DAVIDSON COUNTY, TN, USA

Rubblization: I-440, Nashville, TN

In 2019 the Tennessee DOT (TDOT) awarded its largest ever construction contract to Kiewit Infrastructure South Co. (Kiewit) for the reconstruction of I-440 in Nashville from Interstate 40 to Interstate 24. The existing 7.6 miles of four-lane concrete pavement was constructed in the 1980’s and had reached the end of its service life. TDOT decided to add a lane in each direction due to the significant increase in traffic volumes and to replace the concrete with an asphalt pavement. The contract was let as a Design-Build contract with an A (cost) + B (time) bid evaluation. Kiewit was the low bidder with a cost of $152,959,352 and 708 construction days equal to $70,800,000.

Kiewit’s engineers worked with TDOT and Antigo to develop a design that utilized concrete pavement rubblization and asphalt overlay to reduce time, cost, natural resource usage and greenhouse gas emissions.  In areas where rubblization and overlay was not feasible due to overhead structure clearance requirements and other limitations, Kiewit developed an alternative design that included crushing the rubblized concrete with a mobile crusher on the grade and then laying the material as a crushed base with cement treatment as a base for the new asphalt pavement. The project was divided into two sections based on subgrade support.  Section A with lower support (CBR 4) was constructed with 8.75” of asphalt over the rubblized concrete or 10.50” of asphalt over the cement-treated crushed base. Section B with greater support (CBR 8) was constructed with 7.75” of asphalt over the rubblized concrete or 10.00” of asphalt over the cement-treated crushed base.  As compared to traditional remove, haul and replace reconstruction practices, the combination of rubblization with remove and recycle in place techniques greatly reduced the truckloads of material being hauled from and to the construction site.  This produced a significant safety benefit by reducing trucks merging into and exiting from live traffic lanes.  Greenhouse gas emissions were reduced due to less truck travel and reduced need for the production of new aggregates.

Antigo used a combination of Badger Breakers® (types MHB, MHBT and T8600) and a vibratory “Z”-grid roller to perform the concrete pavement rubblization. The project phasing required Antigo to mobilize equipment operators and/or equipment to the job site twenty-three times.

The I-440 Reconstruction Project is an excellent example of Antigo’s ability to partner with owners and contractors to safely build cost-effective, long-lasting pavements while minimizing construction time and greenhouse gas emissions.