Dowel Bar Retrofits Mark 20th Anniversary in U.S.

Pavement Preservation Journal, Winter 2011, Vol. 5, No. 2

As the issue of infrastructure repair continues to be an ever present concern for municipalities, one repair method — dowel bar retrofit (DBR) — observed its 20th anniversary in the United States this year.

This method of retrofitting load transfer devices across transverse joints and cracks in concrete pavement has been used successfully on thousands of lane-miles in the United States, with more than six million dowel bars installed during the past 20 years.

“We are excited to see that after 20 years, DBR is being used by even more municipalities as an environmentally
friendly, economic, long term repair,” said John Roberts, executive director of the International Grooving & Grinding Association (IGGA). “This technique has spread throughout the U.S. and Canada as a viable means of preserving concrete roadways.”

DBR is a concrete pavement restoration technique that restores load transfer capability of existing jointed concrete pavement by the placement of dowel bars across joints and cracks that exhibit poor load transfer. The retrofit dowel bars ensure that the traffic load is shared, preventing differential vertical movement of the slabs at the joints and cracks, thereby eliminating the formation of faults or step-offs. It is these faults that cause the rough ride and wheel slap that is sensed when traveling on a concrete roadway that has lost its ability to transfer load from one panel to the next.

Numerous states have successfully used DBR to address faulting in older jointed plain concrete pavements. The proper approach is to saw cut and jackhammer out the slots for the dowels. Following dowel placement, the slots are then typically backfilled with a non-shrink concrete grout and the pavement is diamond-ground to restore smoothness.

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