3BackgroundWisconsin DOT initiative in the early 1990s to construct widened concrete pavement, ft.Limit pavement edge stress and deflection impactsReduce shoulder maintenance costMinimize exposure of maintenance crew to high volume roadways
4Background Current problems with widened PCC: Observing Longitudinal CrackingLacking information as to why
5Objectives Understand causes of longitudinal cracking Survey six states in MidwestInput for developing guidelines
6Guidelines Development Framework Panel Width GuidelinesACPA Professionals online discussion on JPCPLiterature Review & SynthesisIn-service Performance of Wisconsin JPCPLife Cycle Cost AnalysisSurvey of Midwest Pavement Professionals
7On-line Survey522 county engineers and pavement professionals from Iowa, Minnesota, Wisconsin, Illinois, Ohio, and MichiganFall 2011Questions centered on:Criteria for determining panel widths on rural hwysCommonly used panel widthsFrequency of longitudinal cracking occurrenceProbable causes of longitudinal cracking- Design features, construction practicessuch as thickness, tie bars, etc.
8On-line Survey 37 of 522 engineers responded with information 4-month open period, Aug-Nov 2011Significant majority did not have PCC pavement in their countySample considered unbiased
9Cross-SectionWhat are selection criteria & most common panel widths?
10Criteria for Cross-Section Other: 3/4 had no concrete pavements under their jurisdictions; 1/4 use state roads "standards"
17So far….. Panel width selection factors Pavement thickness. Width-to-Thickness ratio.Traffic volumePercent trucksEase of constructionConstruction and maintenance costMost commonly used panel widths12 ft and 15 ft for 2-lane 2-way rural pavements12 ft for multi-lane rural pavements
31Methods for Fixing Long. Crack. Rout and sealCross-stitchingPartial or full panel replacement
32Cost to Repair Long. Crack. Low-end crack fill or rout-and-seal$0.50/lf to $9/lf, avg $1.20/lfHigh-end stitch or full-depth$15/lf to $300/lf, avg $122/lf
33Summary37 of 522 county engineers and pavement professionals from Iowa, Minnesota, Wisconsin, Illinois, Ohio, and MichiganAug-Nov 2011Significant majority did not have PCC pavement in their countySample considered unbiased
34Summary Factor Finding Panel Width 12 ft and 15 ft wide panels had higher longitudinal cracking frequencies than 13 ft and 14 ft wide panels.Pavement ThicknessThicker pavements (≥ 11 in) less cracking compared to thinner pavements.Trans. Joint SpacingMore longitudinal cracking tends to occur with shorter joint spacing, 20 ft spacing.Tie BarsSplit opinion whether there is an effect on longitudinal cracking.Construction-related PracticesHigh frequencies with inadequate base compaction and poor joint saw-cut timing. Misaligned dowel bars and faulty vibrators also contributing factors.Panel LocationMore cracking at mid-panel compared to the vicinity of sawn longitudinal joints.Topography and StructuresCut/Fills, highway structures (bridges, drainage, culverts) and areas with differential subgrade heaving.
35More Information wisdotresearch.wi.gov Longitudinal Cracking on Widened Pavements