One of the critical elements in a successful paving project is the asphalt mix design. Another term for mix design is the “job mix formula” or “JMF”. The two main components in hot mix asphalt are mineral aggregate and the liquid asphalt binder. To develop a successful JMF, an aggregate type, typically determined by the area geology, along with an asphalt binder type are required. This is accomplished by reviewing the available aggregates and their gradations (the size, structure and distribution of the stone), selecting the applicable aggregate profile and combining the selected aggregate with the calculated ratio of asphalt binder.
When completed in 2018, the new twin span Tappan Zee (re-named the Governor Mario M. Cuomo) Bridge will have cost $3.9 billion dollars. The Bridge will be one of the widest cable-stay bridges in the world. It will have a combined deck width across both decks of almost 184 feet and it is approximately three miles in length. It is a critical transportation link in the New York Metropolitan area. The west bound span, connecting Rockland County, New York with Westchester County, New York, was opened in August of this year. The east bound span is expected to be completed Summer 2018. The Bridge will have total of eight travel lanes and a separate shared use path for pedestrian and bicycle use. The new Bridge was built by Tappan Zee Constructors (TZC), a design-build company composed of the Fluor Corporation, American Bridge Company, Granite Construction Northeast and Traylor Bros.
Asphalt has been used on bridge decks for over 100 years with the intent of providing an effective road surface area for traffic and limited water-proofing properties. Historically, standard materials have functioned well without the need for modification but as traffic volumes and loads have increased, demand has necessitated a shift to high- performance surfacing materials.