1. Power Washing and Overcoating is Effective and Much Less Expensive than Sandblasting and Completely Repainting a Bridge by
Wayne Senick, Technical Director
and
Craig Ballinger, P.E.
Termarust Technologies
Abrasive Blasted
High Pressure Water Cleaned

2. Advantages of Abrasive Blasting and High Pressure Water Cleaning
Removal Of Lead based paint
Prepare surface for zinc based coating
Cosmetics
HPWC
Effectively cleans structure critical crevice corroded connections
Cost effectively removes Non Visible contaminants
Provides a stable substrate for over coating
Potential for at least 50% project cost savings

3. 1 yr old 3 coat zinc epoxy urethane over pack rust
These Crevice corroded connections were not washed before coating to remove the active salts, not chemically treated to neutralize the active corrosion causing chemistries and were then sealed - which created an oxygen concentration cell and failure occurred
1 yr old 3 coat zinc epoxy urethane over pack rust

4. Crevice Corroded Connection Washed before Abrasive Blasting and Coating
to remove the active salts
chemically treated with HR CSA penetrant to neutralize the active corrosion causing chemistries
sealed up with a top coat based on HR CSA* neutralization chemistry
Coating failure has not occur in 18 years
*HR CSA (High Ratio Co-Polymerized Calcium Sulfonate)
Crevice Corroded connections treated with an HR CSA* corrosion control coating on the High Level Bridge Edmonton, Alberta, Canada after 18 years the crevice corrosion has been stopped

5. Pack rust and Crevice corrosion can overstress structural connections

6. This structure has coating failure in the joints and connections, caused by severe crevice corrosion and pack rust, but the coating on the flat surfaces is relatively intact

7. Grit recycling unit and air mover with bag house
Typical Recycling Equipment and Negative Air Containment used in Abrasive Blasting and Lead Removal Operations
Grit recycling unit and air mover with bag house
Two complete negative air grit recycling systems with air compressors hooked in a train to be towed down the bridge as the containment moved
Two example of negative air containments

8. Water Collection, Containment and Surface Preparation Equipment for HPWC Lead Removal Project
Shrink wrapped water tight ultra-light water collection containment
7000 PSI 6 Gallon per minute hot Water HPWC Unit with salt remover injector
Movable flow thru tap system to contain paint chips and liquid water
PSI HPWC Units and Injector for Soluble Salt Remover

9. Complete Water Recycling and Filtration System on 100,000 square foot Bridge Project
Pressure pumps to supply head pressure of 15 PSI for wash pumps
Fresh and filtered water storage
Settling Tank, Skimmer and Feed Pumps for Filter System
Water passes thru 5 and 1 micron particle filters before going to storage for re use

10. Typical High Pressure Water Cleaning Surface Preparation Sequence with Adhesion Testing and Testing for Non–Visible Contaminants
High Pressure Water Cleaning using 5000 PSI, zero degree rotating tip, a 4 inch stand off distance
Removal of black oxides by hand or power tool cleaning
Adhesion Testing using a Hydraulic Pull-off tester, 300 PSI minimum for over coating, 300 hundred tests per 100,000 sq ft. Photo courtesy Ministry Transport Ontario
Testing for Non Visible Contaminants before coating application

11. Where are the costs
Removal of lead based coatings by abrasive blasting and ultra high pressure water jetting micronizes the lead dust which makes it breathable and absorbable by plants.
The containment for abrasive blasting is heavier and more expensive to construct because of the weight of the abrasive and the need for negative air pressure to facilitate environmental protection
The surface needs to be washed to mitigate salts and the water must be collected. The washing step must be done, the water must be removed, and containment dried before blasting can take place
The equipment required to contain, abrasive blast, collect and recycle the abrasive is much more expensive to buy and operate than a high pressure water cleaning system.

12. Adhesion of Remaining Substrate
If stressed by HPWC (High Pressure Water Cleaning) at a minimum 5000 PSI with a zero degree rotating tip at a maximum 4 inch stand off distance specified, adhesion testing in the field has shown that this surface preparation method consistently will produce adhesion values over 300 PSI for the remaining coating.
The owner should specify a minimum adhesion value no less than 300 PSI and adhesion testing must be done before coating is applied.
The number of adhesion tests should be written into the specification. For example: a minimum of 300 tests per 100,000 square feet or whatever the engineer deems necessary based on the condition of the existing prepared substrate
Field experience has shown a hydraulic pull off tester meeting ASTM D4541delivered the most consistent results

13. Test Site Photos and Adhesion Test Log Sheets
Site 24, Photo IM000824, 825 PSI
Site 33, Photo IM00833, 450 PSI

14. Test Site Photos and Adhesion Test Log Sheets
Site 163, Photo IM001000, 720 PSI
Site 179, Photo IM001022, 340 PSI

15. Cost Savings Case Histories Rail Bridge 260,000 square feet
Total removal of lead based coating system
Negative air containment
Collection, recycling or disposal of abrasive
Standard 3 coat zinc epoxy urethane coating
Bid price 7.6 million
No warranty provided
High pressure water cleaning and over coating
Collecting the lead paint and recycling the water
High performance single coat HR CSA coating system
Bid price $4.3 million
5 year warranty including crevice corroded joints and connections
Cost Saving including a 5 year warranty = $3.3 million

16. Contractors Actual Cost Savings Analysis as Proposed to Owner Abrasive Blasting - 3 Coat Zinc System vs High Pressure Water Cleaning - HR CSA Coating System
Specified
Air and dust impenetrable enclosure
Alternative
Flow through tarps will trap paint chips and liquid water Cost saving
Mechanical ventilation system to protect workers sufficient to achieve a negative air environment within the enclosure
Not required – no lead dust generated Cost saving
Exhaust ventilation system to provide filtration of the exhaust air
Weekly instrument testing to verify airflow and negative pressure inside containment
Not required – no pressurized containment Cost saving
Air lock entry wall
Not required – no lead dust to contain Cost saving

17. Cost Savings “Continued”
Specified
Cleaning and securing of containment at the end of workday
Alternative
Not required – no lead dust to blow around Cost saving
Daily assessment of visual emissions
Not required - no lead dust generated Cost saving
Full time or part time high volume ambient air monitoring
Not required – no lead dust generated Cost saving
Packaging, storage, transportation, and disposal of waste generated by the project
Reduction of generated solid waste, approximately 1300 tons.
in addition, no waste solvent, paint cans or catalyzed paint to dispose of Cost saving

18. Cost Savings “Continued”
Specified – coating system
Stripe coat zinc
1st layer zinc
2nd layer epoxy
3rd layer k urethane
Alternative
Penetration for joints and connections
Caulk coat + spot prime
Plus 1 layer wet on wet, instead of three
Separate coats with curing time Cost saving
Specified
Caulking
Sealing of joints included in coating operation Cost saving
Specified – surface preparation
SSPC-SP10 near white blasting and
SSPC-SP7 brush-off blasting
Not required Cost saving
Measure the surface profile of blast cleaned surfaces
Not required – coating not profile sensitive Cost saving

19. Cost Savings “Continued”
Specified
Specified time restriction between cleaning and painting
Alternative
Not required – flash rust not an issue Cost saving
Containment during coating application
Containment not required for purpose of environmental protection or for a safe working environment.
As coating is not hazardous, will contain overspray with flow through tarps. Cost saving
Specified – recoat time
Apply each coat after previous coat has been allowed to dry
All successive coats can be applied wet on wet Cost saving
Specified – caulking
Caulking shall be applied to crevices not sealed, after the application of the second intermediate layer.
Manufacturer’s note – Caulking must be allowed to cure for 5 – 8 days at 23ºC and 50% R.H.
Caulk not required Cost saving
Warranty 2 years or 5 years – separate price
5 year warranty included Cost saving

21. Time Value of Money Example of one Owner’s use of the cost
savings from HPWC are as follows:
Cost saving will be invested during the 5 year warranty period ( shown on chart )
On going maintenance program will be funded with earned interest
After the 5 year warranty period the saved capital can now be used to fund another project

22. Case History Highway Bridge 100,000 square feet
Total removal of lead based system
Negative air containment
Collection, recycling or disposal of abrasive
Standard 3 coat zinc epoxy urethane coating
Bid price 3.5 million
No coating system performance warranty available
High pressure water cleaning and over coating
Collecting the lead and recycling the water
High performance single coat HR CSA coating system
Bid price 1.2 million
5 year warranty including crevice corroded joints and connections
Cost Saving including a 5 year warranty 2.3 million dollars

23. Example Specification Surface Preparation
SURFACE PREPARATION AND CLEANING:
High Pressure Water Cleaning - The structure (or the portions of it to be coated) are to be cleaned using a 7,000 psi 6 Gal/Min hot water HP WC (high-pressure water cleaning)– with a zero degree rotating tip (at a maximum of a 4” standoff distance) to a (SSPC –SP12 WJ4- NV2 ) to remove loose paint and loose rust (SSPC SP2 &SP3 hand or power tool cleaning maybe used in inaccessible areas or when water cleaning is not possible). In some cases after HP WC there are areas of tightly adhered black oxide which was not removed. This tightly adhered black oxide even though it meets the WJ4 standard (and the active corrosion under it) is highly contaminated with Chloride &/or Sulfates &/or Nitrates and if allowed to remain, will result in delamination of the black oxide substrate and the coating which has adhered to it and must be removed.
Crevice Corroded Joints and Connections
When using a 7,000 psi 6 Gal/Min hot water HPWC (high-pressure water cleaning) with a zero degree rotating tip (at a maximum of a “4” standoff distance) to a (SSPC –SP12 WJ4- NV2) The jet must be focused right on the crevice corroded joints and connections to flush them thoroughly. In addition to properly clean the joints and connections a soluble salt remover must be incorporated into the wash water. A minimum 100:1 solution of Chlor*Rid (manufactured by CHLOR*RID International (USA) or (CDN) or equivalent is required to remove as much salt from the joint as possible. This is mandatory when preparing crevice corroded joints and connections for treatment with the HR CSA Penetrant/Sealer and HR CSA Primer/Topcoat System.
NV (Non Visible Contaminants) When it is expected (and/or confirmed by testing) that the surface of the steel is contaminated with soluble salts (Chlorides &/or Sulfates &/or Nitrates) – the HP WC (high pressure water cleaning) should be finished with or incorporated into the wash water initially a 100:1 solution of Chlor*Rid (manufactured by CHLOR*RID International (USA) or (CDN) or equivalent to remove those salts. (Just washing with water is not adequate because the salts are chemically & polar attracted to steel) [For additional information on this topic please access chlor-rid’s website]
DRYING: It is required that even if the joints and connections look dry - that they be blown dry with
clean, DRY, oil free, high pressure ( 100 psi) compressed air.

24. Example Specification Key Points
Testing to determine whether or not wash water is hazardous
If water is hazardous - establish a collection and recycling or disposal system
Collection of any hazardous material including paint chips
Do adhesion test to verify surface preparation has been done correctly
Do testing to determine non visible contaminants have been removed to acceptable levels

25. Conclusion
High Pressure Water Cleaning and a HR CSA coating system is a cost effective alternative to Abrasive Blasting especially on structures with structure critical crevice corroded and pack rusted joints and connections
In most cases washing is now specified for all painting projects for removal of non-visible contaminants
The condition of the existing coating is not an issue as the HPWC surface preparation will remove any coating not suitable for over coating as proven by adhesion testing done in the field
The cost saving can be used to fund other projects or invested to fund the long term maintenance of the structure especially for private owners and toll authorities.