Theodore Hopwood Ii

Inspection, Prevention, and Remedy of Suspension Bridge Cable Corrosion Problems

This report discusses methods for visually inspecting cable suspension bridges for corrosion damage. The report discusses how to plan and perform such work, including the locations on cables where corrosion damage is likely detected. The report also provides recommendations for assessing the condition of suspension bridge wire. Recommendations also are included for remedial cable repair work should corrosion damage be detected.

ACOUSTIC EMISSION MONITORING OF WELDMENTS

Weld tests were performed on low-carbon and high-strength, low-alloy steel weldments. The weldments were monitored with an acoustic emission detector during both the “in-process” and the “in-cooling” phases of the welding operation. Artificial defects were induced in several of the welds to promote cracking. Some high-strength weldments were designed to produce welds subject to high restraint. Nondestructive and destructive evaluation of the completed weldments revealed that high acoustic emission activity during in-cooling could be correlated with embedded defects and cold-cracking. Copious emission activity was also detected from unflawed weldments. Acoustic emissions were detected in high-strength steel weldments for periods up to 265 h. However, there was no clear relation between the duration of acoustic emission activity and cracking. On a per-electrode-deposited basis, high-stressed welds produced more emissions than low-stressed welds.

Disposal of Bridge Paint Residue

Paint residue generated by bridge maintenance painting commonly contains lead requiring the residue to be disposed of as a hazardous waste. Several alternatives are being investigated in this study, chemical stabilization and recycling as options for the Kentucky Transportation Cabinet (KYTC) to consider in addressing the waste stream generated by bridge maintenance painting operations. In the initial portion of this study, four chemical stabilization materials were identified as candidates for experimental/demonstration projects entailing maintenance painting. A recycling option was also provided. An experimental bridge painting project was led by KYTC to investigate the use of two chemical stabilizers and the recycling option. The results of that effort are discussed including chemical analyses, progress of work, and resulting costs. Recommendations are provided for additional testing of chemical stabilizers.

Experimental concrete coating application on the median barrier of I 65 in Louisville.

The objectives of this research were to evaluate the experimental protective coating that was applied to approximately 1,200 linear feet of concrete median barrier along the paving project on a section of I 65 between mile points 131.289 and 136.421 in downtown Louisville. The project was completed generally in accordance with the specifications and special notes. This experimental project is the first trial of concrete coatings identified under KYSPR 05-271 Coatings, Sealants and Fillers to Address Bridge Concrete Deterioration and Aesthetics-Phase 1. The coatings systems identified under that study were intended to provide improved protection and aesthetics for reinforced concrete. This project proved that one candidate coatings system could be applied successfully on existing concrete. It is recommended that KYTC further pursue use of this knowledge by conducting more experimental/ prototype projects to further investigate how coatings hold up on new and old concrete barriers.

Environmental impacts of bridge cleaning operations.

Cleaning (washing) operations of existing leaded paints on bridges were studied to determine the level of lead contamination in the resulting wastewater. Twelve experimental overcoating projects were let on bridges with various types of existing paint in varying states of deterioration. The projects employed different washing pressures ranging from 2500 psi to 10,000 psi and various wash nozzles (fan and 0 deg spinner tips). Kentucky Transportation Cabinet standard filtration was used on 10 projects and 2 projects used an experimental filtration unit having a sand filter and two types of chemical filter media. Prior to painting, the existing paint was analyzed for thickness, adhesion, and lead content. Wastewater generated during maintenance painting operations (potable, unfiltered and filtered) was sampled and analyzed for lead content (total and dissolved), total suspended solids and pH. No clear correlations were obtained between lead in the wastewater, wash pressures, nozzle type, or any of the existing paint parameters tested. The sand filter and chemical filter media of the experimental filtration unit provided significant removal of lead from wastewater.

Kentucky Transportation Cabinet moves Its bridge painting into the 21st century

The Kentucky Transportation Cabinet (KYTC) is rapidly evolving its bridge-painting operations to address the diverse challenges of the 21st century. At the forefront of this effort is the KYTC Paint Team, a multi-disciplinary task force of KYTC personnel representing the KYTC divisions involved in paint activities as well as researchers from the Kentucky Transportation Center (KTC) at the University of Kentucky. Key features of the Paint Team are its close interagency cooperation within KYTC on all facets of bridge painting and the total integration of KTC researchers’ work in Paint Team activities, including laboratory work and field testing. The Paint Team works to achieve incremental improvements on all painting projects. Current Paint Team goals to advance KYTC painting operations include enhancing environmental and worker safety compliance on all projects; improving contractor quality and KYTC field inspections; employing cost-effective bridge-painting options to better address project needs; testing and developing promising new coatings and related technologies; improving project delivery; sharing information with peer groups; and committing to context sensitivity on all bridge-painting projects. This innovative approach has enabled the KYTC to successfully progress and to grow its activities in a field that is beset with technical and regulatory impediments. It is a model that can be used to address highway issues and is amenable for adoption by other transportation agencies.

ENVIRONMENTALLY SAFE PROTECTIVE COATINGS FOR STEEL STRUCTURES - NEW CONSTRUCTION AND MAINTENANCE PAINTING

The purpose of this study was to: 1) assist the Kentucky Transportation Center (KyTC) in identifying protective coatings for structural steel that would meet current and pending environmental regulations, and 2) evaluate overcoating procedures that would be cost-effective and provide regulatory (OSHA and EPA) compliance. A coatings research program was conducted that included: 1) laboratory accelerated corrosion/weathering tests, 2) field exposure tests, and 3) experimental maintenance painting of entire bridges by overcoating. Each of those tasks was intended to address different issues. Regulations concerning volatile organic compound limits for coating systems used in new construction were studied and recommendations provided to KyTC on new systems that would provide potential advantages in application and performance. The laboratory testing was used to evaluate seven candidate overcoating systems and three new construction coatings systems. Field exposure tests consisted of coatings patches applied to bridges and scrap steel. Those tests provided useful information concerning the durability of candidate maintenance coatings and the practicality of experimental application procedures. Eighteen complete bridge maintenance painting projects were conducted for the KyTC experimental overcoating program that employed experimental specifications and coatings systems. Those projects were inspected prior to, during and subsequent to completion. Long-term performance of most projects has been very good.

Stress Evaluation of Welded Steel Bridges on Coal-Haul Routes

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . TABLE OF CONTENTS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ii LIST OF FIGURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . iv LIST OF TABLES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v NOMENCLATURE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi EXECUTIVE SUMMARY . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vi

SURVEY OF CURRENT BRIDGE PAINTING PRACTICES AND RELATED LITERATURE SEARCH

A survey on current bridge painting practices was conducted. Questionnaires were sent to all 50 state highway agencies concerning their present bridge painting practices, changes in those practices that they anticipate due to environmental regulations, and new or experimental painting practices they are investigating. Forty-three responses were received. Those are collated and presented in the appendices along with comments of the responders. A literature search was conducted on publications related to painting of steel structures (since 1987). Forty-nine documents were identified as being relevant to the topic. Those documents are listed in bibliographic form in the appendices.

Modular Expansion Joints and Deck Drains

Inspections were conducted on bridge modular expansion joints and deck drains to assess their performance. Fourty-four modular expansion joints were inspected including 38 Wabo-Maurer and 16 Acme joints. Twenty-three elastometric dams were also inspected fi=or comparative purposes including 21 Transflex dams and 2 Fel-Span units. The joints were rated using a quantitative subjective rating system developed by Penn DOT. Both the modular expansion joints and the newer expansion dams were performing satisfactorily. Both types of joints leaked and experienced a number of minor hardware problems. Some of the joints may warrant repairs to restore their complete function. Deck drains and drain outlet piping systems were inspected. The deck drains inspected included those having square and rectangular inlets, pipe drains appear susceptible to clogging. Large scuppers performed well. Also, simple straight drop pipes were less clog prone than complex piping systems. Recommendations are provided to minimize clogging problems.