Shotcrete is just a placement method for concrete. Shotcrete placement with proper materials and application techniques should provide monolithic concrete with a 28-day compressive strength of at least 4000 lb/in2 (28 MPa). Thus, any systems that work in concrete should be fine. Either mechanically-fixed or epoxy-set anchors are commonly used in concrete. You should consult with the anchor suppliers for the size and type of anchor appropriate for your specific application.
The Value of VR Training for Today’s Shotcrete Nozzlemen
Recruiting, training, and retaining skilled shotcrete nozzlemen is mission-critical for a company’s success. Virtual, immersive training offers an effective, engaging mode of learning that supports the modern trainee. For beginning nozzlemen, virtual reality training gives them a safe, repeatable experience that can be completed in a classroom, free of job costs. Practice without cost or risk also helps improve job performance and satisfaction. These disruptive virtual reality (VR) technologies can provide safe, hands-on learning experiences without the field costs associated with hands-on training. Virtual learning is also valuable in today’s socially distanced world with its shifting remote learning requirements. Interactive digital tools will deliver meaningful, adaptive training for skilled trades now and in the future. Though some level of hand nozzling experience is still needed the best nozzlemen will be trained, in part, using virtual reality.
Encapsulation of Reinforcement in Tunnel Shotcrete Final Linings
Using shotcrete for the placement of concrete for tunnel final linings is becoming more common. In the past the use of shotcrete final linings was typically limited to non-public or emergency egress areas, however, shotcrete is being used more and more in public areas. The use of shotcrete is typically an attractive alternative to form-and-pour final lining installation where formwork costs are high or technically challenging, pose a scheduling issue, or where labor rates are very high. Typical examples for successful use of shotcrete final linings are complex lining geometries, intersecting or merging tunnels, widenings, short tunnels without sufficient repeating utilization of the forms, or underground systems where formwork would block passing traffic.
Mechanical Application of Shotcrete in Underground Construction
The manual hand application of shotcrete began over 100 years ago and continues today in a wide range of applications and projects. To provide a proper distance of the shotcrete nozzle tip to the underground surface wall, surface receiving shotcrete or ‘substrate,’ the hand application of shotcrete in larger diameter underground structures required the nozzlemen to operate from a man-lift or similar equipment. Working from elevated platforms and the close proximity of the nozzleman to the substrate added safety challenges to projects. Thus, as more underground projects started to use the wetmix shotcrete process, spraying shotcrete with mechanical arms began to address these safety concerns.
Site-Specific Mine Site Safety in North America
Show me a person who tells you that safety on a mine site is just plain common sense, and I’ll show you someone who doesn’t understand mine safety completely. Mine safety is not simply common sense. It is that, and a whole lot more. Most mines have their own set of mine-specific regulations and rules. Nearly all mines, in Canada, the USA, and Mexico, are required by law, to follow government-mandated requirements such as U.S. Department of Labor- Mining Health & Safety Administration (MSHA) and/or the Occupational Safety & Health Administration (OSHA). Canada and Mexico have their government agencies governing mining as well. Even with strict government regulations, most mines have safety regulations specific to each individual mine. Anyone who desires to visit a mine site needs to accept one thing- whatever the rules and regulations are for a particular mine- these regulations are serious business and are meant to be enforced.
Safety in Shotcrete Application in Underground Construction
Because of its durability, strength, and flexibility in application, shotcrete is often used for the construction and stabilization of tunnels and other underground structures. The fact that tunneling involves general construction risks as well as tunnel specific environmental risks, makes this type of application potentially quite dangerous, and must be treated with caution. Risks cannot be eliminated, but we can implement measures to lower the risk.
Outstanding Underground Project
Project Name:
Courthouse Commons Tunnel
Location:
San Diego, CA
Shotcrete Contractor:
Atkinson Construction
Architect/Engineer:
McMillen Jacobs Associates
Material Supplier/Manufacturer:
The Quikrete Company
Equipment Manufacturer:
Normet
General Contractor:
Holland Partner Group
Project Owner:
Holland Partner Group
Outstanding International Project
Project Name:
M4-M5 Link Tunnels
Location:
Sydney, Australia
Shotcrete Contractor:
Acciona Bouygues Samsung Joint Venture
Architect/Engineer:
Jacobs Aurecon Joint Venture
Material Supplier/Manufacturer:
Bekaert
Equipment Manufacturer:
Normet Asia Pacific Ltd
General Contractor:
Acciona Bouygues Samsung Joint Venture
Project Owner:
Jacobs Engineering Group
ASA Real-Time In-Situ Article
Construction of sprayed concrete lining (SCL) ground support across the world utilizes the construct, verify and rework cycle. This methodology typically requires survey verification of the as-built result against design for each stage of the ground support installation. However, processing and analyzing the measurement data is a time consuming and often intensive manual process.
Shotcrete Incorporated into ACI 318-19 Building Code
Since the shotcrete process originated well over 100 years ago, improvements in materials, equipment, and placement techniques have enabled it to become a well-proven method for structural concrete placement. The efficiency and flexibility of shotcrete have been used to great advantage in sizable structural projects, as the high-velocity impact inherent in the process provides the compaction needed to turn low-slump concrete into freestanding vertical and overhead placements with minimal formwork.