LOW-SEVERITY
TRANSVERE CRACKS
If you have low-severity transverse cracks while aggregate interlock is still intact, you need to perform:
Dowel Bar Retrofit
Dowel bar retrofit (DBR) is a concrete pavement preservation (CPP) tool that restores load transfer across transverse joints and cracks by installing dowel bars to link adjoining slabs. Mechanical load transfer devices such as round steel dowel bars prevent differential vertical movement of the slabs at the joints and cracks, thereby eliminating the formation of faults or stepoffs. Used in conjunction with other CPP practices, such as diamond grinding, DBR can return a concrete roadway to a structurally sound, smooth condition that can exceed the smoothness and noise values attained at the time of construction.
To perform DBR, slots are cut using diamond saw blades. The slots are placed on 1-foot centers, centered over the transverse joint or crack and parallel to the centerline with three or four slots per wheel path. Dowel bar assemblies are placed into cleaned slots then backfilled, patched and diamond ground to provide a safe, smooth and quiet surface.
Where to consider DBR:
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Pavements that exhibit a reduction in load transfer.
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Joint and crack faulting between 1/8 to 3/4 inch.
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Transverse cracks that are reasonably tight with minimal spalling.
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Pavements that were constructed as non-doweled jointed pavements, which can have DBR applied to prevent future faulting.
If aggregate interlock is lost, refer to the cracked slab section.
Resources
Tech Brief: Proper Joint Preparation Prior to Sealing and Resealing Concrete Joints
To seal or not to seal has been a strongly debated question for more than a quarter century. This debate has continued due to the variable performance of installed sealants and the inability to relate sealant condition to pavement performance. Joint sealing has been a process in constructing concrete pavements for over a hundred years, yet the challenge of quality installation continues. With the introduction of the OSHA PM10 regulations (29 CFR 1926.1153), this challenge has become even greater with the need to ensure environmental worker safety.
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Technical
Airport/Airfield, City/Municipal, Highway
Full & Partial Depth Repair
Structural/Material Issues
Tech Brief: The Use of Vacuums to Clean Sawed Pavement Joints
Sawing joints in concrete pavements potentially exposes workers to respirable crystalline silica dust which may increase the risk of health issues. OSHA has standards designed to protect workers from these risks: respirable Crystalline Silica Standard (29 CFR 1926.1153) and Respiratory Protection Standard (29 CFR 910.134) among others. This Tech Brief is not intended to address the health risks, but instead to provide information on devices which can be used to minimize them.
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Technical
Airport/Airfield, City/Municipal, Highway
Full & Partial Depth Repair
Structural/Material Issues
Minnesota State Aid Concrete Pavement Rehabilitation Best Practices Manual
This manual has been developed, with permission, from information published by the Minnesota Department of Transportation (MnDOT) and the American Concrete Pavement Association’s Concrete Pavement Repair Manual, which was printed in May 2003. It includes joint repair, partial-depth repair (PDR), full-depth repair (FDR) and dowel bar retrofit (DBR).
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Technical Info
Bridge, City/Municipal, Highway
Concrete Pavement Preservation and Restoration
Structural/Material Issues
Dowel Bar Retrofitting in Buena Vista County, Iowa
In Buena Vista County, Iowa, a study sponsored by the Iowa Highway Research Board and Iowa Department of Transportation evaluated different dowel bar materials for local road pavements. The project, conducted by Iowa State University, included diamond grinding to improve the international roughness index and reduce faulting. The findings indicated that fiber-reinforced polymer (FRP) dowels performed better in terms of pavement smoothness compared to steel dowels.
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City/Municipal
Dowel Bar Retrofit
Structural/Material Issues
An Evaluation of Retrofit Load Transfer Materials and Dowel Bar Configurations
The Minnesota Department of Transportation (Mn/DOT) constructed experimental test sections of retrofit load transfer and DBR on U. S. Highway 52, a divided 4-lane highway near Zumbrota, Minnesota that was originally constructed in 1983. Multiple dowel bar configurations were evaluated.
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Technical Info
City/Municipal, Highway
Dowel Bar Retrofit
Structural/Material Issues
Evaluation of Dowel Bar Retrofits for Local Road Pavements
The Buena Vista County staff developed a construction project to retrofit the dowels in the joints and grind the surface of the test pavement. The contract included items for the preparation and the installation of dowels in each of the transverse joints in the pavement. After a careful analysis of the dowel bar retrofit (DBR) sections, the conclusion was made that FRP bars maintain a better IRI. However, this comes at a higher cost.
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Technical Info
City/Municipal
Dowel Bar Retrofit
Structural/Material Issues