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Lafarge Agilia SCC, NewCem specs hold water for Virginia tunnel elements

Lafarge North America is playing a major role in the construction of a 4,800-ft., two-lane tunnel under the Elizabeth River in Hampton Roads, Va. Adjacent to the existing U.S. 58 Midtown30-NS-Lafarge-400 Tunnel, the West Midtown Tunnel will double traffic capacity between the cities of Norfolk and Portsmouth, helping to alleviate congestion while separating tightly confined eastbound and westbound vehicles.

At a large dry dock in Sparrows Point, Md., a Lafarge team is working to build the tunnel’s 11 rectangular reinforced concrete elements. Each comprises five sections that require separate concrete pours. Two portable on-site batch plants are producing 72,000 yd. of Lafarge Agilia self-consolidating concrete mixes, designed with the producer’s NewCem slag cement. Agilia mixes significantly reduce construction time and cost by eliminating the need for vibration due to their fluid and stable properties. Engineered for high strength and long-term durability, NewCem slag cement helps control shrinkage, creep and cracking in mass concrete structures.

30-NS-TunnelII-400The first six concrete elements arrived at the Hampton Roads site in mid-2014, after being towed 220 miles down the Chesapeake Bay. The remaining five tunnel elements are scheduled to arrive at the Portsmouth Marine Terminal this spring. In October, the Elizabeth River Tunnels Project Team placed by immersion the first precast section of the West Midtown Tunnel, which will eventually serve as the westbound exit to Portsmouth.

Since the original tunnel opened in 1962, traffic along the U.S. 58 stretch has increased 600 percent. Once the new tunnel is completed in Q4 2016, the existing one will be rehabilitated; together they will expand capacity to two lanes of traffic in each direction.