Field Investigation of Dowel Misalignment at LTPP Sections

摘要

MIT Scan technology is a non-destructive method to measure the alignment of dowel bars placed in transverse joints of jointed plain concrete pavements (JPCP). Misalignment of dowel bars can potentially lead to reduced load transfer efficiency (LTE), cracking, spalling and faulting. Several agencies across the U.S. have adopted specifications for dowel bar misalignment, many using the joint score methodology. However, this methodology has never been validated using field studies. National Cooperative Highway Research Program (NCHRP) Report 637 provides a methodology to determine an effective dowel diameter; however, this was based on laboratory testing and limited field studies. This paper presents results of a Federal Highway Administration (FHWA) project to collect MIT Scan data on Long Term Pavement Performance (LTPP) sections. The analysis did not indicate any definitive relationship between joint score and cracking/spalling within the analysis range for most States. This is not to say that severely misaligned dowel bars do not affect pavement performance, particularly localized distresses. Analysis of effective dowel diameter as a measure of dowel misalignment for use with Pavement ME suggests that using effective dowel diameter is a less biased estimator of long-term LTE as modeled using Pavement ME than using actual dowel diameter, thus suggesting a relationship between dowel misalignment and long-term LTE. The remaining bias and scatter suggests that models (effective dowel diameter model and LTE model in Pavement ME) can be improved using the data collected as part of this study.