How to Finish a Concrete Deck Bridge

Skid-resistant surfaces are essential for roads, and especially for bridge decks, where vehicles have limited area to recover from loss of control. A textured concrete finish provides skid resistance, with the degree of texture varying according to the design speed of the road. Generally, a grooved surface, formed with metal tines, is the most dependable finish for a bridge deck surface. The grooves help facilitate drainage, another important issue in bridge deck design. Longitudinal grooves create less noise than transverse grooves, but the latter is preferred, because of improved drainage.

Concrete mix with crushed, fine aggregate
Mechanical screed
Shovels
Masonry hoes
Trowel (optional)
Bull float (optional)
Broom, stiff-bristle type (optional)
Straightedge, lightweight, 10 feet long
Burlap, sized for bridge deck
Combs with wire tines
Curing compound (optional)

Instructions

- 1
  Form the concrete for the bridge deck according to specifications. Pour the concrete slightly ahead of finishing tasks. Move the screeding operation about 6 inches ahead for every pass across the deck, striking off -- leveling -- every square inch of the surface.
- 2
  Roll a thin bead of concrete in front of the screed to strike off the concrete at the desired level. Use shovels or masonry hoes to pull back the bead of concrete in front of the screed, when it becomes too large for the screed to level the concrete properly.
- 3
  Apply the initial finish immediately after the screed passes. with the bull float, trowel, or broom. Close the surface and eliminate bumps and low spots left by the screed.
- 4
  Check the bridge surface with the lightweight 10-foot straightedge every 5 feet longitudinally, and every 2 feet across. Fill depressions with fresh concrete and remove high spots. Level the surface with the large float.
- 5
  Drag burlap over the concrete while the sheen of water is still on the surface. Keep at least 3 feet of the burlap in contact with the surface for the full width of the bridge deck.
- 6
  Form grooves in the surface using combs with metal tines after the burlap drag finish, where speeds are expected to exceed 40 miles per hour. Apply the grooves transversely -- across the bridge deck -- to encourage drainage.
- 7
  Make the grooves 1/8 inch wide and 1/8 inch deep, spaced 1/4 to 1/2 inch apart. Leave 12 inches next to the curb unfinished, to ease drainage.
- 8
  Cure the bridge deck in the recommended manner for the conditions. Apply curing compound at a heavier rate than normal for a heavily textured surface.

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