Coatings

VDOT’s Laser Coating Removal Research [2018-11-13]

The Virginia Department of Transportation is conducting research investigating the efficacy of using high-wattage lasers for removing coatings from existing bridges. High-wattage, hand-held lasers are now commercially available at costs that have increased their potential value for use in removing coatings on bridges. The objective of this project is to determine the feasibility of using high-wattage lasers to remove coatings from VDOT bridges.

Download VDOT Laser Coating Removal Research Document (Revised) (.pdf)

Scan 15-03: Successful Preservation Practices for Steel Bridge Coatings

Coatings provide the primary corrosion protection system for steel highway bridges. Currently, there are approximately 610,000 highway bridges in the U.S., of which about 180,000 are constructed from steel. Although steel bridges are still being built, the majority of steel bridges were constructed between 1920 and 1970. In recent years, the construction of new highway mileage has slowed and the use of concrete for construction of new bridges has increased. These factors indicate that the primary issues regarding steel bridge coatings lie with maintenance of the many existing—and aging—inventory of steel bridges. The median age of the existing inventory now exceeds 40 years, and a large percentage of coating systems protecting steel bridges have met or exceeded their useful service lives. There is currently an increasing demand for maintenance and replacement of coating systems on steel bridge structures.

Download Scan 15-03-Rev 2.1 (.pdf)

Successful Preservation Practices For Steel Bridge Coatings

The NCHRP 20-68 program panel has approved the final Scan 15-03 report titled “Preservation Practices for Steel Bridge Coatings”. The report investigates leading practices for corrosion mitigation through coating management and re-coating and associated management of environmentally hazardous materials.

Download NCHRP 20-68 Scan 15-03 Final Report (.pdf)

Chloride Contamination Remediation of Steel Bridges

Researchers evaluated 32 steel surface preparation methods to determine how effectively they remove chloride from corroded chloride-contaminated steel panels. Wet methods proved more effective than dry methods. The three most effective wet methods injected mineral slag abrasives in a water stream and resulted in less than 1% chlorides remaining. Most dry surface preparation methods left significantly more chloride contamination after surface preparation. The three most effective dry methods used multiple blast cleaning cycles. These methods approached the effectiveness of the best wet methods, with 1.6 to 2.0% chlorides remaining. The least effective surface preparation was a single abrasive blast cleaning with a 40/50 steel grit mix. This resulted in 6.5 % chlorides remaining. No surface preparation method evaluated resulted in chloride contamination less than 5 μg/cm2. Analyses with scanning electron microscopy revealed that the remaining chloride contamination (5.3 to 23.9 μg/cm2) was randomly deposited in individual hot spots distributed across the steel’s surface. This contamination would probably cause premature coating failure. Wet methods are significantly more effective than a single abrasive blast cleaning, irrespective of the abrasive material type or grit size used. Although, multiple iterations of blast cleaning approached the effectiveness of the best wet methods.

Download the Report (.pdf)

Painting Bolted Connections for Bridges

Kenneth Trimber, President of KTA-Tator, Inc., has published an article on “Painting Bolted Connections for Bridges”.

Download the Article (.pdf)

Aesthetic Coatings for Steel Bridge Components

The Wisconsin DOT has published a report summarizing the effectiveness of aesthetic coating systems for steel bridges. Twelve 2-coat, 3-coat, and duplex coating systems were selected and subjected to a series of accelerated weathering and mechanical tests to determine their performance. The performance evaluation was made by considering gloss and color retention, coating discontinuities, rust creepage, and coating adhesion. Surface preparation and coating application procedures were given significant consideration. The best color and gloss retention were achieved by the 3-coat fluoropolymer systems, but the materials had higher costs. One of the two 2-coat systems performed nearly the same as the 3-coat polyurethane coating systems and the other performed poorly with significant color fading. Duplex polyurethane systems showed comparable performance to that of the 3-coat fluoropolymer systems but they performed better than the 3-coat polyurethane systems. This was primarily due to the added corrosion protection provided by the hot dip galvanization. The study found that proper adhesion in a duplex system can be achieved by following appropriate procedures for galvanization and surface preparation. Both duplex powder coated systems tested in this study experienced out-gassing problems during the initial application and did not perform satisfactorily.

Download the Final Report (.pdf)

Premature Paint Failure

Ross Hammock of the Florida DOT has prepared a 21-slide presentation (.pdf) on “Preventing Premature Coating Failure”.  Additional documents available include a 90% “Punch-list” (.pdf) to accompany a Paint / Construction Inspection Review, and a 1-page Bridge Inspection Report (.pdf).

Download the following documents:

• 21-Slide Presentation (.pdf)
• 2-Page 90% Punch-list (.pdf)
• 1-Page Bridge Inspection Report (.pdf)

National: NBPP Steel Bridge Coatings Group Strategic Plan

The Strategic Plan for the AASHTO TSP2 National Bridge Preservation Partnership (NBPP) Coatings Group is a guide to help NBPP Coatings Group members serve the needs of the highway bridge community by promoting the development of long term, cost effective re-coating methods for the prevention and / or mitigation of corrosion of steel bridge structures to protect their performance and extend their service life. The draft Strategic Plan may be downloaded as a (.docx) file at:

Download the Draft Strategic Plan (.docx)

SEBPP: Bridge Painting Report, Tool, and PowerPoint

The Southeast Bridge Preservation Partnership’s Paint Working Group has completed a report, developed a tool, and assembled a PowerPoint presentation on bridge painting. Download the Task Force’s products:

• SEBPP 2014 Bridge Repainting Report
• SEBPP 2021 Bridge Paint Cost Analysis Tool
• SEBPP Bridge Paint Survey Results
• SEBPP Outstanding Needs from 2012-11-12 Survey
• SEBPP 2013 Paint Survey Presentation
• SEBPP 2013 Paint Report Presentation

Spot Painting for Bridge Preservation

The University of Kentucky has completed a research study that provides guidance on materials, means, and methods of bridge spot painting to address problems from leaking joints and widespread use of deicing salts.

Read an Article Describing the Study

Surface Preparation of Soluble Salt Contaminated Steel Substrates Prior to Coating

The subject of soluble salts on steel substrates and their effect on coating performance is an important and widely debated topic. The concentration at which soluble salts begin to have a detrimental effect on coating
performance varies widely, depending on factors such as the type of service, coating thickness, generic coating type, and the presence of moisture.

NACE International has prepared a Technical Report (Publication 6G186) that offers guidance in this area.

Download NACE International Publication 6G186

Environmentally Acceptable Materials for the Corrosion Protection of Steel Bridges

This report presents results of long-term natural exposure testing of several high- and low-volatile organic compound (VOC) coating systems.  The corrosion control performance of several environmentally acceptable coating systems was evaluated through panel exposures at a seaside exposure site and on bridge structures.  This report also includes an economic analysis of painting alternatives and a discussion of VOC-compliant coating technologies.  The report is intended for use by bridge engineers who are required to comply with changing regulations affecting bridge painting operations.

Read the Report (.pdf)

Pulse Electro Thermal Deicing

Tiny bursts of electricity could be used to prevent dangerous ice buildup on South Carolina’s Arthur Ravenel Jr. Bridge cables if the state receives funding for the project from the Federal Emergency Management Agency.

Read the Post and Courier (Charleston, SC) Article

Cost of Corrosion Study Unveiled

The U.S. Federal Highway Administration (FHWA) released a break-through 2-year study in 2002 on the direct costs associated with metallic corrosion in nearly every U.S. industry sector, from infrastructure and transportation to production and manufacturing. Initiated by NACE International and mandated by the U.S. Congress in 1999 as part of the Transportation Equity Act for the 21st Century (TEA-21), the study provides current cost estimates for the time and identifies national strategies to minimize the impact of corrosion.

The study, titled “Corrosion Costs and Preventive Strategies in the United States,” was conducted from 1999 to 2001 by CC Technologies Laboratories, Inc., with support from the FHWA and NACE. Its main activities included determining the cost of corrosion control methods and services, determining the economic impact of corrosion for specific industry sectors, extrapolating individual sector costs to a national total corrosion cost, assessing barriers to effective implementation of optimized corrosion control practices, and developing implementation strategies and cost-saving recommendations.

Read the Paper (.pdf)

Customized Solutions for Bridge Coating / Corrosion Projects — Lessons Learned

The service lives of coating systems are affected by different bridge site conditions such as humidity, temperature, presence of salt (chlorides, sulphates, and nitrates), exposure to ultraviolet radiation; rock chips and direct salt spray. Many state agencies across the US face the challenge of achieving long service lives from their bridge coating systems.

A paper presented at the 9th International Conference on Short and Medium Span Bridges held in July 2014 at Calgary, Alberta, demonstrates the lessons learned over time in designing coating/corrosion protection systems to increase performance and minimize future long term maintenance costs.

Read the Paper (.pdf)

Field Methods for Determining Lead Content in Bridge Paint Removal Waste

The New York State Department of Transportation has sponsored a study to develop field methods for determining lead content in bridge paint removal waste. The study’s final report was published in December 2013 and may be downloaded as a (.pdf) file at:

Download the Final Report (.pdf)

A 2008 Evaluation of Missouri DOT’s Coating Programs

In 2008, the Missouri DOT produced an in-house report that evaluated the state’s coatings programs.

Read the 2008 Report

Preliminary Assessment of Procedures for Coating Steel Components on Virginia Bridges

The Virginia DOT (VDOT) has conducted a preliminary assessment of Virginia’s bridge coating practices to identify areas where process improvements and/or cost savings could be realized. The
assessment included reviewing VDOT’s coating procedures, coating performance, and costs associated with bridge coating work, including containment systems, surface preparation techniques, and coating systems. In addition, information on bridge coating products and programs from bridge coating industries and organizations was gathered.

The study found that the predominant methods VDOT uses to prepare and coat steel bridge components are adequate and are consistent with industry and compliance standards. These methods include dry abrasive blasting and the use of power tool cleaning for surface preparation; conventional full containment that achieves minimal emissions; and use of a three-coat
zinc-based coating system. However, enacting changes in some of the preliminary work for a bridge coating project could improve VDOT’s coating process and potentially reduce costs. These changes include providing additional guidance for coating treatment decisions and preventive maintenance; providing contractors more project scope details in the bid and contract documents; and requiring discussion of job-specific tasks in the preconstruction meeting.

Combining the data from Site Manager and the Pontis Structure Inventory appears to be an efficient means of evaluating expenditures and trends. Analyzing costs for recoating work (VDOT’s most common coating method) can be expedited by using “bridge deck area” (a field in the Pontis Structure Inventory) rather than “steel tonnage” (which must be drawn from individual contracts).

Download the Manual (.pdf)