Procedure for Grooving Concrete Bridge Decks

The Process

• A bridge grooving machine moves across the width of the bridge's concrete surface and uses diamond-tipped saw blades, mounted on a horizontal shaft, to cut grooves into the cement. The machine includes a powerful vacuum system to lift the concrete dust and debris into a holding tank for later evacuation. Cooling water, pumped from a tanker, is sprayed upon the concrete to protect the blades from friction-induced heat. The grooves allow for both water drainage and displacement.

Department of Transportation Specifications

• State departments of transportation (DOTs) and provincial jurisdictions throughout the United states and Canada specify that grooves must be between 1/8 and 1/16 inch deep and 1/8 inch wide. Spacing differs in each area but grooves are typically minimally cut 3/4 inch from the center of one groove to that of the next. Grooving the deck at right angles to the center line of the roadway provides optimum traction and water drainage.

Additional Benefits

• A properly grooved new or rebuilt bridge deck allows for the immediate application of chemicals used to cure the cement that was laid on the surface of the bridge roadway. This saves both time and money for cash-strapped DOTs struggling to maintain or replace crumbling bridges, and other elements of roadway infrastructure, in the face of rising manpower and material costs.

Grooving Versus Tining

• Bridge design engineers try to reduce the pooling of water on the concrete surface of a bridge deck by texturing the concrete using a process known as "tining." A metal rake, drawn by hand through the yet unformed cement, produces a textured, high-friction surface. Unfortunately, tining does not bring about uniformity in either the grooves produced or in their depth. Freshly laid concrete, modified by latex, is difficult to tine as it is too fluid, while unaltered cement often dries too quickly to get the deck tined. Machine-grooving cured concrete is much more reliable.