Supporting Manufacturer’s Cable Tower with Design-Build and Terra-Crete
Hickory, North Carolina
One of the challenges during retrofit construction is that consideration to future expansions are not typically planned for during the initial design and implementation of the structure. This was particularly evident at one cable manufacturer’s Cable Towers project in Hickory, North Carolina. Geotechnical specialist UMA Geotechnical Construction assisted with the intricate design-build implementation of an excavation support system, micropile underpinning system, and low-density cellular concrete (LDCC) to facilitate a cost-effective, low-vibration, and fast solution to limit disturbance to other facility activities.
UMA’s first step was to design an excavation support and underpinning system to install the retrofit tower foundations below the existing floor elevation. To construct this system, the team designed and installed a soil nail wall along the critical portions of the structure that could not be sloped. Micropiles were installed at existing caissons prior to any excavation to mitigate settlement after the soil was removed.
After considering a number of backfill materials, UMA selected Terra-Crete LDCC. Terra-Crete is a proprietary mixture of cement, water, and Aerix Industries’ AERLITETM foaming agent. By utilizing Terra-Crete with the central Aerix Industry product, UMA was able to efficiently and effectively provide an excavatable backfill material which facilitates the ability to expand the structure again at a later date.
The use of Terra-Crete provided the low-vibration and speedy backfill solution needed to support the continual operation the cable manufacturer’s building during the project, while also providing the flexibility needed for future renovations. Because it is easy to install, Terra-Crete also significantly reduced the construction time required for the excavation backfilling by eliminating the need to compact lifts of traditional soil backfill, while enabling the project to continue at a pace that exceeded the general contractor’s and owner’s expectations