line of the deck. If necessary, these cores can be tak