Project Details
RESEARCHERS
Pangil Choi, Hoonill Won, Fei Yu, Moon C. Won
KEYWORDS
Bond strength (Materials), Concrete overlays, Continuously reinforced concrete pavements (CRC pavements), Deflection tests, Finite element method, Mechanistic-empirical pavement design, Pavement maintenance, Portland cement concrete, Rehabilitation (Maintenance)
Project description
As of 2016, Texas Department of Transportation (TxDOT) managed a total of 16,327 lane miles of Portland cement concrete (PCC) pavement, which represents an important asset to TxDOT. As PCC pavements in Texas built in the 1960s through 1980s have already exceeded or are approaching the end of their design lives, many of these projects will require some form of rehabilitation. Considering the expected steady increase in truck traffic in the future, PCC overlays represent one of the best options for that rehabilitation. Currently, guidelines on PCC pavement overlays on PCC pavement focus on overlay slab thickness determination, but do not provide clear directions on (1) whether existing PCC pavement is a good candidate for concrete overlay, or (2) if the pavement is a good candidate, which overlay type—bonded concrete overlay (BCO) or unbonded concrete overlay (UBCO)—is appropriate. Sound guidelines are needed for the selection of an optimum overlay type, especially for continuously reinforced concrete pavement (CRCP) overlays, which could extend the performance period of structurally deficient PCC pavements in Texas at a reasonable cost. Three primary tasks conducted in this study were (1) the evaluations of PCC overlay performance of various BCO and UBCO projects built in Texas, (2) the development of BCO design procedures based on mechanistic-empirical principles, and (3) the development of threshold deflection values to determine whether existing pavements are good candidates for overlays. The structural behavior and performance of PCC overlays were investigated by deflection testing, bond strength testing, and material property evaluations. Three-dimensional finite element analyses were conducted to investigate structural responses of various PCC overlay systems under wheel and environmental loadings. Based on the analysis results and field performance of PCC overlays, a BCO design program was developed. For the UBCO system, detailed analyses were conducted to evaluate the soundness of the 1993 American Association of State Highway and Transportation Officials (AASHTO) design procedures. To facilitate the implementation of the research findings as well as to help TxDOT engineers select an optimum overlay type, the project team compiled the extensive information collected and made recommendations.
