Versatile Shotcrete Applications: Tunnels & Silos

Versatile Shotcrete Applications: Tunnels & Silos

Shotcrete’s versatility continues to reshape construction and infrastructure projects across a variety of environments. From deep tunnels to towering silos, its adaptability allows contractors to meet complex structural, environmental, and aesthetic demands. This article highlights two successful case studies that demonstrate how shotcrete solves engineering challenges while delivering efficient, high-performance results.

Tunnel Shaft Liner – Washington, D.C.

The Northeast Boundary Tunnel (NEBT) project in Washington, D.C. required a vertical ventilation shaft liner connecting a 23-ft (7-m) diameter shaft to a 25-ft (7.6-m) tunnel. Contractor CROM was tasked with installing a 48-ft (14.6-m) tall shaft liner using wet-mix shotcrete as the final structural surface.

Key project elements included:

• 12 in. (300 mm) thick wall reinforced with epoxy-coated rebar
• 1.5 in. (40 mm) PVC waterstop at base
• Use of whaler rings to secure formwork and stage rebar during shooting

Given the confined underground workspace, CROM relied on a man-lift and lowering system for material and equipment. The crew installed temporary platforms to support shotcreting and finishing. The wet-mix shotcrete used steel fiber reinforcement and a proprietary admixture blend to ensure durability and workability. The project was completed in two phases, with each lift carefully sequenced for optimal curing and finish quality.

Pre-Stressed Concrete Water Tank – Florida

In Groveland, Florida, CROM constructed a 2.5 MG (9.5 ML) pre-stressed concrete tank for reclaimed water storage. With a 112-ft (34-m) diameter and 38-ft (11.5-m) height, the project required exacting control of placement, curing, and strength development in Florida’s humid environment.

Project highlights included:

• 8 in. (200 mm) thick shotcrete walls
• Full-height circumferential steel reinforcement
• Use of horizontal bands to ensure uniform curing and placement quality
• 6000 psi (41 MPa) target strength
• A double curing cycle: first with curing compound, followed by 14 days of water spray

The crew rotated through day and night shifts to keep pace with tight schedule demands. Shotcrete placement proceeded continuously, with hand finishing and screeding ensuring a uniform surface profile. The tank was completed on time, with all performance metrics exceeded during final testing.

Conclusion

These case studies highlight shotcrete’s ability to deliver high-quality, structurally sound solutions in both underground and above-ground applications. Whether used in challenging shaft conditions or expansive water storage structures, shotcrete remains a top choice for durability, speed, and adaptability across the construction industry.

Tags: Shotcrete, Tunnel Construction, Water Tanks