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Project Details

Title:Tolerances for Placement of Tie Bars in Portland Cement Concrete Pavements
Principal Investigators:Nadim Wehbe
University:South Dakota State University
Status:Completed
Year:2013
Grant #:DTRT12-G-UTC08 (SAFETEA-LU Extension)
Project #:MPC-440
RiP #:01497112
RH Display ID:13590
Keywords:concrete pavements, ground penetrating radar, longitudinal joints, Portland cement concrete, service life, tie bars
 

Abstract

Tie bars provide load transfer along longitudinal joints and prevent lane separation in jointed concrete pavements. Tie bars are normally located within the middle third of the pavement thickness and span the longitudinal joint of two slabs. Tie bars are placed by staking or by using tie bar baskets prior to the placement of the concrete or during paving via automatic inserters. Inspection of South Dakota pavements after construction using ground penetrating radar (GPR) has revealed that many bars were misaligned or missing. More bars were reported missing or misaligned when automatic inserters were used. Many states, including South Dakota, have banned the use of automatic inserters based on a lack of confidence regarding the placement of tie bars. The long-term effect on the pavement from misaligned or missing bars is unknown, but it can be assumed that additional maintenance costs and reduced pavement life are both possible.

Developing an understanding of misplaced tie bars and placement tolerances is important to the South Dakota Department of Transportation (SDDOT). The financial impacts of misplaced tie bars are unknown. Misplaced tie bars could be costing the department substantial amounts of money in the long-run if undetected or uncorrected during construction.

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NDSU Dept 2880P.O. Box 6050Fargo, ND 58108-6050
(701)231-7767ndsu.ugpti@ndsu.edu