In recent years, progress in bridge repair techniques and technologies has promised more options for strengthening the existing bridge heap, which eliminates the need to redirect both water and traffic. This project examined the experiences of other countries with several products on the market and offered the Minnesota engineers the opportunity to evaluate two provider systems on a restored bridge.
The repair of the in-water foundation of a bridge is a critical and challenging undertaking. The traditional approach to reinforcing elements below the water surface includes the construction of a temporary wall that surrounds the area and continuously pumps to keep the area dry. This approach can also include removing the bridge deck in order to offer easier access for heavy equipment and diversion transactions and vehicle traffic until the work is completed.
Several systems available in stores with innovative methods and materials such as fiberglass -reinforced plastic forms (FRP) or jackets and steel reinforcements can remain open to traffic, while underwater repairs are completed, which eliminates the disorders and the environmental effects of traditional practices. In order to evaluate the effectiveness and performance of these products under real conditions, Mndot and LRRB have teamed up in a research project to put two provider systems near St. Cloud on a bridge and to compare the installation processes, long -term effectiveness and inspection recommendations that are connected to every solution.
What did we do?
The project began with a review of repair projects in water bridges that were completed in other states, and with a survey of bridge owners from all over the country to understand their experiences and the current state of practice to repair bridges with corroded in-water foundations.
Based on these preliminary efforts, two proprietary product systems – both consisting of a FRP jacket, specially formulated joint mortar and accessories – were selected to be installed on a bridge in central -Minnesota with stacks that needed structural reinforcement.
“This project enabled us to put a promising repair strategy into practice and to see the process first -hand on a Minnesota bridge. Now engineers across the state have a practical option to carry out these demanding repairs with minimal traffic disorders. “Said Nick Haltvick, civil engineer of the North Region Bridge, Mndot Office of Bridges and Structures.
The installation process for both systems was almost identical: Specialized diving contracts presented the 14 piles of each bridge by first clearing rocks and debris from the area and using a pressure washing machine to clean the structure under the water surface.
The steel reinforcement was laid around every stack, which was then surrounded in a FRP jacket. After the connections had sealed the joints with an epoxy, the bridge workers pumped into the jacket, they heal, and then changed a final epoxy coating up to make the system waterproof.
The steps to install each system were documented to compare processes, identify improvements and to result in the lessons obtained. About a year after the installation, some of the FRP jackets were removed so that inspectors see the results and recommend changes.
What was the result?
Both systems were practical options for repairing stacks in water bridges and are expected to extend the lifespan of the test bridge by at least 20 years. Several strategies have been identified during the entire installation process to help Minnesota engineers to increase efficiency and to improve the results for future projects.
Before construction, an inspection of the underwater conditions should be carried out at the location in order to identify potential risks and develop a complete scope and a plan for repairs. This inspection should evaluate the visibility below the surface, measure the flow rate, determine the type of channel material below the bridge and determine the extent of the structural deterioration in order to offer the contractors a more precise amount of work and avoid costly project changes.
Access to the area should also be taken into account in advance, as this can determine the equipment that is required and whether tasks such as the removal of rubble would have to be carried out manually.
According to the manufacturer's instructions during the entire installation process, it is of crucial importance for the quality and long -term performance of the repairs. If you make sure that the pile surfaces are thoroughly cleaned, you can directly influence the material adhesion and determine the overall project success.
After construction, the FRP systems should only require minimal maintenance, but routine inspections and checks should be carried out after large storms are carried out to quickly identify and address damage.
What's next?
This project gave the engineers from Minnesota an improved understanding of the costs and advantages of this innovative approach to repair bridges with water heaps. If the state bridges continue to age, this solution is probably implemented more often to increase the lifespan of the aging infrastructure of Minnesota.