ForConstructionPros.com

Being the second largest state in the country, as well as the second most populous state, Texans have a "do it up big" approach to life, but there are times when a finer approach is needed. That was the case this past summer when TexOp Construction opted to use a fine-toothed drum mounted on a Wirtgen W 2000 cold milling machine to precisely prepare the surface of the President George Bush Turnpike for a new thin overlay.

The Turnpike is a major east-west route in the northern half of the Dallas Metroplex, and is a 30.5-mile, six-lane, limited access toll highway which passes through or along the cities of Garland, Richardson, Plano, Dallas, Carrollton, Farmers Branch and Irving.

Near Carrollton, TX, the project owner — the North Texas Tollway Authority (NTTA), planned to overlay a section of the expressway with NovaChip high-performance, proprietary open-graded friction course. But such thin lifts — with maximum 3/8-in. stone — require extremely well-prepared and even surfaces for placement. Any irregularity in the existing pavement will reflect through the thin surfacing immediately. Conventional surface prep for worn pavements previously involved diamond grinding the pavement to precise tolerances, involving specialized mobile equipment, excessive lane closures and long project times.

But cold milling subcontractor TexOp Construction, LP, of Roanoke, TX, and Wirtgen America Inc. had a different idea. In conjunction with its general contractor APAC, TexOp proposed using a W 2000 with a 6.56-foot fine-texture drum to prepare and level the aged asphalt pavement surface prior to the thin surfacing.

The Wirtgen fine-toothed drum removed all imperfections and bumps, and leveled the driving surface side-to-side, so a NovaChip surface could be placed using a Vögele 1800 SP paver. The NovaChip paving process places an ultra-thin, coarse aggregate hot mix over a special asphalt membrane applied in one pass over the existing pavement surface.