Dowel Bar Retrofit - Dowel Bar Retrofit Process

Dowel Bar Retrofit Process

For dowel bar retrofit, dowels, bond breaker, expansion caps, dowel bar support chairs, foam core insert, caulking filler, non-shrink concrete backfill material and submittals are needed. The dowels need to be smooth, round, epoxy and made of bond breaker coated steel conforming to requirements. The bond breaker is to be applied on all surfaces of the dowel bar. The expansion caps belong at each end of the dowel bar and the dowel bar support chairs are used to firmly hold the dowels centered in the slots during backfill operations. The foam core insert is used to re-establish the joint or crack, which allows the bar within each side of the slot to expand and contract. The caulking filler is used to prevent backfill material from flowing into the joint or crack. Non-shrink concrete backfill material that is tested as rapid set concrete patching materials is recommended for use on DBR projects.

First, make two saw cuts in the pavement to outline the longitudinal sides of each dowel bar slot. Saw to a depth and length that allows the center of the dowel to be placed at mid-depth in the pavement slab. Saw slots parallel to each other and to the centerline of the roadway with a maximum tolerance of 1⁄4-inch per 12 inches of dowel bar length. Employ saws equipped with gang mounted diamond blades capable of cutting a minimum of three or four slots simultaneously in each wheel path. Skewed joints or cracks may require slots longer than the length specified in the plans. Pick up and remove water and paste residue from the pavement surface immediately by means of a vacuum attachment on the sawing machine. For smaller projects, a slot sawing machine might not be feasible. Consider allowing the use of walk-behind saws for slot cutting when the project contains less than 100 retrofit bars.

Remove existing concrete from the slots followed by the cleaning out of all debris. Use maximum weight 30 pound jackhammers to remove the concrete remaining between the saw cuts. If the concrete removal operations cause damage to the pavement that is to remain, discontinue concrete removal operations and only resume after taking corrective measures. During concrete removal operations, use a small bush hammer as necessary to produce a flat, level surface within the slot so the backfill flows and consolidates under the dowel bars.

Complete installation of retrofit dowels, with dowel bars and backfill placed prior to reopening the lane to public traffic. Place silicone at all joints and cracks followed by the dowel bar assemblies in each slot. Following that, place patching material and then consolidate and finish patching material. Finally, diamond grind the pavement surface within 30 working days of dowel bar retrofit placement.