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Cold Spray for Steel Bridges


I. Problem Title: Cold Spray for Steel Bridges

II. Research Problem Statement: Cold spray is an effective way of depositing structural metals and functional surfaces. There are three potential areas of benefit for steel bridges, each of which requires a robust, cost superior solution that considers all cost factors (material, labor, downtime, and durability of repair):

• Corrosion protection - It is well established that zinc provides good cathodic protection for steel structures. Application methods for large bridge components include paint and thermal spray (galvanizing is not well suited for large bridge components). Zinc paint is recognized as a cost-effective bridge coating, but its durability is limited. Thermal spray (also known as metallizing) is considered by many to be superior paint, but it is costly. Specifically, thermal spray requires special blast cleaning, precluding the use of blast cabinets and requiring hand blasting. Cold spray offers opportunities with reduced surface preparation and with effective deposition of zinc as well as other potentially more effective materials for galvanic corrosion protection. Cost savings can be realized from both the reduced surface preparation costs as well as the longevity of the corrosion protection. In order to realize these potential benefits, there is a need to develop, mature, and demonstrate Cold Spray technologies.

• Surface conditioning - Steel bridge surfaces often require conditioning to satisfy structural performance needs and owners expectations, and such conditioning can be costly. The surface of steel structures can experience recession over time due to either corrosion or wear requiring replacement or repair. The new part or surface will then be subject to the same degrading process. Steel and steel alloys can be applied effectively by Cold Spray. With proper material and process selection, the cold spray process can produce high integrity bonds, high deposited material strength, and minimal structural impact on the substrate material. In addition, proper material selection can provide a more durable surface requiring fewer future repairs. As with corrosion, there is the need to develop and demonstrate Cold Spray methods focused on improved surface conditioning.

• Deck surfacing - It is difficult to obtain cost-effective long life from steel bridge deck coatings. It is considered that orthotropic deck structures can provide a 100 year life, but typically decks require replacement within 10 to 15 years. With optimized materials selection and process development, Cold Spray can apply a wide range of metals and alloys for deck resurfacing. Additionally, the process can be performed in a cost superior way compared with existing technologies when considering all cost factors. Similarly, while there is potential, the details of the approach must be developed.

III. Research Objective: Research would include testing and analysis to develop, mature, and demonstrate Cold Spray solutions for these service problems, and then compare those solutions with conventional solutions currently in place or other alternate options.

• Anodic corrosion protection through cold spray deposition compared to zinc paint and thermally sprayed zinc (wire arc or similar current method) o Ease of application and automation

• Cost of application (materials, surface preparation, deposition)

• Cost savings due to longevity of protection

• Resurfacing or repairing surfaces of structural steel components compared to welding or hardware replacement

• Effect on overall strength of the structure

• Bond integrity and deposited material mechanical properties

• Cost of application (materials, surface preparation, deposition)

• Cost savings due to extended life

• Cold spray applied deck surfacing materials compared to traditional steel deck coatings

• Functional properties of deposit

• Ease of application and automation

• Cost of application (materials, surface preparation, deposition)

• Cost savings due to extended life

The research would also conduct structural testing of steel elements that have been built-up by cold spray.

IV. Estimate of Problem Funding and Research Period

$350,000, 2 years

V. Urgency, Payoff Potential, and Implementation

TBD

VI. Person(s) Developing the Problem Statement

Ronnie Medlock VP - Technical Services High Steel Structures, Inc.

phone: 717.209.4647

email: rmedlock@high.net


Sponsoring Committee:AKC70, Fabrication and Inspection of Metal Structures
Source Info:Ronnie Medlock
VP - Technical Services
High Steel Structures, Inc.
phone: 717.209.4647
email: rmedlock@high.net
Date Posted:05/05/2013
Date Modified:05/07/2013
Index Terms:Steel bridges, Corrosion protection, Bridge decks, Zinc, Cathodic protection, Costs, Service life,
Cosponsoring Committees: 
Subjects    
Highways
Construction
Maintenance and Preservation
Materials
Bridges and other structures

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