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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, 2022, through September 1, 2024, and can be submitted in the following areas: Architecture │ New Construction, Infrastructure, International Projects, Pool & Recreational, Rehabilitation & Repair, and 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.

Shotcrete’s ability to encapsulate dense structural rebar support makes it an ideal candidate for seismic retrofits or other structural support elements.  The high velocity compaction of shotcrete placement and real-time visual inspection of placement make shotcrete a valuable placement method where proper encapsulation is difficult to see and access.

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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    ACI 318-14 (Building Code Requirements for Structural Concrete) requires post-installed expansion anchors to meet the testing criteria of ACI 355.2-07 (Qualification of Post-installed Mechanical Anchors in Concrete). ACI 355.2 specifies certain anchor testing and evaluation requirements to verify suitable anchor performance and to determine other aspects (such as failure mode) to use in conjunction with Chapter 17 of ACI 318 when designing the post-installed expansion anchors. Anchor testing is required largely to be performed by an independent agency and normally is conducted in normal weight and/or light weight concrete that meet pertinent ACI, ASTM and other requirements. Some post-installed expansion anchor manufacturers (like Hilti) have not had their anchors tested per ACI 355.2 in shotcrete type concrete, only tested in normal weight and light weight concrete. As such, these anchor manufacturers typically do not publish/offer any permitted load ratings, installation torques or other design and installation requirements for their expansion bolts when used in shotcrete. Instead, they recommend site testing to determine anchor performance or that the responsible design engineer can make an engineering judgment on anchor acceptability, as appropriate, if site testing is not performed. Do you have knowledge of any expansion bolt manufacturers that have tested their products is typical shotcrete? If yes to #1 above, do you know if the testing was done per ACI 355.2 requirements?

    Shotcrete is a placement method for concrete. With proper equipment and placement techniques, concrete shotcreted in place will have strength, unit weight, permeability, and other hardened properties equivalent or superior to cast concrete consolidated by vibration. Due to delivering concrete material through relatively small diameter lines (1.5 to 2 in.) [38 to 51 mm] concrete mixtures for shotcrete placement typically limit the maximum coarse aggregate size to a nominal 3/8 to ½ in. (9.5 – 13 mm) size.

    Thus, answering your specific questions:

    1. We are not aware of any expansion bolt manufacturers tests that used shotcrete placement of concrete for their test samples. However, tests on cast concrete should be equivalent with a given compressive strength and aggregate size/type in the concrete mixture.
    2. We expect that as answered in #1, that the tests run with ACI 355.2 requirements in cast concrete would have similar results when used with shotcrete placement of the concrete mixtures with similar hardened properties.

    Also, note that ACI 318-19 directly includes shotcrete as a placement method for structural concrete.

    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 was taught in engineering courses that conventional concrete should not be counted on to carry tensile stress. For steel reinforced concrete, the reinforcing bar is designed to carry all tensile loads. Although concrete obviously has some tensile strength, it is too low and prone to cracking failure to consider it in design. In fact, I believe you can assume it is cracked from the shrinkage during curing. Is gunite treated the same way? I have a pool that is developing a crack through an elevated wall/beam and down into the plaster to the bottom floor at the sun shelf. I witnessed the plumbers cutting some rebar in the beam to allow for PVC plumbing to water sheer (up at top of beam, just under the tile topping) and I worry this is the root cause along with settlement that put the top of the beam in tension. The rebar down low should be intact and I hope the crack width may stay minor down in the plaster. On top of the tiles beam where the maximum tensile stress would have been, the crack is fairly wide. The crack movement opened up a gap in the grout line between tiles of about 0.08 to 0.10 in. (2-2.5 mm). I think it was a real sin for them to have cut the rebar. If it is necessary to reinforce the tensile side to halt future movement, I would think cutting a slot or two in the gunite across the crack (say 12 in. [300 mm] each side. Up high just under the water sheer) and epoxy a rebar in the slots.

    Shotcrete, both dry-mix (gunite) and wet-mix are a placement method for concrete. Wet-mix uses premixed concrete while dry-mix simply adds water to the concrete materials at the nozzle. Both dry-mix and wet-mix with proper materials, equipment, and placement with produce quality concrete sections. The embedded reinforcement in the pool shell is designed to carry tensile loads. This may be bending stresses from structural loadings (settlement or water/backfill), or volume changes from drying shrinkage and temperature changes. Cutting a reinforcing bar would certainly negate its ability to carry loads in the vicinity of the cut and reduce the load carrying capacity until the development length allows the reinforcing bar to start carrying it full load.

    The layout of your cracked section isn’t clear from your description. An 8 to 10 mil (2 to 2.5 mm) crack is sizable in a water-containing structure. Fixing the existing crack with a reinforcing bar epoxied in place across the crack may be effective. However, that solution would only carry any additional load on the section (structural or volume change), as the existing loads have already created cracks. Thus, you should also address filling the crack as part of the solution. This may be with epoxy injection or swellable polyurethane grouts. You should consult with the pool design engineer for their recommendation on the best method for repair.