Overview of Bridge Joint Noise IssueExpansion and contraction caused by temperature changes, shortening and creep caused by pre- stressing, deflections caused by live loads, and longitudinal forces caused by vehicular traffic all combine to produce nearly continuous motion in highway bridges. Bridge expansion joints are designed to permit the longitudinal movement and small rotations presented on bridge decks due to changes in environmental condition, live loads, and physical changes on the structural materials such as creep and shrinkage. While there are many types of bridge joint systems, they can be classified as either open or closed joint systems.
Cause of General Bridge Joint NoiseNoise events due to vehicles passing over bridge expansion joints occur when vehicle tires strike the rectangular face of the expansion joint units and traverse the discontinuous surface profile. It can also be induced by the unevenness of the surface of the expansion joint itself and of the road surface before and after the joint. In the case of the West Waters Avenue Bridge, steel armor on the joint has come loose exacerbating the problem.
Application of Acoustiblok Material
- Acoustiblok was positioned on the concrete to form an acoustic barrier at the joint. For this test, it was fastened directly to the concrete at the top and bottom using Silicoflex locking adhesive.
- All joint gaps were sealed at the noise source to create the acoustical barrier.
- Total testing time was approximately 4 hours with the majority of that determining the best positioning of the Acoustiblok material.
- The material was applied with the goal of reducing as much noise as possible, creating the most aesthetically looking noise barrier possible.
- It took approximately 1.5 hour to apply the Acoustiblok material once a design was determined.
Range “without Acoustiblok: 72.4 -105 dBA Range “with” Acoustiblok: 69.8 – 83.5 dBA
Pressure Reduction: 99% with Acoustiblok material
Perceived Reduction: 73% in bridge joint noise with Acoustiblok material