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ASA Outstanding Shotcrete Awards Program

The ASA Outstanding Shotcrete Project Awards Program exists to recognize excellence and innovation on projects in which the application of shotcrete has played a significant role.

ASA’s Annual Outstanding Shotcrete Project Awards Program provides an exciting real-world demonstration of the exceptional advantages of placing concrete via the shotcrete process. Many sustainability advantages are also inherent in the shotcrete process and play a significant role in winning projects as well as the project owner’s ultimate decision to use shotcrete as the method of concrete placement. Projects must be completed between January 1, 2021, through September 1, 2023, and can be submitted in the following areas: Architecture │ New Construction, Infrastructure, International Projects, Pool & Recreational, Rehabilitation & Repair, Underground.

To assist in your submission, we have provided submission resources to inform you of the submission guidelines, a list of questions, and a copy of the owner release form. Please email any questions to [email protected].

Award Archive

2023 – Nineteenth Annual Outstanding Shotcrete Project Awardees

Outstanding Architecture | New Construction Project

American Museum of Natural History, Gilder Center | New York, NY

Project Name:
American Museum of Natural History, Gilder Center

Location:
New York, NY

Shotcrete Contractor:
COST of Wisconsin Inc.

Architect/Engineer:
Studio Gang

Material Supplier/Manufacturer:
Tec-Crete Transit-Mix Corp

Equipment Manufacturer:
REED Shotcrete Equipment

General Contractor:
AECOM Tishman

Project Owner:
American Museum of Natural History

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Outstanding Infrastructure Project

Ross Street Underpass | Salmon Arm, BC, Canada

Project Name:
Ross Street Underpass

Location:
Salmon Arm, BC, Canada

Shotcrete Contractor:
Ocean Rock Art Ltd and LRutt Contracting Ltd.

Architect/Engineer:
Binnie Civil Engineering Consultants

Material Supplier/Manufacturer:
Salmon Arm Ready Mix

Equipment Manufacturer:
REED Shotcrete Equipment

General Contractor:
Kingston Construction

Project Owner:
City of Salmon Arm, BC

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Outstanding International Project

Shotcrete as Roadside Slope Protection in Brazil | SP 333 Highway, São Paulo, Brazil

Project Name:
Shotcrete as Roadside Slope Protection in Brazil

Location:
SP 333 Highway, São Paulo, Brazil

Shotcrete Contractor:
Unicom Construções e Tecnologias and Construtivas LTDA

Architect/Engineer:
APG Assessoria Projetos Geotecnia

Material Supplier/Manufacturer:
MCC Muriam Concreto LTDA

Equipment Manufacturer:
Schwing Stetter / Tunelmak

General Contractor:
Entrevias Concessionária de Rodovias S.A

Project Owner:
Entrevias Concessionária de Rodovias S.A.

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Outstanding Pool & Recreational Project

Shaw Residence | Duck, NC

Project Name:
Shaw Residence

Location:
Duck, NC

Shotcrete Contractor:
Artisan Pools NC

Architect/Engineer:
Waterforge and Kitty Hawk Engineering

Material Supplier/Manufacturer:
CnL Concrete

Equipment Manufacturer:
REED Shotcrete Equipment

General Contractor:
Artisan Pools NC

Project Owner:
Greg and Vicky Shaw

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Outstanding Repair & Rehabilitation Project

O’Hare Plaza West Drive and Executive Garage Restoration | Chicago, IL

Project Name:
O’Hare Plaza West Drive and Executive Garage Restoration

Location:
Chicago, IL

Shotcrete Contractor:
Bulley & Andrews Concrete Restoration

Architect/Engineer:
WGI

Material Supplier/Manufacturer:
Sika STM/Glenrock;

Equipment Manufacturer:
REED Shotcrete Equipment

General Contractor:
Bulley & Andrews Concrete Restoration

Project Owner:
JLL

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Outstanding Underground Project

Rondout Bypass Tunnel | New York, NY

Project Name:
Rondout Bypass Tunnel

Location:
New York, NY

Shotcrete Contractor:
Patriot Shotcrete

Architect/Engineer:
DELVE Underground

Material Supplier/Manufacturer:
Bonded Concrete

Equipment Manufacturer:
Western Shotcrete Equipment

General Contractor:
Kiewit Shea Constructors, AJV

Project Owner:
New York Department of Environmental Protection

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Honorable Mention Project

The Neville Island Bridge | Coraopolis, PA

Project Name:
The Neville Island Bridge

Location:
Coraopolis, PA

Shotcrete Contractor:
Sofis Company Inc.

Architect/Engineer:
SAI Consulting Engineers

Material Supplier/Manufacturer:
The Quikrete Companies

Equipment Manufacturer:
Gunite Supply & Equipment Co.

General Contractor:
Trumbull Corporation

Project Owner:
Pennsylvania Department of Transportation

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Honorable Mention Project

Moyie Dam Repair | Bonner’s Ferry, ID

Project Name:
Moyie Dam Repair

Location:
Bonner’s Ferry, ID

Shotcrete Contractor:
S & L Underground

Architect/Engineer:
JUB Engineering

Material Supplier/Manufacturer:
Oldcastle Precast and REED Concrete Pumps

Equipment Manufacturer:
REED Shotcrete Equipment

General Contractor:
S & L Underground

Project Owner:
City of Bonner’s Ferry, ID

Shotcrete Consultant/Quality Inspections:
Leo Waddell, Shotcrete Consulting

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Honorable Mention Project

Water’s Edge | Greenwich, CT

Project Name:
Water’s Edge

Location:
Greenwich, CT

Shotcrete Contractor:
Drakeley Pool Company

Architect/Engineer:
James Doyle Design Associates

Material Supplier/Manufacturer:
O&G Industries

Equipment Manufacturer:
Schwing America

General Contractor:
Drakeley Pool Company

Project Owner:
Nordic Custom Builders

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The Jetcreter – The First Continuous-Feed, Dry-Mix Gun

During the summer of 1970, on my 18th birthday, my father woke me up and told me they needed me on a job. I drove out that morning in July to the Crucible Specialty Steel plant in Midland, PA. It was my first experience working on a Gunite job. We were gunning refractory in a vessel, and I was throwing 100 lb (46 kg) bags of pre-packaged refractory into a paddle mixer to pre-dampen the material. We emptied the paddle mixer on sheets of plywood and shoveled the pre-dampened refractory material into the dry-mix shotcrete gun’s hopper. The Jetcreter was a continuous-feed gun, and it was tough for us to keep up with it. It was a very long day for me because it took 15 hours to complete the gunning. I left the house that morning in the dark and returned home in the dark. That was my introduction to “Gunite” (now referred to as dry-mix shotcrete).

Mapei’s London Underground Bank Station’s Capacity Upgrade

Deep in the heart of London’s financial centre, work has been continuing to make one of the world’s largest stations safer and easier for passengers to use. Finding your way around the existing labyrinth of tunnels, connecting five London underground lines, is a task worthy of the most experienced navigator.

Advances in Shotcrete Technology for Ground Support in Tunnels and Mines in North America

In recent years, shotcrete has been widely used for ground support in civil tunnels and mines in North America. Shotcrete technologies have advanced with robust robotic sprayers, high-performance shotcrete mixture designs, and high-performance fiber reinforcement in conjunction with rigorous qualification of shotcrete nozzlemen and QC inspection and testing programs. Design engineers and contractors are using shotcrete more and more often for various underground applications including ground support and final linings in tunnels in soft ground and hard rock mines, as well as in repair and rehabilitation projects in railway tunnels and other underground openings. Large underground caverns have been constructed using shotcrete as the initial liner in San Francisco and Los Angeles, and for both the initial liner and final liner in New York and Washington D.C. This article focuses on recent underground shotcrete technology developments from project experience and provides lessons learned. It also demonstrates that proper quality control and shotcrete qualification programs are critical for successful shotcrete projects.

Earth and rock excavations are effectively stabilized with shotcrete and a variety of reinforcement and anchoring systems. Using shotcrete to stabilize soil for excavation has advantages over traditional timber and steel shoring techniques. Shotcrete is also ideal for ground support in tunneling and mining. It provides early ground support after blasting or excavating; early strength development, which provides flexibility to allow for ground stabilization and stress relief; and offers the ability to conform to the natural irregular profile of the ground without formwork, making it ideal for any tunnel. It is also the preferred material/process for underground stations, side drifts, and shops, and provides long-term stability. It can be used as a final or permanent lining for underground structures.

The ASA Technical Questions and Answers is a free service offered to all users, but primarily intended for engineers, architects, owners and anyone else who may be specifying the shotcrete process and/or has need for a possible answer to a technical question.

User agreement: The answers provided to submitted questions are intended for guidance in planning and executing shotcrete applications. This information is intended only for the use of individuals who are competent to evaluate the significance and limitations of its content and recommendations, and who will accept responsibility for the application of the material it contains. The American Shotcrete Association provides this information based on the best knowledge available to them and disclaims any and all responsibility for the information provided. The American Shotcrete Association will not be liable for any loss or damage arising therefrom.

If you are unable to find what you are looking for in the archive, then submit a new technical question.

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    We have a wet-mix shotcrete steel fiber overhead application progressing in our state. The question is about the use of a steel trowel finish, as opposed to say a magnesium or wood float finish. In the ASA Shotcrete Inspector seminar, it was stated that a steel trowel is less durable, reduces freeze-thaw resistance and shows cracking more proximately. As this particular application is overhead and, in a tunnel, there is not as much of a concern with water infiltration and the associated freeze-thaw exposure. We usually don’t allow steel trowels for flat work, due to deicing salts, but that concern wouldn’t apply here. My superintendent has asked me to reach out to you to see if you might have any further detailed advice on this type of application. Construction is wanting a smooth finish and looks do matter here as it is a high-profile project. If the DOT were to allow the steel trowel for finishing, what would be your concerns or suggestions to this approach?

    Freeze-thaw deterioration is dependent on the concrete being saturated in multiple freezing/thawing cycles. In an overhead application, where water can’t stand on the surface, the concrete can’t be saturated unless water permeates through from the upper surface. And with good quality concrete in the tunnel, water shouldn’t permeate through, so it should be functionally watertight. As a result, freeze-thaw likely isn’t a critical durability issue.

    A steel trowel finish does require extra working of the surface and would require the contractor to be very attentive to the proper time to obtain the finish yet not overly disturb the fresh concrete. Gravity is working against the overhead concrete staying in place.

    Having a smooth steel trowel finish would make minor shrinkage cracks more noticeable. However, in the tunnel without exposure to sunlight or much wind exposure, and with proper attention to curing, perhaps surface cracking will be minimal.

    I am a TBM Tunnel Engineer from India, and I was looking for information on the applicable compressed air pressure range required for a wet-mix shotcrete application (small shotcrete pump-capacity 7 CU.M/Hr) hand spraying with a 30m hose for a better-compacted mix. I would kindly request you to please send me information on the pressure range to be expected for good quality shotcrete placement of the concrete mix on the rock substrate in NATM Tunneling.

    Wet-mix shotcrete depends on air flow at the nozzle to accelerate the concrete to 60 to 80 mph (100 kph to 130 kph). Most air compressors produce their air flow capacity at 100 to 120 psi (7 to 8.4 kg/cm2) at the compressor. However, depending on the size length and couplings in the air hose, there may significant pressure drops when the air reaches the nozzle. Here’s what ACI 506R-16 Guide to Shotcrete Section 4.4.2 states for wet-mix:

    “The recommended ft3/min (m3/min) needed for the wet-mix process is between 200 to 400 ft3/min (5.7 to 11.3 m3/min) air volume at 100 psi (7 bar). Higher air volume capacities are needed for higher volume and higher-velocity shotcrete applications. If a blowpipe is to be used during the shooting process, more air will be required to run both operations simultaneously. Conducting a test during the preconstruction testing phase using a blowpipe while gunning the wet-mix material will indicate if the air compressor has enough air volume capacity to perform both tasks at the same time. Long, small-diameter lines may not provide sufficient air volume capacity, even with a large air compressor. Test and consider increasing the size of the air line.”

    Though there is no direct guidance for air pressure at the wet-mix nozzle you may consider the guidance for dry-mix air pressure in ACI 506R Section 4.4.1:

    “The operating air volume (ft3/min [m3/min]) drives the material from the gun into the hose, and the air pressure is measured at the material outlet or air inlet on the gun. The operating pressure varies directly with the hose length, the density of the material mixture, the height of the nozzle above the gun, and the number of hose bends. Experience has shown that operating pressures should not be less than 60 psi (4 bar) when 100 ft (30 m) or less of material hose is used, and the pressure should be increased 5 psi (0.34 bar) for each additional 50 ft (15 m) of hose and 5 psi (0.34 bar) for each additional 25 ft (7.5 m) the nozzle is above the gun.”

    The minimum 60 psi (4 bar) necessary for dry-mix could be applied to the wet-mix air supply as the velocity created by the air flow is similar.

    M4 M5 Link Tunnels

    The M4-M5 Link Tunnels in Sydney, Australia, is approximately 7.5 km (4.7 mi) long and accommodates up to four lanes of traffic in each direction. It connects the New M4 Tunnels with the M8 Tunnels to form the 33 km (20 mi) long Westconnex Motorway, mostly underground.