Toolbox Talk – Shotcrete

Welcome to this weeks Toolbox Talk – Shotcrete. A technique involving projecting concrete at high velocity onto vertical or overhead surfaces, is widely employed in construction. This method utilises the impact generated during application to consolidate the concrete. While shotcrete exhibits similar hardened properties to conventional cast-in-place concrete, its unique placement process fosters an exceptional bond with most substrates. It boasts rapid or instantaneous setting capabilities, making it particularly advantageous for intricate forms or shapes.

Benefits

• The shotcrete process demands less formwork than conventional concrete placement methods, rendering it more economical.
• Shotcrete finds extensive application in both new construction and repair projects, proving suitable for curved and thin elements alike.
• Its versatility and efficiency make it a valuable asset in the realm of construction.

There are two ways that concrete can be placed using this method:

• Dry-mix, or “gunite,” places the dry concrete ingredients (gravel, sand, and Portland cement) in a hopper and carries them with compressed air through a hose to the nozzle. Here, water is added, and workers spray the concrete mixture onto the surface that has been prepared. This is a topic for another time.
• Wet-mix, or “shotcrete,” places ready-mixed concrete (sometimes with reinforcing fiber added) into a hopper and pumps the concrete through a hose to the nozzle. Here, compressed air is injected, and a worker sprays the concrete onto the surface that has been prepared. This is the more common process in the late 20th and 21st centuries.

Hazards

1. Over excavated area can lead to soil collapse.
2. Noise induced hearing loss as the Compressor and Furukawa generates above 85Db noise.
3. Nip and Pinch points when fitting hammers or rods and couplings.
4. Coupling can detach and fall, if the mast is horizontal it could fall on someone`s foot if the mast is vertical it can fall on any body part of a person from a height which could cause extensive injury.
5. When Shotcreting the rebound ‘’grout back splashing from the face of the wall’’ can cause superficial wounds if proper PPE is not worn.
6. Back strain when not using the correct posture and buddy system to move hammers and rods.
7. Drilling for heights via a Man cage and Cherry Picker / Telehandler comes with various additional risks
8. Couplings can detach while performing shotcrete and could result in extensive injury
9. High pressure is used, which could lead to pipes bursting and grout spraying onto workers at a high-pressure rate.
10. Labour intensive – moving pipes, carrying and inserting rods and doing repetitive work

Project specific hazards are identified at the start of each project and managed accordingly the above is general.

Download the full Toolbox Talk document on Shotcrete below: