AEROSPACE REPORT NO. ATR-2005(7796)-1 The Application of Qualification Testing, Field Testing, and Accelerated Testing for Estimating Long-Term Durability of Composite Materials for Caltrans Applications 25 February 2005 Prepared by G. L. STECKEL and G. F. HAWKINS Space Materials Laboratory Laboratory Operations Prepared for STATE OF CALIFORNIA DEPARTMENT OF TRANSPORTATION Sacramento, CA 94273 Contract No. 59A0188 Engineering and Technology Group EL SEGUNDO, CALIFORNIA PUBLIC RELEASE IS AUTHORIZED LABORATORY OPERATIONS The Aerospace Corporation functions as an “architect-engineer” for national security programs, specializing in advanced military space systems. The Corporation's Laboratory Operations supports the effective and timely development and operation of national security systems through scientific research and the application of advanced technology. Vital to the success of the Corporation is the technical staff’s wide-ranging expertise and its ability to stay abreast of new technological developments and program support issues associated with rapidly evolving space systems. Contributing capabilities are provided by these individual organizations: Electronics and Photonics Laboratory: Microelectronics, VLSI reliability, failure analysis, solid-state device physics, compound semiconductors, radiation effects, infrared and CCD detector devices, data storage and display technologies; lasers and electro-optics, solid-state laser design, micro-optics, optical communications, and fiber-optic sensors; atomic frequency standards, applied laser spectroscopy, laser chemistry, atmospheric propagation and beam control, LIDAR/LADAR remote sensing; solar cell and array testing and evaluation, battery electrochemistry, battery testing and evaluation. Space Materials Laboratory: Evaluation and characterizations of new materials and processing techniques: metals, alloys, ceramics, polymers, thin films, and composites; development of advanced deposition processes; nondestructive evaluation, component failure analysis and reliability; structural mechanics, fracture mechanics, and stress corrosion; analysis and evaluation of materials at cryogenic and elevated temperatures; launch vehicle fluid mechanics, heat transfer and flight dynamics; aerothermodynamics; chemical and electric propulsion; environmental chemistry; combustion processes; space environment effects on materials, hardening and vulnerability assessment; contamination, thermal and structural control; lubrication and surface phenomena. Microelectromechanical systems (MEMS) for space applications; laser micromachining; laser-surface physical and chemical interactions; micropropulsion; micro- and nanosatellite mission analysis; intelligent microinstruments for monitoring space and launch system environments. Space Science Applications Laboratory: Magnetospheric, auroral and cosmic-ray physics, wave-particle interactions, magnetospheric plasma waves; atmospheric and ionospheric physics, density and composition of the upper atmosphere, remote sensing using atmospheric radiation; solar physics, infrared astronomy, infrared signature analysis; infrared surveillance, imaging and remote sensing; multispectral and hyperspectral sensor development; data analysis and algorithm development; applications of multispectral and hyperspectral imagery to defense, civil space, commercial, and environmental missions; effects of solar activity, magnetic storms and nuclear explosions on the Earth’s atmosphere, ionosphere and magnetosphere; effects of electromagnetic and particulate radiations on space systems; space instrumentation, design, fabrication and test; environmental chemistry, trace detection; atmospheric chemical reactions, atmospheric optics, light scattering, state-specific chemical reactions, and radiative signatures of missile plumes. 1. REPORT NO. 2. GOVERNMENT ACCESSION NO. 3. RECIPIENT’S CATALOG NO. CA/ES-ATR-2005-7796-1 4. TITLE AND SUBTITLE 5. REPORT DATE The Application of Qualification Testing, Field Testing, and 25 February 2005 Accelerated Testing for Estimating Long-Term Durability of 6. PERFORMING ORGANIZATION CODE Composite Materials for Caltrans Applications 7. AUTHOR(S) 8. PERFORMING ORGANIZATION REPORT NO. G. L. Steckel and G. F. Hawkins ATR-2005(7796)-1 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. WORK UNIT NO. The Aerospace Corporation P.O. Box 92957 11. CONTRACT OR GRANT NO. Los Angeles CA 90009 59A0188 12. SPONSORING AGENCY NAME AND ADDRESS 13. TYPE OF REPORT & PERIOD COVERED State of California Final Report Department of Transportation Sacramento, CA. 94273-0001 14. 14. SPONSORING AGENCY CODE 15. SUPPLEMENTARY NOTES 16. ABSTRACT Caltrans has begun utilizing composite materials in several bridge applications. Formal procedures for the evaluation and qualification of composite casings for seismic retrofit of bridge columns were adopted in 1995 and are being applied by Caltrans to all structural applications of composite materials. Environmental durability testing to ensure the long- term integrity of composite structures is an integral part of the qualification process. The Aerospace Corporation sup- ported Caltrans in the development of qualiication requirements and test procedures, and conducted durability testing on candidate systems for the composite casings for seismic retrofit application. More recently, Caltrans contracted with Aerospace to perform qualification durability testing on composite materials used in the construction of the King’s Stormwater Bridge and to conduct research activities related to the durability of composites for infrastructure applica- tions. Research areas included a field durability study conducted at the Yolo Causeway to help define the field environ- ment, and to compare durability in the field environment with the results of the qualification test program. A short- coming of the qualification program was the inability to make long-term (30−50 yr) tensile strength projections from the relatively short-term (1.14 yr) exposure data for those systemsthat showed susceptibility in moist environments. Post- exposure tensile strength data from accelerated exposures at an elevated temperature and significantly longer term (6.3 yr) laboratory exposures under the qualification conditions were combined with the qualification test data to develop expressions for making long-term tensile strength projections under service conditions. 17. KEY WORDS 18. DISTRIBUTION STATEMENT Composites, Infrastructure, Seismic Retrofit, No Restrictions. This document is available Durability through the National Technical Information Service, Springfield, VA 22161 19. SECURITY CLASSIF. (OF THIS REPORT) 20. SECURITY CLASSIF. (OF THIS PAGE) 21. NO. OF PAGES 22. PRICE Unclassified Unclassified 89 AEROSPACE REPORT NO. ATR-2005(7796)-1 THE APPLICATION OF QUALIFICATION TESTING, FIELD TESTING, AND ACCELERATED TESTING FOR ESTIMATING LONG-TERM DURABILITY OF COMPOSITE MATERIALS FOR CALTRANS APPLICATIONS Prepared by G. L. STECKEL and G. F. HAWKINS Space Materials Laboratory Laboratory Operations 25 February 2005 Engineering and Technology Group THE AEROSPACE CORPORATION El Segundo, CA 90245-4691 Prepared for STATE OF CALIFORNIA DEPARTMENT OF TRANSPORTATION Sacramento, CA 94273 Contract No. 59A0188 PUBLIC RELEASE IS AUTHORIZED ii Abstract Caltrans has begun utilizing composite materials in several bridge applications, including girders and decks on new bridges, replacement decks and seismic retrofit of columns on old bridges, and for general structural reinforcement. Formal procedures for the evaluation and qualification of composite casings for seismic retrofit of bridge columns were adopted in 1995 and are being applied by Caltrans to all structural applications of composite materials. Environmental durability testing to ensure the long-term integrity of composite structures is an integral part of the qualification process. The Aerospace Corporation supported Caltrans in the development of quali- fication requirements and test procedures, and conducted durability testing on candi- date systems for the composite casings for seismic retrofit application. More recently, Caltrans contracted with Aerospace to perform qualification durability test- ing on composite materials used in the construction of the King’s Stormwater Bridge and to conduct research activities related to the environmental durability of compos- ites for infrastructure applications. Research areas included a field durability study conducted at the Yolo Causeway to help define the field environment through humidity, pH, and temperature sensors, and to compare durability in the field envi- ronment with the results of the qualification test program. A shortcoming of the qualification durability test program was the inability to make long-term (30−50 yr) tensile strength projections from the relatively short-term (1.14 yr) laboratory expo- sure data for those systems, chiefly E-glass-reinforced composites, that showed sus- ceptibility in moist environments. Post-exposure tensile strength data from acceler- ated exposures at an elevated temperature and significantly longer term (6.3 yr) labo- ratory exposures under the qualification conditions were combined with the qualifi- cation test data to develop expressions for making long-term tensile strength projec- tions under service conditions. iii Acknowledgments The authors wish to acknowledge the support of the following individuals: • Li-Hong Sheng (Caltrans) for program guidance throughout this effort • Ben Nelson for monitoring environmental exposures and conducting ten- sile tests and lap shear strength tests • Bruce Weiller for selection and validation of sensors for field environ- ment monitoring • Paul Chaffee for construction of waterproof sensor chambers • Ben Nelson, George Panos, and Oscar Esquivel for mounting composite panels and sensors on columns at the Yolo Causeway • Jack Shaffer for editing and preparing this report for publication iv Note  The SEH 51/Tyfo S E-glass/epoxy composite panels studied in this program were submitted in 1996 to Caltrans for evaluation under the Seismic Retrofit of Bridge Columns Program. At that time, the material was marketed by Hexcel-Fyfe under a joint venture between Hexcel Corporation and Fyfe Company. The material is  currently marketed separately by Fyfe Co. as SEH 51/Tyfo S and by Hexcel Corp. as Hex 3R Wrap 107/Hex 3R Epoxy 300. Therefore, all data in this report for SEH  51/Tyfo S also applies to Hex 3R Wrap 107/Hex 3R Epoxy 300. All trademarks, service marks, and trade names are the property of their respective owners. v Contents 1. Durability of Composites for the King’s Stormwater Bridge............................................... 1 1.1 Introduction................................................................................................................. 1 1.2 Experimental Procedures............................................................................................ 2 1.2.1 Environmental Exposures.............................................................................. 2 1.2.2 Carbon/Epoxy Girder Composite System...................................................... 5 1.2.3 E-glass/Epoxy Vinyl Ester Bridge Deck Composite System......................... 6 1.2.4 Material Property Measurements................................................................... 8 1.3 Results and Discussion for the Carbon/Epoxy Girder Composite.............................. 11 1.3.1 Physical Appearance and Optical Microscopy.............................................. 11 1.3.2 Baseline Properties from Control Panels....................................................... 12 1.3.3 Effects of Environmental Exposures on Mechanical and Physical Properties 18 1.4 Results and Discussion for the E-glass/Epoxy Vinyl Ester Deck-Reinforcement Composite and Bonded Assemblies............................................................................ 21 1.4.1 Physical Appearance and Optical Microscopy.............................................. 21 1.4.2 Baseline Properties from Control Panels....................................................... 23 1.4.3 Baseline Lap Shear Strength from Bonded Assemblies................................ 26 1.4.4 Effects of Environmental Exposures on Mechanical and Physical Properties 27 1.5 Summary and Conclusions......................................................................................... 32 2. Durability of Composites Exposed to the Yolo Causeway Environment............................. 35 2.1 Introduction................................................................................................................. 35 2.2 Materials and Field Exposure Procedures................................................................... 36 2.3 Testing Procedures...................................................................................................... 39 2.4 Results and Discussion............................................................................................... 40 2.5 Summary and Conclusions......................................................................................... 49 3. Environmental Monitoring of Composite Casings at the Yolo Causeway........................... 51 3.1 Introduction and Background..................................................................................... 51 vi 3.2 Temperature/Relative Humidity Sensors and Data Acquisition................................. 51 3.3 Sensor Mounting......................................................................................................... 52 3.4 Results and Discussion............................................................................................... 53 3.5 Summary and Conclusions......................................................................................... 59 4. Long-Term Durability of E-glass/Polymer Composites....................................................... 60 4.1 Introduction and Background..................................................................................... 61 4.2 Experimental Procedures............................................................................................ 61 4.3 Results and Discussion............................................................................................... 62 4.4 Summary and Conclusions......................................................................................... 69 References...................................................................................................................................... 70 Appendix 1—Tabulated Data for Individual Tensile, SBSS, and Hardness Measurements for the Kings Stormwater Bridge Carbon/Epoxy Girder Composite....................... 73 Appendix 2—Tabulated Data for Individual Tensile, Hardness, and Bondline LSS Measurements for the Kings Stormwater Bridge E-glass/Epoxy Vinyl Ester Deck-Reinforcement Composite.......................................................... 83 Figures 1.1. Photograph of MMC pultruded bridge deck sections........................................................ 1 1.2. Photograph of ATK flat panels and ring segments........................................................... 5 1.3. Photograph of MMC bonded assembly and LSS samples................................................ 7 1.4. Drawing for preparation of single lap shear samples from bonded composite panel assemblies.......................................................................................................................... 10 1.5. Micrograph of cross section normal to axial direction of carbon/epoxy ring segment exposed to freeze/thaw exposure................................................................. 12 1.6. Micrograph of cross section normal to fiber direction of carbon/epoxy Panel No. A03-1M after 10,000 h alkali exposure............................................................ 12 1.7. Micrograph of cross section normal to fiber direction of carbon/epoxy Panel No. A03-2M after weathering exposure.................................................................. 13 vii