Lecture 01 - Introduction

Transcription

1 Rak-4. Repair Methods of Structures II Lecture 0 - Introduction Mon Lecture outlines Introduction of the course (Course syllabus) Course information Learning outcomes Evaluation and grading Course assignment (Building facades - repair plan)

2 Course content Condition assessment Repair principles Deterioration mechanisms Recommended repair methods Preparation for repair Repair of moisture problems Repair and protection of Reinforcing steel Repair of facade structures Repair of service systems Remaining service life evaluation Rak-4.0 Repair Methods of Structures I Rak-4. Repair Methods of Structures II Course information Instructors contact information Names: Esko Sistonen and Fahim Al-Neshawy firstname.surname@aalto.fi Office: Esko: (Room R68b) Fahim: (Room R7) Instructors Webpage: Course information Status of the course: Master degree course Academic Year, Period: Spring 06 (Period III) Location: Otaniemi / Lecture hall R5 Language of Instruction: English Course Website: hp?id=846 4

3 Course learning outcomes. Explain the regulations and guidelines for repairing. Classify suitable repairing methods for building structures. Identify the service life of building structures 4. Examine the repairing methods and the service life of building structures 5 Evaluation and grading Course: Rak-4. Repair Methods of Structures II Teaching methods Lectures & literatures Excursions (CBL) Group work (PBL) Evaluation method Examination Excursion report Assignment, peer reports and presentation Grading method (0 5) 50% of the total grading Pass / Fail CBL = Case Based Learning PBL = Problem Based Learning (0 5) 50% of the total grading 6

4 Course assignment (Building facades - repair plan) Repair plan: (plan created by the assignment group) The nature of the defect to be corrected, A detailed procedure for making the repairs A plan outlining the repair phases and a time schedule for the repairs. Estimation of the remaining service life (life extension of proposed repair methods) 7 This lecture Repair terminology EN The phases of a typical repair projects 8

5 Suggested readings for this lecture WEBER, Saint-Gobain Construction Products UK - Common problems faced by construction specifiers: Available online at: M. Raupach, Concrete Repair According to the new European Standard EN 504 Available online at: /technical-mortarssolutions/help-andadvice/problemsolutions.html pload/forschung/docs/8484 _Raupach.pdf 9 Repair terminology Refurbishment of buildings: involve giving outdated buildings a new purpose with an upgrading and reconfiguration that goes beyond the cosmetic. Rehabilitation: the process of repairing or modifying a structure to a desired useful condition. Refurbishment Rehabilitation 0

6 Repair terminology Restoration: The process of re-establishing the materials, form, and appearance of a structure to those of a particular era of the structure. Retrofitting: refers to the addition of new technology or features to older systems. For example home energy retrofit, the improving of existing buildings with energy efficiency equipment Restoration Retrofitting Repair terminology Full-depth repair : removal and replacement of damaged or deteriorated concrete that constitutes the full depth of a member or element. Partial-depth repair: removal and replacement of damaged or deteriorated near-surface concrete that constitutes only a portion of the depth of a member or element. Full-depth repair Partial-depth repair

7 Repair terminology Structural repair: is a repair that restores or enhances the structural capacity of a member. Structural repair Nonstructural repair: protective repair that is not intended to affect the structural capacity of a member. Non-Structural repair Concrete repairs - Standards The European Standard EN 504 Products and systems for the repair and protection of concrete structures - definitions, requirements, quality control and evaluation of conformity 4

8 European Standard EN 504 The 0 documents forming the EN 504 Series are listed below: Part Content Definitions Surface protection systems Structural and non structural repair 4 Structural bonding 5 Concrete injection 6 Products and systems for grouting anchor reinforcement 7 Reinforcement corrosion protection 8 Quality control and evaluation of conformity 9 General principles for use of products and system 0 Site application of products and systems and quality control of the works 5 EN The phases of a typical repair projects Defects and their classification and causes Options, Principles and Methods Acceptance testing Choice of products and equipment quality control Health and safety Intended use of products Requirements Specifications and drawings Safety 6

9 EN The phases of a typical repair projects 7 EN The phases of a typical repair projects Step- Documentation of damage.(type & extent) Step- Preparation of drawings, sketches, execution guidelines, material specifications modalities of payment etc.. Step- Actual Execution with understanding, proper expertise, resources for effectiveness of repairs. 8

10 EN The phases of a typical repair projects Rational approach to any repairs works. Identification of cause of deterioration Consequent repairs and rehabilitation strategy Scientific evaluation and solution for protection-repairs, rehabilitation, strengthening and retrofitting taking advancement in material science. 9 EN The phases of a typical repair projects 0

11 EN The phases of a typical repair projects EN The phases of a typical repair projects

12 Classification of repairs Class : No distress but cosmetic repairs Class : Minor repairs: superficial (pinnallinen) repairs Class : Medium repairs (patch repairs) Class 4 : Medium, but principal repairs Class 5 : Major repairs Selection of repair material for concrete Selection criteria: Allow minimum movement Minimal or no curing requirement Alkaline character Low air and water permeability Aesthetics with surroundings Durable / non degradable / UV resistant Cost effectiveness Non hazardous / non pollutant. 4

13 Selection of repair material for concrete Selection criteria: Low shrinkage -> less crack/ access to air / water Minimum time to harden and make available space Workability Ease of application Bond with substrate -> strength and structural behavior criteria Compatible coefficient of thermal expansion Mechanical properties / E s (elastic modulus) Appearance 5 Materials for repairs Materials for surface preparation Chemical rust removers for reinforcement Passivators for protection of reinforcement Bonding agents Structural repair material Non-structural repair material Injection grout Joint sealers Surface coatings for protection of RCC 6

14 Materials for repairs: examples Polymer modified mortar is used on hardened concrete surface for repairing defects Epoxy mortar : (Resin + hardener +silica sand) Attains strength in short time and is abrasion resistant and is used when it is difficult to use epoxy bonded concrete, depth of repairs is less than 40mm etc. Shotcrete : Pneumatically applied concrete or mortar may be with fibers of steel, poly propylene with admixtures to enhance structural properties 7 Repair options Grouting and crack repairs Patch repair Replacement of structurally weak concrete Replacement of delaminated concrete Replacement of corroded steel reinforcement Cleaning and passivating reinforcement Concrete and corrosion protection ( Jacketing) 8

15 Factors in selection of methods of repairs Type and extent of repairs Location of distress Environmental exposure Availability of skill Availability of time and access for repairs Appearance Cost 9 Review Concrete repair principles and methods 0

16 Principle Protection against ingress BS EN 504-9:006 BS EN 504 Principle is protection against ingress by reducing or preventing the ingress of adverse agents, e.g water, other liquids, vapour, gas, chemicals and biological agents. Protection against ingress includes measures to reduce the porosity or permeability of the concrete surface by treatment using surface protection systems to BS EN 504- or sealing cracks by injection or filling to BS EN a Water ingress Carbonation Carbon dioxide in the atmosphere can cause carbonation. CO CO Cracked and delaminated concrete This can be the first sign that there is a corrosion problem and left untreated can cause further problems. These defects should be repaired using Repair Principles, BS EN 504. See pages Moisture ingress Moisture ingress due to rising damp and contact with ground 5 Water ingress ponding Saturated concrete due to water ponding can lead to freeze-thaw damage to exposed concrete slabs or pavement. This leads to delamination of the concrete surface. De-icing salts can cause chloride-induced corrosion. 8 Non-structural cracks appearing in the surface of the concrete can allow water to penetrate and set up corrosion of the rebar reinforcement. Water ingress through rainfall in areas of high rainfall or severe exposure. b Non-structural cracks

17 Solution Principle : Protection against ingress BS EN 504-: Surface protection systems for concrete BS EN 504-5: Concrete injection Methods of protection based upon the BS EN 504 Principle is the use of the following: a. Surface impregnation.. Surface coating with and without crack bridging capability.. Locally bandaged cracks. Surface impregnation Low-viscosity penetrating surface sealer weber.tec acrylic sealer.4 Transferring cracks into joints..5 Erecting external panels..6 Applying membranes. Transferring cracks into joints: non-structural crack sealer Low-viscosity acrylic co-polymer crack sealer weber.tec mulsibond BS EN 504- BS EN a b Surface coating Anti-carbonation coatings weber.cote smooth weber.cote clear weber.cote EC santane EFL BS EN 504- Erecting external panels: concrete repair and EWI weber.cem HB0 and weber.therm XP BS EN 504- see Weber Render Solutions handbook 4 Applying membranes: waterproof membrane Cement-based waterproof render or waterproof coating weber.cem dryrend 5 weber.cem drycoat 5 BS EN Surface impregnation Acrylic resin in-surface sealer weber.tec acrylic sealer Areas of use BS EN 504- Buildings Bridges Piers, jetties etc Car parks and more... For detailed instructions, please refer to the relevant product data sheet. For further information, please contact our Technical Helpline on

18 Principle Moisture control BS EN 504-9:006 BS EN 504 Principle is concerned with moisture control by adjusting and maintaining the moisture content in the concrete within a specified range of values. Moisture control is used to control adverse reactions (such as alkali-silica reaction or sulphate attack) by Moisture control Water ingress through rainfall in areas of high rainfall or severe exposure. MC Water penetration into concrete Concrete subject to water penetration can induce reinforcement corrosion. MC Moisture ingress Moisture ingress due to rising damp and contact with ground MC 40 allowing concrete to dry as well as preventing moisture build-up.

19 Solution Principle : Moisture control BS EN 504-: Surface protection systems for concrete Methods of protection based upon the BS EN 504 Principle is the use of the following: a...4 Hydrophobic impregnation. Surface coating. Sheltering and overcladding. Electrochemical treatment. Surface coatings Anti-carbonation coatings weber.cote smooth weber.cote clear weber.cote EC santane EFL MC BS EN 504- b Hydrophobic impregnation MC Silane-based water repellent weber.tec aquapel WR BS EN 504- Sheltering and overcladding Use of external wall insulation, EWI, to control moisture. weber.therm XP see Weber Render Solutions handbook MC Hydrophobic impregnation Silane-based in-surface water repellent weber.tec aquapel WR MC Areas of use BS EN 504- Buildings Bridges Piers, jetties etc Car parks and more... For detailed instructions, please refer to the relevant product data sheet. For further information, please contact our Technical Helpline on

20 Principle Concrete restoration BS EN 504-9:006 BS EN 504 Principle is concerned with concrete restoration by restoring the original concrete element of the structure to the originally specified shape and function. Concrete restoration is normally carried out using hand-applied patch repairs, recasting with concrete or applying concrete or mortar by spraying. The scope of BS EN 504- includes materials suitable for structural and non-structural repairs. 5 Spalled concrete Reinforcement corrosion Reinforcement corrosion due to carbonation, low concrete cover and high w/c ratio, leading to spalled concrete and loss of section to reinforced concrete element. From broken concrete to exposed areas of concrete, due to cracking, reinforcement corrosion or chemical attack. Spalled concrete to soffits Broken concrete due to reinforcement corrosion or fire damaged concrete. Delaminated concrete Hollow or delaminated concrete due to reinforcement corosion to surface steel rebar. 4 Physical damage Freeze-thaw damage to pavement-quality concrete or impact damage. 6 Impact damage Damaged concrete due to vehicle collision or mechanical damage leaving exposed steel rebar and loss of section 4

21 Solution Principle : Concrete restoration BS EN 504-: Structural and non-structural repair Methods of protection based upon the BS EN 504 Principle is the use of the following:....4 Applying mortar by hand. Recasting concrete. Sprayed concrete. Replacing elements. Hand-applied mortar 5 Table Class Nonstructural R R Structural Strength Product > 0 MPa > 5 MPa weber.cem lightweight R > 5 MPa weber.cem HB0, weber.cem HB40 R4 > 45 MPa weber.cem mortar, weber.tec EP highbuild Recasting concrete Using a structural, selfcompacting, non-shrink micro concrete. Five Star repair concrete Five Star repair concrete CP Method. Hand-applied mortar to non-structural and structural repair. Method. Sprayed concrete To restore section of damaged concrete without the use of formwork and for rapid reinstatement to walls and soffits. weber.cem spray DS weber.cem spray RS weber.cem spray DSF weber.cem spray CP weber.cem conspray Method. 4 Recasting concrete to pavement Using fast-setting repair concrete for permanent quality. weber.cem pyrapatch weber.cem pyratop Method. 6 Hand-applied mortar Using lightweight epoxy mortar for Class R4 structural repair. weber.tec EP highbuild weber.cem mortar Areas of use Method. Buildings Bridges Piers, jetties etc Car parks and more... For detailed instructions, please refer to the relevant product data sheet. For further information, please contact our Technical Helpline on

22 Principle 4 Structural strengthening BS EN 504-9:006 BS EN 504 Principle 4 is concerned with structural strengthening by increasing or restoring the structural load bearing capacity of an element of the concrete structure. It is essential when using this Principle that all stresses associated with a repair and the original or deteriorated structure are considered. Certain systems may impose additional stresses on the repaired structure, resulting in changes in the function of the original structure. 5 Overloading Overloading to structural elements due to extra loads applied to columns, forming structural cracks to columns and beams. SS Deflections Deflections due to increases in loads applied to the original structure, forming cracks to reinforced concrete slabs. SS Voids or insufficient reinforcement Voids in the concrete or insufficient rebar found in the structure. SS Seismic damage Damage due to earthquakes or sudden impact (explosions), causing structural failure and cracking. SS 4 Structural bonding Hardened precast concrete to hardened precast concrete for repair. SS 6 Cracking Cracking to structural concrete due to insufficient reinforcement, flexural cracks, shear loading or overloading. SS 44

23 Solution 4 Principle 4: Structural strengthening BS EN 504-: Structural and non-structural repair BS EN 504-4: Structural bonding BS EN 504-5: Concrete injection Methods of protection based upon the BS EN 504 Principle 4 is the use of the following: 4. Adding or replacing emedded or external reinforcing steel bars. 4. Installing bonded rebars. 4. Plate bonding. Plate bonding to floor slabs 5 Using FRP carbon-fibre plates bonded as external reinforcement to strengthen reinforced concrete. Bonded FRP to tension face. weber.tec force carbon plate S&P 50 kn/mm² modulus S&P 00 kn/m²modulus SS Adding mortar or concrete. Injecting cracks or voids. Filling cracks or voids. Prestressing. Strengthening columns Using near surface mounted, NSM, reinforcement and sheet wrap weber.tec force carbon plate 0 mm 0 mm weber.tec force carbon sheet weber.tec force aramid sheet SS BS EN BS EN a Filling cracks or voids: crack injection Using epoxy resin. weber.tec EP IK weber.tec EP injection resin SS BS EN b Filling voids Use cement grout for filler joists and grouting anchor rebar. weber.cem duct grout weber.tec anchor grout Use FRP sheet wrap and FRP plates. weber.tec force carbon plate weber.tec force aramid sheet weber.tec force glass sheet weber.tec force carbon sheet BS EN Structural bonding Using epoxy structural adhesive. weber.tec EP structural adhesive SS 6a Strengthening to walls SS 4 BS EN Shear strengthening Using ultra-high modulus, UHM, carbon-fibre sheet. weber.tec force carbon sheet, C640 SS Areas of use BS EN b Filling cracks Epoxy resin crack injection weber.tec EP IK SS BS EN Buildings Bridges Piers, jetties etc Car parks and more... For detailed instructions, please refer to the relevant product data sheet. For further information, please contact our Technical Helpline on

24 Principle 5 Increasing physical resistance BS EN 504-9:006 BS EN 504 Principle 5 is concerned with increasing physical resistance of the concrete to physical or mechanical attack. Removal of the concrete surface by physical actions such as impact or abrasion may affect the performance of the structure. The causes need to be identified and physical protective measures may need to be taken to reduce their effects as well as applying the repair methods. Fire damage Fire damage to reinforced concrete walls, columns and soffits. PR Abrasion Abrasion to floor slabs and pavement-quality concrete, resulting in loss of surface and loss of skid resistance. PR Impact damage Impact damage to floor slabs and pavementquality concrete. PR 4 Impact damage Impact damage to structural reinforced concrete elements. PR 46

25 Solution 5 Principle 5: Increasing physical resistance BS EN 504-: Surface protection systems BS EN 504-: Structural and non-structural repair BS EN 504-4: Structural bonding Methods of protection based upon the BS EN 504 Principle 5 is the use of the following: To restore section of damaged concrete without the use of formwork and for rapid reinstatement to walls and soffits. weber.cem spray DS weber.cem spray RS weber.cem spray DSF weber.cem conspray Coating Coating applied to concrete floor and walls to improve abrasion resistance and non-slip. weber.tec EP coating weber.tec EP coating WD weber.tec PU sealcoat BS EN 504- BS EN 504- In-surface impregnation Impregnation of the concrete surface to harden the concrete with an an acrylic resin in-surface sealer. weber.tec acrylic sealer Overlay sprayed concrete 5. Overlays or coatings. 5. Impregnation. BS EN 504- Recasting concrete Recasting concrete to pavements and floor slabs and joint arris. weber.cem pyratop weber.cem pyrapatch weber.tec EP mortar weber.tec EP highbuild BS EN 504-4a Hand-applied mortar To structural elements using cementbased or epoxy-based mortar. weber.cem HB40 weber.tec EP highbuild Areas of use 4b Structural wrap Structural wrap to columns to prevent impact damage. weber.tec force aramid sheet BS EN 504- SS BS EN Buildings Bridges Piers, jetties etc Car parks and more... For detailed instructions, please refer to the relevant product data sheet. For further information, please contact our Technical Helpline on

26 Principle 6 Resistance to chemicals BS EN 504-9:006 BS EN 504 Principle 6 is concerned with increasing the resistance of the concrete surface to wear, erosion and impact damage. Where concrete has been attacked by chemicals the nature of the attack and the chemicals need to be identified and protective measures taken to reduce their effects and apply the repair methods. Soils, water treatment works and sewage can generate acids or sulphates that can promote attack on the concrete and reinforcement. Aggressive environments Such as sewage treatment works and chemical storage areas can lead to breakdown of concrete. RC Chemical attack Chemical attack to the surface of the concrete due to accidental spillage or aggressive environment. RC Sulphate attack Sulphate attack due to soil and backfill coming into contact with reinforced concrete, leading to concrete spalling. RC 48

27 Principle 6: Resistance to chemicals BS EN 504-: Surface protection systems for concrete BS EN 504-: Structural and non-structural repair Solution 6 Methods of protection based upon the BS EN 504 Principle 6 is the use of the following: 6. Overlays or coatings. 6. Impregnation. Aggressive environments The solution depends on the nature of the aggressive environment. For certain marine situations e.g. piers and jetties in new structures or where salts have been removed, impregnation with a pore lining water repellent treatment may help to reduce the ingress of salts. BS EN 504- a In-surface impregnation Impregnation of the concrete surface to harden the concrete with an an acrylic resin in-surface sealer. weber.tec acrylic sealer BS EN 504- b Coating Coating applied to the concrete floor or wall to provide chemical resistance. weber.tec EP coating weber.tec EP coating HB weber.tec PU sealcoat BS EN 504- Overlay Overlay with sulphate resistant mortar to protect reinforced concrete. weber.cem dryrend 5 weber.tec EP highbuild BS EN 504- Areas of use Buildings Bridges Piers, jetties etc Car parks and more... For detailed instructions, please refer to the relevant product data sheet. For further information, please contact our Technical Helpline on

28 Principle 7 Preserving or restoring passivity BS EN 504-9:006 BS EN 504 Principle 7 is concerned with preserving or restoring the passivity of the concrete by creating chemical conditions in which the surface of the reinforcement is maintained in or is returned to a passive condition. Where the reinforcement is passive, an additional layer of mortar or concrete may be added over carbonated concrete to provide additional protection. 4 Carbonation Delaminated concrete Due to widespread carbonation or chlordeinduced corrosion. RP Permeable concrete Permeable concrete due to inadequate curing, shrinkage cracks, poor compaction and a weak surface layer to the concrete. RP 50 Low concrete cover to reincorcement in exposed areas of the structure. RP Carbonation to concrete leading to reinforcement corrosion and localised spalled concrete to areas of low concrete cover. RP Low concrete cover

29 Solution 7 Principle 7: Preserving or restoring passivity BS EN 504-: Structural and non-structural repair Methods of protection based upon the BS EN 504 Principle 7 is the use of the following: Increasing concrete cover to reinforcement. Replacing contaminated or carbonated concrete. Electrochemical realkalisation of Replacing concrete Replacing concrete with hand-applied mortars and a corrosion inhibitor. weber.cem HB0 weber.cem HB0 weber.tec guard MCI carbonated concrete. Re-alkalisation of carbonated concrete by diffusion. Electrochemical chloride extraction. Increasing concrete cover Increasing cover with additional mortar or concrete. weber.cem fairing coat weber.cem spray DS BS EN 504- BS EN 504- Sprayed concrete To replace contaminated concrete and to increase concrete cover. weber.cem spray DS weber.cem spray RS weber.cem spray DSF weber.cem conspray BS EN 504- Recasting concrete Recasting concrete to pavement to improve and restore passivity. weber.cem pyrapatch weber.cem pyratop Areas of use BS EN 504- Buildings Bridges Piers, jetties etc Car parks and more... For detailed instructions, please refer to the relevant product data sheet. For further information, please contact our Technical Helpline on

30 Principle 8 Increasing resistivity BS EN 504-9:006 BS EN 504 Principle 8 is concerned with increasing resistivity by increasing the electrical resistivity of the concrete. The resistivity of reinforced concrete may be reduced through the application of external wall insulation, water repellent surface treatments, pore-filling impregnation or surface coatings. 5 Water penetration High moisture content High moisture content on external areas of reinforced concrete leading to reinforcement corrosion. IR Water penetration due to exposed areas of concrete leading to reinforcement corrosion. IR Chloride-contaminated concrete Chloride-contaminated concrete leading to chloride-induced corrosion and delamination of concrete. IR Water penetration Water penetration due to ponding, leading to reinforcement corrosion. IR 4 High moisture content Due to ground water penetration and wick effect on dry concrete, allowing water to saturate the concrete, eventually leading to reinforcement corrosion. RP 5

31 Solution 8 Principle 8: Increasing resistivity BS EN 504-: Surface protection systems for concrete BS EN 504-: Structural and non-structural repair Methods of protection based upon the BS EN 504 Principle 8 is the use of the following: 5a 8. Limiting moisture content by surface treatments, coatings or external wall insulation. Coating 5b Applied to exposed areas of concrete to increase resistivity. weber.cote clear weber.cote smooth weber.cote EC External wall insulation, EWI To provide overcladding to the surface of the concrete to reduce the corrosion rate and protect against water penetration. weber.therm XP see Weber Render Solutions handbook BS EN 504- Hand-applied mortars To replace damaged concrete and increase resistivity. weber.cem HB0 weber.cem HB40 BS EN 504- Sprayed concrete To replace contaminated concrete and to increase concrete cover. weber.cem spray DS weber.cem spray RS weber.cem spray DSF weber.cem spray CP BS EN 504- In-surface impregnation Impregnation of the concrete surface to limit water penetration. weber.tec acrylic sealer BS EN Coating Coating applied to resist passage of water and prevent water penetration weber.cem brushcoat weber.cem coat 5 weber.tec EP coating or EP coating WD Areas of use MC BS EN 504- Buildings Bridges Piers, jetties etc Car parks and more... For detailed instructions, please refer to the relevant product data sheet. For further information, please contact our Technical Helpline on

32 Principle 9 Cathodic control BS EN 504-9:006 BS EN 504 Principle 9 is concerned with cathodic control by creating conditions in which potential cathodic areas of reinforcement are unable to drive an anodic reaction. Cathodic control restricts access of oxygen to all potentially cathodic areas, when corrosion cells are stifled and corrosion is prevented by the inactivity of the cathodes. Marine environments Splash zones to marine jetties, piers and sea walls allows corrosion cells to be initiated, leading to reinforcement corrosion. CC Permeable concrete Permeable concrete allowing oxygen and water to ingress and set up a corrosion cell. CC Corrosion cells Corrosion cells forming at splash zones where water is coming into contact with the concrete. CC 54

33 Principle 9: Cathodic control BS EN 504-: Surface protection systems for concrete Limiting oxygen content by saturation or surface coating Solution 9 Methods of protection based upon the BS EN 504 Principle 9 is the use of the following: 9. Limiting moisture content at the cathode by saturation or surface coating. Marine environments Application of coatings to limit oxygen into reinforced concrete. weber.tec EP coating weber.tec PU sealcoat MC BS EN 504- Coating Application of a defect-free barrier coating to prevent oxygen and moisture getting into the concrete. weber.tec EP coating weber.tec EP coating WD weber.tec PU sealcoat MC BS EN 504- Coating Application of a high-performance elastomeric coating to limit oxygen. weber.cote EC santane EFL MC BS EN 504- Areas of use Buildings Bridges Piers, jetties etc Car parks and more... For detailed instructions, please refer to the relevant product data sheet. For further information, please contact our Technical Helpline on

34 Principle 0 Cathodic protection BS EN 504-9:006 BS EN 504 Principle 0 is concerned with cathodic protection of the concrete structure. This is appropriate where chloride contamination is significant or carbonation has reached the reinforcement resulting in a high risk of corrosion. Impressed current cathodic protection applied in accordance to EN 696 can control corrosion, counteracts the incipient anode effect and can limit the amount of concrete removal. Corroded steel Steel sections corroding within encased concrete, causing reinforcement corrosion and spalled concrete. CP Significant chloride contamination Contaminated concrete due to chlorides, leading to reinforcement corrosion and spalled concrete. CP Extensive carbonation Extensive carbonation of concrete due to low concrete cover and carbon dioxide CO² diffusion, leading to reinforcement corrosion. CP 56

35 Solution 0 Principle 0: Cathodic protection BS EN 504-: Structural and non-structural repair BS EN 696:000: Cathodic protection of steel in concrete Methods of protection based upon the BS EN 504 Principle 0 is the use of the following: 0. Applying electrical potential. Note: Protection should be carried out by CP experts involving CP design to optimise the long-term effectiveness of the system. Recasting concrete Recasting concrete around the steel section using CP grade repair concrete. Five Star repair concrete CP BS EN 504- Concrete repair Using CP grade repair mortar or concrete. weber.cem mortar CP Five Star repair concrete CP BS EN 504- Concrete repair Using CP grade sprayed concrete or repair concrete. weber.cem spray CP Five Star repair concrete CP Areas of use BS EN 504- Buildings Bridges Piers, jetties etc Car parks and more... For detailed instructions, please refer to the relevant product data sheet. For further information, please contact our Technical Helpline on

36 Principle Control of anodic areas BS EN BS EN 504 Principle is concerned with the control of the anodic area by creating conditions in which potential anodic areas of reinforcement are unable to take part in corrosion process. Coatings can be applied directly to the reinforcement to function as anodic inhibitors or to be barriers. Corrosion inhibitors allow migration to the reinforcement and chemically change the surface of the steel to form a protective passive film. Exposed steel Reinforcement will corrode freely if left untouched. CA Exposed steel Reinforcement that is left untreated will corrode and lead to delaminated concrete and spalled concrete. CA Low concrete cover Low concrete cover to reinforcement can lead to anodes setting up in the reinforced concrete and a corrosion cell being set up. CA 58

37 Solution Principle : Control of anodic areas BS EN 504-7: Reinforcement corrosion protection Methods of protection based upon the BS EN 504 Principle is the use of the following:. Painting reinforcement with coatings containing active pigments.. Painting reinforcement with barrier coatings.. Applying corrosion inhibitors to the concrete. Active coating An active coating applied to the exposed reinforcement rebar. weber.cem keycoat CA BS EN Barrier coating A barrier coating applied to the exposed reinforcement rebar to prevent corrosion. weber.tec EP bonding aid CA BS EN Corrosion inhibitor Applied to the concrete surface to chemically change the surface of the rebar reinforcement and protect against corrosion. weber.tec guard MCI weber.tec corroguard CA Areas of use BS EN Buildings Bridges Piers, jetties etc Car parks and more... For detailed instructions, please refer to the relevant product data sheet. For further information, please contact our Technical Helpline on

38 Summary Lecture summary Introduction of the course (Course syllabus) Repair terminology Concrete repairs EN The phases of a typical repair projects Next Lecture Preparing structures for durable repairs Concrete surface Reinforcement hazardous materials