J. E. Bolluyt, V. B. Kau, L. F. Greimann Performance of Strip Seals in Iowa Bridges, Pilot Study January 2001 Sponsored by the Iowa Department of Transportation and the Iowa Highway Research Board FINAL REPORT Iowa Highway Research Board Iowa Department Project TR-437 of Transportation report College of Engineering Iowa State University The opinions, findings, and conclusions expressed in this publication are those of the authors and not necessarily those of the Iowa Highway Research Board or the Iowa Department of Transportation. J. E. Bolluyt, V. B. Kau, L. F. Greimann Performance of Strip Seals in Iowa Bridges, Pilot Study Sponsored by the Iowa Department of Transportation and the Iowa Highway Research Board FINAL REPORT Iowa Highway Research Board Project TR-437 College of Engineering Iowa State University ABSTRACT A pilot study was conducted on the premature failures of neoprene strip seals in expansion joints in Iowa bridges. In a relatively large number of bridges, strip seals have pulled out of the steel extrusions or otherwise failed well before the expected life span of the seal. The most serious consequence of a strip-seal failure is damage to the bridge substructure due to salt, water, and debris interacting with the substructure. A literature review was performed. Manufacturers’ specifications and recommendations, practices in the states bordering Iowa, and Iowa DOT design and installation guidelines were reviewed. Discussions were held with bridge contractors and the installation of a strip seal system was observed. Iowa DOT bridge databases were analyzed. A national survey was conducted on the use and performance of strip seals. With guidance from the Iowa DOT, twelve in-service bridges with strip-seal expansion joints were selected for detailed investigation. Effective bridge temperatures and corresponding expansion-joint openings were measured, DOT inspection reports were reviewed, and likely cause(s) of premature failures of strip seals were proposed. All of the seals used in the twelve bridges that had the most serious failures were in concrete girder bridges. Experimental results show that for a majority of these serious failures, the joint opening at 0° F predicted by the Iowa DOT design equations, the joint opening at 0° F extrapolated from the experimental data, or both, are larger than the movement rating of the strip seal specified on the bridge plans. Other likely causes of premature failures of seals in the twelve bridges include debris and ice in the seal cavity, a large skew and the corresponding decrease in the movement rating of the seal, improper installation, and improper setting of the initial gap. v TABLE OF CONTENTS Page 1. INTRODUCTION ............................................................................................................1 1.1. Background 1 1.2. Objectives 2 1.3. Overview and 2 2. LITERATURE REVIEW .................................................................................................5 2.1. Coefficients of Expansion and Contraction (a values) 5 2.1.1. Concrete 5 2.1.2. Steel 11 2.2. Effective Bridge Temperature 12 2.3. Movement Characteristics 15 2.4. Creep and Shrinkage of Concrete 17 2.4.1. Creep 17 2.4.2. Shrinkage 20 2.5. Vertical Wheel Loading on Expansion Joints 23 2.6. Miscellaneous Topics 25 2.6.1. Drainage of Expansion Joints 25 2.6.2. Field Evaluations and General Recommendations 26 3. DESIGN OF STRIP SEAL EXPANSION JOINT SYSTEMS ......................................29 3.1. Manufacturers’ Recommendations 29 3.1.1. Manufacturers’ Recommendations Related to Design 30 3.1.2. Manufacturers’ Recommendations Related to Materials 30 3.2. Practices in States Bordering Iowa 32 3.2.1. Design Considerations and Requirements in Neighboring States 33 3.2.2. Material Requirements in Neighboring States 37 3.3. Design Practices in Iowa 41 3.4. Review of Iowa DOT Design Guidelines for Strip Seal Systems 43 vi 4. FABRICATION AND INSTALLATION OF STRIP SEAL SYSTEMS......................51 4.1. Manufacturers’ Recommendations 51 4.1.1. Manufacturers’ Recommendations for Fabrication 51 4.1.2. Manufacturers’ Recommendations for Installation 52 4.2. Practices in States Bordering Iowa 57 4.3. Fabrication and Installation Practices in Iowa 57 5. DATABASE ANALYSIS AND SURVEY OF STATE DOTS .....................................49 5.1. Overview 79 5.2. Analysis Based on Iowa DOT Databases 79 5.3. Survey of State Departments of Transportation 84 6. EXPERIMENTAL INVESTIGATION OF SELECTED BRIDGES .............................91 6.1. Overview 91 6.2. Experimental Program 91 6.2.1. Bridge Selection 91 6.2.2. Instrumentation 93 6.2.3. Data Collection 96 6.3. Experimental Results 98 6.3.1. Bridge 1: 0781.1R218 (FHWA 606200) 99 6.3.2. Bridge 2: 0781.1L218 (FHWA 606210) 106 6.3.3. Bridge 3: 0996.0R218 (FHWA 601235) 110 6.3.4. Bridge 4: 0996.0L218 (FHWA 601240) 115 6.3.5. Bridge 5: 0787.7A218 (FHWA 601575) 120 6.3.6. Bridge 6: 0784.8S218 (FHWA 605800) 125 6.3.7. Bridge 7: 8561.5L030 (FHWA 607795) 130 6.3.8. Bridge 8: 7776.8L065 (FHWA 606800) 133 6.3.9. Bridge 9: 6485.3L030 (FHWA 601620) 136 6.3.10. Bridge 10: 6402.0S014 (FHWA 007911) 140 6.3.11. Bridge 11: 6403.6L014 (FHWA 035431) 145 6.3.12. Bridge 12: 6481.9L030 (FHWA 601895) 150 vii 6.4. Summary of the Experimental Results 153 6.4.1. Experimental a-Values Versus Design a-Values 153 6.4.2. Apparent Causes of Poor Strip Seal Performance 155 7. RECOMMENDATIONS..............................................................................................159 7.1. Recommendations for Design, Installation, and Maintenance Procedures 159 7.1.1. Bridge Temperature Ranges for Design 159 7.1.2. Bridge Temperature for Setting the Gaps 159 7.1.3. Selection of Strip Seal Size and Specifications for Gap Settings 160 7.1.4. End Detail 161 7.1.5. Leak Test After the Installation Process 162 7.1.6. Specifications for the Design and Installation of Strip Seal Systems 162 7.1.7. Cleaning of Expansion Joints 163 7.2. Related Recommendations 164 7.2.1. Inclusion of Additional Information in Iowa DOT Databases 164 7.2.2. Further Research 164 8. SUMMARY AND CONCLUSION .............................................................................169 8.1. Summary 169 8.2. Conclusions 170 9. ACKNOWLEDGEMENTS ...........................................................................................173 10. REFERENCES .............................................................................................................175 APPENDIX A: THERMOCOUPLE LOCATION TEST DATA.....................................179 1. INTRODUCTION 1.1 Background Expansion joints are used in bridges to allow expansion and contraction of the bridge superstructure due to temperature changes. In order to prevent salt, water and debris from passing through the expansion joint opening and reaching the bridge substructure, a seal or trough is required in the expansion joint opening. A strip-seal expansion joint device is one alternative for this function. It consists of a pair of steel retainer rails (steel extrusions), a polychloroprene (neoprene) gland and lubricant/adhesive material to facilitate the installation of the gland and to seal the gland in the extrusions. Steel extrusions Backwall Elastomeric strip seal Bridge deck Expansion joint opening Figure 1.1 Typical strip-seal expansion joint device 2 According to a manufacturer’s representative, the expected service life of a strip seal (neoprene gland) is fifteen to twenty years. In Iowa however, a significant number of strip seals have failed prematurely, which for purposes of this report will mean failure in less than five years. In these premature failures, the strip seal either tears or pulls out from the extrusions relatively soon after the bridge construction is completed. The most serious consequence of a strip-seal failure is damage to the bridge substructure due to salt, water and debris interacting with the substructure, which can result in large costs to repair or replace portions of the damaged bridge. 1.2 Objectives A number of possible causes for premature strip-seal failures have been proposed including thermal movement different than that predicted, incorrect setting of the expansion joint opening during construction, and wheel loads transmitted to the seal by debris and ice in the joint. The main objective of this research project was to investigate these and other possible causes of the premature failures of strip seals in Iowa bridges. 1.3 Overview and Scope To accomplish the research objective, existing information was assembled and analyzed and detailed investigations of the strip-seal expansion joints on twelve Iowa bridges were carried out. A number of tasks were performed as part of this investigative process. A comprehensive literature search was conducted. Sources listed by the Transportation Research Information Services (TRIS) were obtained. International literature 3 and sources not covered by TRIS were sought by using TRANSPORT, the CD-ROM database available from Transportation Research Information. Service [1]. Design criteria, recommended installation procedures, sample specifications, and supporting test data were obtained from various manufacturers of strip-seal expansion joint systems. A national survey of state departments of transportation (DOTs) was conducted to obtain information about the use and performance of strip-seal expansion joint systems outside of Iowa. Design and installation practices and specifications used in states surrounding Iowa were obtained. Databases maintained by the