Fast Track Hydrodemolition and Latex Modified Concrete
A project to rehabilitate various features of the Mississippi River Bridge on I-20 at Vicksburg, MS is ongoing through 2020. The work includes major structural repairs to the bridge superstructure and upgrades to the electrical system on the bridge. Another critical component of the project though is repairs to the bridge deck on the 2-mile long structure. The project is being administered by the Louisiana Department of Transportation Development (LaDOTD). The deck work is significant in that it is one of the largest fast track hydrodemolition jobs ever administered by the department, with a total of 65,000 square yards of total surface restoration. American Contracting & Services, Inc. (ACSI) is performing the deck rehabilitation for the prime contractor OCCI, Inc.
Work on the bridge deck by ACSI started up late in January, and was met with inclement weather for much of the first six weeks of construction. The work progress has picked up momentum as the project moves into the summer. The westbound spans have now been completed and work is just getting started on the eastbound direction.
This project is employing a combination of milling and a ½” fast track hydrodemolition cut to the mortar line in order to selectively remove just the deteriorated concrete in the deck, and provide the final very roughened profile, ideal for the concrete overlay installation. An inlay of a minimum of 1 1/2” of Latex Modified Concrete is going back down as the finished surface. This surface preparation and high performance concrete will give the bridge deck a good 25 or more years of extended service life. The deck work is on schedule for a planned completion in the fall of 2020.
Mid-America Milling Company, LLC (MAMCO) is performing the milling of the concrete surface, which includes a removal depth of approximately 1 ¼” of the top deck surface. MAMCO milled 32,805 SY in the westbound phase. Behind the milling, Hydro-Technologies, Inc., is performing the fast track hydrodemolition cut to gain the selective removal of all deteriorated concrete. The 15,000+ psi waterblast is also carving out the final profile needed at the deck interface to gain an exceptional bonding surface for the concrete overlay system.
The overlay concrete is a high performance latex modified concrete (HPLMC). HPLMC is a very dense concrete that is ideally suited for bridge deck overlays. It has been time tested for 50 years within the United States. BASF is supplying the latex for the HPLMC for this project.
Modified Concrete Suppliers, LLC is the producer of the HPLMC on site, with ASCI placing and finishing the concrete. The nominal overlay thickness is 1 ½” although deeper areas of concrete were poured where selective removal occurred due to deteriorated deck concrete. The total amount of HPLMC poured on the westbound lanes was 1700 cubic yards. A similar quantity is expected for the eastbound lanes that are currently under construction.