Evaluation of joint activation and joint spacing in concrete overlays

Abstract

Optimized joint spacing is crucial to ensure concrete overlay performance and service life. While pavement joints are used to control cracks in concrete slabs and help relieve stresses, not all sawn joints crack or “activate” initially. If cracks do not form below saw-cut joints, the effective slab length is high, potentially leading to excessive movements at the activated joints and increasing the risk of random cracking. Non-destructive testing (NDT) approaches, such as MIRA, are proved to be effective on detecting whether a saw-cut has been activated. The saw-cutting joints from 54 concrete overlay project sites in Iowa were evaluated using a MIRA.  The data indicated that approximately 60% to 70% of joints assessed were activated for the shorter joint spacing, while more than 95% of joints were activated for conventional joint spacing. These results were used to develop recommendations with respect to optimized joint spacing of concrete overlays. .

KEYWORDS:

• Concrete overlays
• non-destructive testing (NDT)
• ultrasonic low-frequency tomography (MIRA)
• joint spacing
• joint activation

Acknowledgements

The authors would like to thank the Iowa Department of Transportation (DOT) for sponsoring this research. The project’s Technical Advisory Committee (TAC) members Chris Brakke, Eric Cowles, Todd Hanson, Kevin Jones, Michael Kennerly, Kevin Merryman, and Scott Schram from Iowa DOT are gratefully acknowledged for their guidance. The authors also would like to thank Snyder and Associates, including Dale Harrington, Melisse Leopold, and Jerod Gross; the National Concrete Pavement Technology Center (CP Tech Center) staff at Iowa State University (ISU), including Tom Cackler, Gordon L. Smith, Steven Tritsch, and the staff at University of Illinois Urbana-Champaign (UIUC), including Jeffery R. Roesler and Quang Tran for their full support in this study. The authors would also like to thank the Iowa Concrete Paving Association (ICPA) staff, including John Cunningham, and Daniel E. King, for their assistance with the data collection. The authors gratefully acknowledge the partial financial support provided by the National Natural Science Foundation Project (NSFC 51868066, 52178185); Opening Foundation of Research and Development Center of Transport Industry of Technologies, Materials and Equipments of Highway Construction and Maintenance. (Gansu Road & Bridge Construction Group GLKF201807) and the Science and Technology Projects of Gansu Transportation Department (2019-17).The contents of this paper reflect the views of the authors who are responsible for the facts and accuracy of the data presented within. The contents do not necessarily reflect the official views and policies of the Iowa DOT. This paper does not constitute a standard, specification, or regulation.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

The authors gratefully acknowledge the partial financial support provided by the Iowa Department of Transportation (TR-698); National Natural Science Foundation Project (NSFC 51868066 52178185); Opening Foundation of Research and Development Center of Transport Industry of Technologies Materials and Equipments of Highway Construction and Maintenance. (Gansu Road & Bridge Construction Group GLKF201807) and the Science and Technology Projects of Gansu Transportation Department (2019–17).