November 1, 2016
Even contractors with the best intentions miss critical elements that can cause parking structure restoration projects to be short-lived. If a contractor makes even the slightest mistakes, hundreds of thousands of dollars could be wasted, while significantly reducing the useful life of your parking structures. Here are three pitfalls we often encounter when a consultant has not been involved:
Shear tabs between the precast tee panels are the first to corrode and have the welds break after only a few winter seasons of exposure to deicing salts if the joint sealants between the panels fail. When one shear tab fails, it exerts more stress to the neighboring shear tabs. If enough shear tabs fail, the precast tee panels will move independently from each other. If a contractor simply replaces the joint sealant, the sealant will fail or be ineffective almost immediately, since the precast panels can now move independently from each other.
Another typical repair issue with precast structures is the welded connection between the precast tee panels and the facade spandrel panel. The top floor is the most susceptible, since it is exposed to weather and snow removal with snow plows. The welded connection can fail due to rust corrosion of the connection, or the slotted connection does not function properly. If the connection fails, the surrounding concrete will delaminate and spall. If a contractor simply engages in repairing the spalled concrete, while the connection is still corroding, this will spall the new concrete in a short period of time.
Another common precast structure repair issue is when the bearing ends of the precast tee panels are corroded. Many contractors will simply knock down the delaminated concrete, and then apply a thin set mortar over the repair area. This is a short-term solution. The corroded rebar, which created the initial delamination and spall, will quickly spall the new repair material. The proper repair is to completely expose the corroded rebar, inspect it for section loss and possible replacement or reinforcement, properly treat the rebar and exposed concrete surface, and install new concrete repair material.
For the last 25 years, StructureTec has provided facility managers and building owners with long-lasting, cost-effective repairs, tailored to meet their unique restoration needs. We work with our clients to develop technically correct solutions that address the root cause of the problem. In addition, our repair designs are proven to extend the service life of existing structures and provide the maximum return on investment. By providing on-site construction management, we verify that the selected contractor accurately performs the scope of work laid out by our experts.
WHAT WE DO
StructureTec is a building envelope, pavement, and roof consultant specializing in the waterproofing and restoration of existing building envelopes, roofs, pavement and concrete structures.
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