Bridge Maintenance and Repair

1. Bridge Maintenance and Repair

2. Preventative Maintenance Objectives • Preserve investment • - Cost of replacement higher than initial cost • - Repair costs increase with time • Safety and avoidance of catastrophic failure • Maximize life of bridge

3. PREVENTATIVEMAINTENANCEISCOST EFFECTIVE!

4. General Methods - Concrete • removal and replacement of deteriorated concrete • filling cracks • coating and sealing concrete surface

5. General Methods - Steel • protect it from exposure to electrolytes • painting • galvanizing

6. General Methods - Timber • control moisture content of the wood

7. Bridge Seats and Caps • Runoff through deck joints contains debris and de-icing chemicals • de-icing chemicals that accumulate on substructure cap can result in: • corrosion of reinforcing steel and spalling concrete • corrosion of bearing assembly (i.e. “frozen bearing”)

8. Bridge Seats and Caps (cont’d) • Proper maintenance • regular cleaning of substructure caps and deck joints with high pressure pump • provide drainage troughs below deck joints • surface protective coatings on bearing systems

9. Substructure - Concerns • Material deterioration • wet/dry and freeze/thaw cycles • abrasion by water/ice at waterline • steel corrosion • concrete spalling • decay and vermin attack on timber • Ground settlement

10. Substructure - Concerns (cont’d) • Impact damage • Other damage • pressure exerted on the piers and abutments by the earth

11. Substructure - Maintenance • Material deterioration • protective coatings • preservatives • Foundation settlement and earth pressure • subsurface drains • struts • regrading soil profile

12. Substructure - Maintenance (cont’d) • Impact damage • guard rails and energy dissipaters • fenders or steel plates on abutments and piers

13. Superstructure - Concerns • Usually very difficult to access, so problems are frequently overlooked • Deterioration occurs with time • salt and chemicals - cracks in concrete • corrosion - frozen bearings • carbonation and sulfation • Impact damage • high loads • ice and drift

14. Superstructure - Maintenance • Inspection • Good protection system • coatings - preservatives • sealers - patching • paints - crack filling • Pressure washing and cleaning • Strengthening

15. Deck • Most susceptible to deterioration • de-icing salts, acid rain • ultraviolet rays • mechanical abrasion • Requires a lot of maintenance and repair • Protects rest of structure

16. Concrete Decks • De-icing salt is main menace • causes reinforcement to corrode • concrete spalls • potholes

17. Concrete Decks (cont’d) • Design and construction features to control deterioration • optimum cover for reinforcement • good drainage - silica fume • smaller skews - low w/c ratio • thicker slabs - good consolidation • air-entrained concrete - low shrinkage

18. Concrete Decks (cont’d) • Main preventative maintenance goal is to control salt and moisture penetration • keep deck clean and drains operating properly • add drains in low spots • monitor deck for chloride contamination • fill cracks • asphalt sealing • polymer overlays • concrete sealers • bituminous concrete overlays with waterproof membrane

19. Curbs & Railings • Deteriorate with time • cracking and spalling - corrosion • salt damage - collision • Replacement can be minimized • appropriate sealers, coatings and paint • galvanized steel

20. Deck Drains • Can cause hazardous traffic situations • Can lead to deterioration of deck and other bridge elements and erode the soil backfill

21. Deck Drains (cont’d) • Typical problems include: • ponding of water on bridge deck • poor drainage allows de-icing salts to deposit on deck and other bridge elements • plugged downspout will burst in freezing weather • Regular cleaning is best maintenance

22. Approach Road • Approach bump • Guardrail • connection to bridge rail • transition stiffness (standard drawing S-1471 & S-1472) • Drainage • trough drains

23. Approach Road (cont’d) • Erosion of headslopes and ditches • Signing • vertical clearance • load limit • delineators

24. Streams and Channels • Erosion control • Slope protection • Bank protection • Rip-rap • Drift • Beaver dams

25. Bridge Major Maintenance and Rehabilitation • Total deck replacement • Partial-depth deck replacement • Delamination repair • Deck overlays • Cathodic protection • Deck joint replacement • Bearing replacement

26. Culvert Major Maintenance and Rehabilitation • Strutting • Culvert liners • Culvert end treatment repair and replacement • Cathodic protection

27. Repair Materials • Concrete • silica-fume concrete • fibre reinforced concrete • latex modified concrete • corrosion-inhibiting concretes

28. Repair Materials (cont’d) • Polymers • polymer concretes • polymer overlays • Specialty products • patching materials • grouts • sealers

29. Approved Products • Standard testing procedures • Certified laboratories • Testing paid by manufacturer • Approved products list • concrete sealers • concrete patching & grouting • paints

30. Concrete Sealers • Type 1a - relatively dry deck RMC < 55% • Type 1b - outdoor exposure deck RMC < 70% • Type 1c - outdoor exposure deck RMC < 80% • Type 2a - one component coating RMC < 70% • Type 2b -two component coating RMC < 70% • Type 3 - pigmented coating RMC < 70%

31. Concrete Patching Materials • Type NH • poured horizontal patches, 3 day curing • Type OH-V • trowelled overhead or vertical patch • Type LTH • low temperature poured horizontal patch • Type HEH • high early strength poured horizontal patch

32. Paints • Type B2 • Truss / River / Little experience • Type B3 • Girder / River / Much experience • Type B5 & B6 • Freeway / Overpass • Type 8 • Submerged pipe piles