CTRE is an Iowa State University center, administered by the Institute for Transportation.

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Phone: 515-294-8103
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Website: www.ctre.iastate.edu/

Iowa State University--Becoming the Best

Prevention of Longitudinal Cracking in Iowa Widened Concrete Pavement


Principal investigators:

Co-principal investigators:

Project status

In progress

Start date: 01/01/16
End date: 06/30/18



About the research


Over the past 10 to 15 years, Iowa has used widened concrete slabs (as opposed to the standard 12 ft concrete slab) in jointed plain concrete pavement (JPCP) design and construction. The extension of the additional 2 to 3 ft slab paved beyond the normal traffic path is intended to reduce stresses and deflections at the critical concrete pavement edge location by effectively moving the normal traffic path well away from the edge. Other advantages in using widened slab include reduced shoulder maintenance costs and increased safety of maintenance crew by minimizing their exposure in high-volume roadways.

Many widened concrete pavements in Iowa are approaching 20 years of service life. And some 14 ft widened concrete pavements are experiencing sudden occurrence of a significant amount of longitudinal cracking within 2 to 3 ft away from the edge. This distress pattern has never been reported before in Iowa and an investigative study is warranted for understanding the causes of this distress pattern.

The Wisconsin Highway Research Program (WHRP) recently published a research project report to evaluate and statistically compare the performance of concrete pavements with wider panels (14 ft wide or greater) to the performance of concrete pavements with standard width panels (12 to 13 ft) in Wisconsin. However, there does not appear to be a lot of research focusing on the design and construction of widened JPCP to prevent and minimize longitudinal cracking before it happens.

The primary objectives of this research are to identify the causes of longitudinal cracking in Iowa widened JPCP and to develop recommendations for widened JPCP design features and construction practices to prevent and minimize longitudinal cracking. Such important outcomes will enable not only the Iowa Department of Transportation (DOT) but also county and city engineers to have justification for achieving long-lasting concrete pavement in Iowa.