Project: Jo Johnston Ave bridges: I-40 Fast Fix 8 - Nashville, TN Customer: TDOT Contractor: Kiewit - Omaha, NE Finisher: Project obstacles and solutions: The Tennessee Department of Transportation announced that it planned to replace eight aging bridges on the I-40 outer loop on the south side of Nashville, Tennessee. Each bridge would be demolished and reconstructed over a weekend encompassing only 58 hours. At 8:00 p.m. on Friday, bridge demolition began and had to be completed 12 hours later. From there, the new bridge was constructed using an Accelerated Bridge Construction (ABC) method that would reopen the bridge to traffic on Monday at 6:00 a.m. Key to all of this was a carefully planned out construction schedule and building materials that were delivered on time and to specifications.
The two bridges that cross Jo Johnston Avenue were the first to be replaced. To expedite the construction, much of the concrete decking was precast in sections and then lifted into place. IMI was approached by Kiewit to design an alternative concrete mix to replace a bagged grout to be used to fill the voids between these precast panels. By doing this, IMI would eliminate both labor and intense man hours preparing and placing the grout. The mix had to meet a design strength of 3,000 psi in 4 hours. The mix had to be flowable and fill all the voids. Spacing between the panels varied from 8.5 - 12 inches. The concrete had to meet the early strength requirements, but also remain plastic for 45-60 minutes in order to allow for delivery and placement. The other challenges were determining the parameters for the mix and gaining approval from the site engineer. TDOT had final approval of the concrete. This mix did not fall into any categories currently set out in their specifications for ready mix concrete. IMI QC/QA worked with both the site engineer and TDOT officials to test and prove the mix would work to gain approval.
In order to meet these demands, IMI QC/QA designed a mix using Type 3 Portland Cement, along with other admixtures. This mix was able to exceed early strength requirements and kept the project on schedule.
The first bridge over the Jo Johnston Avenue was shut down on Friday, July 24 and reopened on Monday, July 27. The second bridge was torn down and reconstructed between July 31 and August 3. Watch a fast track video on this project.