Dowel Bars

Dowel bars are short steel bars that provide a mechanical connection between slabs without restricting horizontal joint movement. They increase load transfer efficiency by allowing the leave slab to assume some of the load before the load is actually over it. This reduces joint deflection and stress in the approach and leave slabs.

Figure 1. Typical dowel bar location on transverse joints

Dowel bars are typically 32 to 38 mm (1.25 to 1.5 inches) in diameter, 460 mm (18 inches) long and spaced 305 mm (12 inches) apart. Specific locations and numbers vary by state, however a typical arrangement might look like Figure 1. In order to prevent corrosion, dowel bars are either coated with stainless steel (Figure 2) or epoxy (Figure 3). Dowel bars are usually inserted at mid-slab depth and coated with a bond-breaking substance to prevent bonding to the PCC. Thus, the dowels help transfer load but allow adjacent slabs to expand and contract independent of one another. Figure 3 shows typical dowel bar locations at a transverse construction joint.

Figure 2. Stainless steel-clad dowel bars/ (Epoxy Coating on Ends Only)

Figure 3. Dowel bars in place at a construction joint- the green color is from the epoxy coating.

Surveys

Dowel Bar Survey

Questions

  • Do you utilize epoxy coated smooth dowels in your concrete pavements?
  • Have you excavated smooth dowels from concrete pavements recently? If yes, what condition were they in generally?
  • Have you experienced rusting problems with epoxy coated smooth dowels? If yes, about how long were they in place and was the rusting cause for pavement joint failure?
  • Do you use smooth dowels that are not epoxy coated? If yes, what coatings do you use and what percentage of your smooth dowels are coated with something other than epoxy?
  • Additional comments:
  • Would you like a coy of the compiled results of this survey?

Results

Dowel Bar Survey

Epoxy Coated Dowel Bars Used in Portland Cement Concrete Pavements-Kentucky DOT

Questions

  • Do you utilize epoxy coated smooth dowels in your concrete pavements?
  • Have you excavated smooth dowels from concrete pavements recently? If yes, what condition were they in generally?
  • Have you experienced rusting problems with epoxy coated smooth dowels? If yes, about how long were they in place and was the rusting cause for pavement joint failure?
  • Do you use smooth dowels that are not epoxy coated? If yes, what coatings do you use and what percentage of your smooth dowels are coated with something other than epoxy?

Results

Epoxy Coated Dowel Bars Used in Portland Cement Concrete Pavements