CROM Applies Specialty Shotcrete to Restore Silos While Fully Operational
Built in 1967 as part of a Missouri mill’s lead ore refining process, a pair of steel storage silos were in need of restoration. The original structural shell had damages and many areas were corroded from age, use and environmental degradation.
CROM was selected as the specialty shotcrete contractor to solve a two-fold challenge:
- create an interior shotcrete liner to restore the silos and
- complete the restoration while keeping the refining process operational.
Preparation
Prior to CROM’s shotcrete application, the general contractor addressed all defects and holes in the bin walls.
The general contractor’s team designed, cut, and removed a section of the bin wall for CROM to place its Vehicle Mounted Aerial Platform (VMAP) which provided safe access for shotcrete nozzlemen and finishing craftsmen.
The hopper floors were leveled off with existing ore to provide the base for staging the VMAP and workable platform, and to remove shotcrete rebound and debris associated with the liner. When set up was complete, CROM began the process of applying shotcrete to the walls.
Specialty Shotcrete Application
CROM craftsmen applied wet mix shotcrete over the existing steel supporting members and attached it to the shell using welded Nelson studs and a mat of reinforcing bars tied at 12 in. on center each way.
The 5,000-psi designed wet mix shotcrete was applied in successive layers until the section thickness of 8 in. was achieved with a tolerance of plus or minus ½ in. The final application of shotcrete received a fine-broomed finish.
Through a competitive bidding process, CROM was selected to perform the complete scope of work, which included not only restoration and repairs but also a plan for keeping the plant operational. CROM safely and efficiently delivered:
- Custom-built fiberglass gates that created a bypass to allow half of the Headworks to remain in operation at a time while work was performed. Watertight seals ensured a safe, healthy and sanitary condition for our team members.
- Hydro blasting all interior surfaces to remove deteriorated and contaminated concrete
- Replacing structurally compromised reinforcing steel.
- Performing crack repair, resurfacing, and applying high-performance coatings to all concrete surfaces to restore to like-new condition.
- Removal and rehabilitation of weir gates.
- Rehabilitation of gate connection points to effluent boxes.
- Applying a complete specialty coating system, custom designed by Tnemec, for the toxic environment present in the wastewater headworks.
Through its efficient Design/Bid/Build approach, wide scope of services, innovative solutions and commitment to health and safety, CROM delivered a like-new Headworks facility while providing uninterrupted service to the Gainesville community.
