Design and Short-Term Performance of Continuously Reinforced Concrete Pavements Using Glass Fiber Reinforced Polymer Rebars

Student
Choi, Jeong-Hoon

Advising Faculty
Roger H. L. Chen, Ph.D., Chair
Hota V. GangaRao, Ph.D.
Eric Johnson, Ph.D.
Bruce. S. J. Kang, Ph.D.
Syd Peng, Ph.D.

Abstract
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). Preliminary studies were conducted in regard to the effect of using GFRP rebars as reinforcement in CRCP on the concrete stress development, which is directly related to the concrete crack formation that is inevitable in CRCP. Under restrained conditions, concrete volume change due to shrinkage and temperature variations is known to cause early-age cracks in CRCP. In this study, an analytical model was 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 showed that the stress level in concrete was reduced with GFRP rebars due to low Young’s modulus of GFRP. In addition, the analytical model was utilized to estimate the concrete strain variation in reinforced concrete slabs due to changes in the concrete volume, and the results were compared with the experimental observation. Finite Element (FE) methods were 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 was proposed. Among them, #7 GFRP-rebars at 6 in. (15.24 cm) spacing (reinforcing ratio of 1.00%) was shown to be economically suitable for the longitudinal reinforcement design of the GFRP-CRCP to be constructed on Route 9 near Martinsburg, WV on September 25th, 2007. WVDOT allocated a 2,000-foot (610-meter)-long, two-lane section on Route 9 as the testing ground for the study. The experimental design incorporated two CRCP sections, GFRP-CRCP and steel-CRCP sections, for comparison; the steel-CRCP was designed with #6 steel rebars at 6 in. (15.24 cm) spacing. The GFRP- and the steel-reinforced segments were both 1,000 ft (305 m) long and 10 in. (25 cm) thick. It was specified that both segments were to be constructed of concrete containing limestone coarse aggregate placed on a cement-stabilized subbase. From the field study, it was found that the performance of GFRP-CRCP was satisfactory during the first 4 months, particularly because the observed maximum value of crack width, 0.034 in. (0.864 mm), met the AASHTO limiting criterion for crack width—ÿ0.04 in. (1 mm)—which is of utmost importance in providing adequate aggregate interlock and ensuring the integrity of the pavement.