Design of Continuously Reinforced Concrete Pavements Using Glass Fiber Reinforced Polymer Rebars, FHWA-HRT-05-081 - PCCP - Pavements

Design of Continuously Reinforced Concrete Pavements Using Glass Fiber Reinforced Polymer Rebars

Publication No. FHWA-HRT-05-081 October 2005

FOREWORD

This report, Design of Continuously Reinforced Concrete Pavements Using Glass Fiber Reinforced Polymer Rebars, investigates the effects on stress development in pavement and on critical design factors from substituting glass fiber reinforced polymer (GFRP) reinforcement for conventional steel reinforcement in continuously reinforced concrete pavements (CRCPs) in order to determine the performance characteristics of the GFRP-reinforced concrete pavements. The results of this study target the design of CRCPs with GFRP rebars as an applicable reinforcement and the proposal of feasible GFRP-CRCP designs to be constructed.

This report will be useful to those interested in the effect of GFRP reinforcing rebars on shrinkage and thermal stresses in concrete as studied using analytical and numerical methods as well as experimental measurements. This study proposes a series of designs for the GFRP-reinforced CRCP based on the numerical and mechanistic results, and reveals areas recommended for further investigation.

Gary L. Henderson
Director, Office of nfrastructure Research and Development

Notice

This document is disseminated under the sponsorship of the U.S. Department of Transportation and the State of West Virginia in the interest of information exchange. The U.S. Government and the State of West Virginia assume no liability for the use of the information contained in this document. This report does not constitute a standard, specification, or regulation.

The U.S. Government and the State of West Virginia do not endorse products or manufacturers. Trademarks or manufacturers' names appear in this report only because they are considered essential to the objective of the document.

Quality Assurance Statement

The Federal Highway Administration (FHWA) provides high-quality information to serve Government, industry, and the public in a manner that promotes public understanding. Standards and policies are used to ensure and maximize the quality, objectivity, utility, and integrity of its information. FHWA periodically reviews quality issues and adjusts its programs and processes to ensure continuous quality improvement.

1. Report No FHWA-HRT-05-081		2. Government Accession No. N/A	3. Recipient's Catalog No. N/A
4. Title and Subtitle Design of Continuously Reinforced Concrete Pavements Using Glass Fiber Reinforced Polymer Rebars			5. Report Date Oct. 2005
			6. Performing Organization Code N/A
7. Authors(s) Jeong-Hoon Choi and Roger H. L. Chen, Ph.D.			8. Performing Organization Report No. N/A
9. Performing Organization Name and Address Department of Civil and Environmental Engineering West Virginia University Morgantown, WV 26506			10. Work Unit No. (TRAIS) N/A
			11. Contract or Grant No. DTFH61-99-X-00078
			13. Type of Report and Period Covered
12. Sponsoring Agency Name and Address Office of Research and Technology Services Federal Highway Administration 6300 Georgetown Pike McLean, VA 22101			14. Sponsoring Agency Code
15. Supplementary Notes The Contracting Officer's Technical Representative on this contract was Peter Kopac, Pavement Materials and Construction Team.
16. Abstract This is Task 3: Continuously Reinforced Concrete Pavement. The corrosion resistance characteristics of glass fiber reinforced polymer (GFRP) rebars make them a promising substitute for conventional steel reinforcing rebars in continuously reinforced concrete pavements (CRCPs). Studies are conducted on the effect of using GFRP rebars as reinforcement in CRCP on concrete stress development, which is directly related to the concrete crack formation that is inevitable in CRCP. Under restrained conditions, concrete volume change because of shrinkage and temperature variations is known to cause early-age cracks in CRCP. In this study, an analytical model has been developed to simulate the shrinkage and thermal stress distributions in concrete due to the restraint provided by GFRP rebars in comparison with the stresses induced by steel rebars. The results show that the stress level in concrete is reduced with GFRP rebars because of a low Young's modulus of GFRP. In addition, the analytical model has been used to estimate concrete strain variation in reinforced concrete slabs because of changes in concrete volume, and the results were compared with the experimental observation. Finite element (FE) methods are also developed to predict the stress distribution and crack width in the GFRP-reinforced CRCP section that is subjected to the concrete volume changes under various CRCP design considerations, such as the coefficient of thermal expansion (CTE) of concrete, the friction from the pavement's subbase, and the bond-slip between concrete and reinforcement. Based on the results from the FE simulation along with the mechanistic analysis, a series of feasible designs of the GFRP-reinforced CRCP is proposed. The stress levels in the GFRP reinforcement, the crack widths, and the crack spacings of the proposed pavements are shown to be within the allowable design requirements.
17. Key Words GLASS FIBER REINFORCED POLYMER, CONTINUOUSLY REINFORCED CONCRETE PAVEMENTS, REBARS, CONCRETE STRESS		18. Distribution Statement No restrictions. This document is available to the Public through the National Technical Information Service; Springfield, VA 22161
19. Security Classif. (of this report) Unclassified	20. Security Classif. (of this page)	21. No. of Pages 79	22. Price N/A

Form DOT F 1700.7 (8-72) Reproduction of completed page authorized (art. 5/94)

SI* (Modern Metric) Conversion Factors

LIST OF FIGURES

Figure 1. Photo. Typical example of reinforcement layout for CRCP (constructed on S.R. 288 in Virginia)
Figure 2. Equation. A_s
Figure 3. Equation. A_f,sh
Figure 4. Equation. R
Figure 5. Drawing. Schematic details of representative reinforced concrete prism
Figure 6. Drawing. Schematic details of equivalent cylinder used in analyses
Figure 7. Equation. dP/dx
Figure 8. Equation. τ(r)
Figure 9. Equation. (u-v) in the form of integrating γ(r)
Figure 10. Equation. (u-v) in the solved form
Figure 11. Equation. C_o
Figure 12. Equation. d²P/dx²
Figure 13. Equation. ε_c,s(t)
Figure 14. Equation. ε_c,t
Figure 15. Equation. ε_r,s
Figure 16. Equation. ε_r,t
Figure 17. Equation. (σ_c,s)_avg
Figure 18. Equation. (σ_c,t)_avg
Figure 19. Equation. β
Figure 20. Equation. E_c(t)
Figure 21. Equation. E_c
Figure 22. Graph. Maximum average tensile stress in concrete versus time (ρ = 0.00519 and L = 1.524 m (60 inches))
Figure 23. Graph. Maximum average tensile stress in concrete versus time (L = 1.524 m (60 inches)) and different GFRP reinforcing ratios, ρ)
Figure 24. Graph. Maximum average tensile stress in concrete versus time (ρ = 0.00519 GFRP and different slab lengths, L)
Figure 25. Graph. Maximum average axial stress in concrete versus temperature change (ρ = 0.00519 and L = 1.524 m (60 inches))
Figure 26. Graph. Maximum average axial stress in concrete versus temperature change(ρ= 0.00519 and L = 1.524 m (60 inches))
Figure 27. Graph. Axial stress in concrete versus longitudinal location (comparison between analytical and FEM results)
Figure 28. Equation. (ε_c)_gage
Figure 29. Equation. (ε_c,s)_gage
Figure 30. Equation. (ε_c,t)_gage
Figure 31. Photo. Number 4 steel rebar specimen for CTE measurement
Figure 32. Photo. Number 4 GFRP rebar specimen for CTE measurement
Figure 33. Photo. Titanium silicate strip specimen for CTE measurement
Figure 34. Equation. α_T/M - α_R/M
Figure 35. Equation. α_T/MΔT
Figure 36. Graph. Coefficient of thermal expansion versus temperature for reinforcing rebars from third measurement
Figure 37. Drawing. Schematic details of concrete slabs used in experiment
Figure 38. Photo. Concrete slab molds before concrete cast
Figure 39. Photo. Concrete slabs attached with strain gages
Figure 40. Graph. Axial concrete strain at midspan versus temperature change from analytical calculation
Figure 41. Graph. Axial concrete strain at midspan versus temperature change for plain concrete slab (reference temperature, T_o = about 42.39 °C (108.3 °F))
Figure 42. Graph. Axial concrete strain at midspan versus temperature change for steel-reinforced concrete slab (reference temperature, T_o = about 42.39 °C (108.3 °F))
Figure 43. Graph. Axial concrete strain at midspan versus temperature change for GFRP-reinforced concrete slab (reference temperature, T_o = about 42.39 °C (108.3 °F))
Figure 44. Drawing. Schematic details of a 2-D CRCP finite element model.
Figure 45. Graph. Axial tensile stress on concrete surface versus longitudinal location of a 1.524-m (5-ft) CRCP segment with ρ = 0.00739 and α_c = 10.26 με/°C (5.7 με/°F).
Figure 46. Graph. Axial tensile stress on concrete surface versus longitudinal location of a 1.524-m (5-ft) CRCP segment with ρ = 0.00739 and α_c = 14.40 με/°C (8.0 με/°F).
Figure 47. Graph. Axial stress in reinforcement versus longitudinal location of a 1.524-m (5-ft) CRCP segment with ρ = 0.00739 and α_c = 10.26 με/°C (5.7 με/°F).
Figure 48. Graph. Axial stress in reinforcement versus longitudinal location of a 1.524-m (5-ft) CRCP segment with ρ = 0.00739 and α_c = 14.40 με/°C (8.0 με/°F).
Figure 49. Graph. Axial stress at concrete bottom surface versus longitudinal location for two different subbase bond stiffnesses (ρ = 0.00739 and L = 1.524 m (60 inches)).
Figure 50. Graph. Axial stress at concrete top surface versus longitudinal location for two different subbase bond stiffnesses (ρ = 0.00739 and L = 1.524 m (60 inches)).
Figure 51. Image. Axial stress in concrete versus longitudinal location of a 1.524-m (5-ft) CRCP segment with ρ = 0.00739, α_c = 10.26 με/°C (5.7 με/°F), and a subbase bond-slip stiffness of 0.236 MN/m (1,350 lbf/inch).
Figure 52. Image. Axial stress in concrete versus longitudinal location of a 1.524-m (5-ft) CRCP segment with ρ = 0.00739, α_c = 10.26 με/°C (5.7 με/°F), and a subbase bond-slip stiffness of 24.271 MN/m (138,600 lbf/inch)
Figure 53. Graph. Axial stress in GFRP rebar versus longitudinal location for two different subbase bond stiffnesses (ρ = 0.00739 and L = 1.524 m (60 inches))
Figure 54. Graph. Pavement depth versus crack width for two different subbase bond stiffnesses (ρ = 0.00739 and L = 1.524 m (60 inches))
Figure 55. Graph. Axial tensile stress on concrete surface versus longitudinal location for different bond-stiffnesses (ρ = 0.00739 and L = 1.524 m (60 inches))
Figure 56. Graph. Axial stress in GFRP rebar versus longitudinal location for different bond-stiffnesses (ρ = 0.00739 and L = 1.524 m (60 inches))
Figure 57. Graph. Pavement depth versus crack width for different bond stiffnesses (ρ = 0.00739 and L = 1.524 m (60 inches))
Figure 58. Image. Axial stress in concrete versus longitudinal location of a 1.524-m (60-inch) CRCP segment with ρ = 0.00739, α_c = 10.26 με/°C (5.7 με/°F), and a subbase bond-slip stiffness of 236.409 kN/m (1,350 lbf/inch; bond-break considered)
Figure 59. Graph. Axial tensile stress on concrete surface versus longitudinal location for different slab segment lengths (ρ = 0.00739; bond-slip stiffness = 0.433 10⁹ N/m (2.474 × 10⁶ lbf/inch))
Figure 60. Graph. Axial stress in GFRP rebar versus longitudinal location for different slab segment lengths (ρ = 0.00739; bond-slip stiffness = 0.433 x 109 N/m (2.474 x 106 lbf/inch))
Figure 61. Graph. Pavement depth versus crack width for different slab-segment lengths (ρ = 0.00739; bond-slip stiffness = 0.433 × 10⁹ N/m (2.474 × 10⁶ lbf/in)).
Figure 62. Graph. Mean crack spacing versus type of coarse aggregate in concrete mix (ρ= 0.0074; asphalt-stabilized subbase).
Figure 63. Graph. Crack width versus type of coarse aggregate in concrete mix (ρ = 0.0074; asphalt-stabilized subbase).
Figure 64. Graph. Tensile stress in reinforcement at crack versus type of coarse aggregate in concrete mix (ρ = 0.0074; asphalt-stabilized subbase).
Figure 65. Graph. Mean crack spacing and crack width versus bond-slip stiffness/unit area (ρ = 0.0074; granite aggregate concrete).
Figure 66. Graph. Tensile stress in GFRP reinforcement at crack versus bond-slip stiffness/unit area (ρ = 0.0074; granite aggregate concrete).

LIST OF TABLES

Table 1. Model parameters and material properties used in analytical approximation.
Table 2. Thermal outputs and CTEs of steel and GFRP rebars at different temperature levels (from third measurement).
Table 3. Thermal outputs of slabs at different temperature levels (TS: titanium silicate; PS: plain slab; S-RS: steel-reinforced slab; G-RS: GFRP-reinforced slab).
Table 4. Model parameters and material properties used in FE study.
Table 5. Design parameters and material properties used in mechanistic analysis.
Table 6. Concrete material properties at 28 d used in mechanistic analysis (varied by using different types of coarse aggregate).
Table 7. Mechanistic prediction of crack development and reinforcement tensile stress at crack for GFRP-CRCP (varied with different types of subbase).

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