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.
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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.
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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.
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If aggregate interlock is lost, refer to the cracked slab section.
Resources
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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Technical Info
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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City/Municipal, Highway
Dowel Bar Retrofit
Structural/Material Issues
Concrete Repair Best Practices
Concrete pavement restoration (CPR) techniques have gained greater national significance as DOT agencies attempt to further extend infrastructure service lives prior to required major rehabilitation or reconstruction. This report consolidates best practice case studies for six CPR techniques: cross stitching, dowel bar retrofit, diamond grinding, full depth repair, partial depth repair and slab stabilization.
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City/Municipal, Highway
Concrete Pavement Preservation and Restoration, Diamond Grinding, Dowel Bar Retrofit, Full & Partial Depth Repair, Joint and Crack Resealing
Structural/Material Issues
Dowel Bar Retrofit - Do's and Don'ts
Detailed guidelines for the construction and inspection of dowel bar retrofit (DBR) projects are provided in this Washington State Department of Transportation (WSDOT) report. Essential steps include cutting slots, removing existing concrete, cleaning slots, applying silicone sealant, placing dowel bars, and patching with concrete material. The study emphasizes the importance of proper dowel bar placement tolerances and the use of diamond grinding to restore pavement smoothness. Additionally, managing slurry is highlighted to ensure environmental compliance.
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Resource Techniques:
Resource Issues:
Technical Info
City/Municipal, Highway
Dowel Bar Retrofit
Structural/Material Issues