The New NY Bridge will be supported by an invisible, interwoven network of steel fortifications encased in more than one billion pounds of concrete. The combined strength of the concrete and the reinforcing steel bars known as rebar will enable the new bridge to serve New York for the next century or longer.
Sixty million of pounds of rebar will be used in the construction of the new bridge. The large steel bars are produced at several off-site facilities, where they are tailored to the specifications of the new bridge. The steel is bent and shaped into precise forms that are dictated by various bridge elements, including curves and even full circles. Fabricators also form grooves in the rebar to help the steel maintain a tight grip on the concrete.
Once the bars are fully formed, they are treated with a special process called galvanization, which extends the life of the rebar. The steel bars are dipped into a hot bath of liquid zinc, which forms a crystalline “skin” over them. This helps prevent corrosive factors such as salt water from rusting or otherwise degrading the steel. Fortifying the rebar is especially important for the New NY Bridge, where the brackish waters of the Hudson River can penetrate concrete. Without galvanization, even small amounts of water or moisture could potentially compromise the rebar.
Once fabricated, the galvanized rebar is brought to the project site by barge, where the bars are tied together into place as part of the support for the new bridge’s decks, piles, piers and pillars. The skeleton-like networks of rebar are arrayed according to detailed specifications to provide maximum support, and are inspected by engineers in the field to ensure proper placement.
Once the steel bars have been tied into their proper configurations, one of the project’s floating batch plants mixes and delivers a steady stream of concrete to the formed area. The concrete flows around the steel bars as construction workers utilize vibration to ensure the concrete travels through the dense matrix of rebar and completely fills the forms.
Since its initial use in the 15th century, rebar has enabled concrete structures to stand much taller than would otherwise be possible. As the New NY Bridge rises from the surface of the Hudson River, this time-tested material is being used to ensure a long-lasting structure.