Shotcrete

Shotcreting is the process of applying concrete by the use of a nozzle in which compressed air is introduced to the material flow. Shotcreting is usually classified as a wet mix or dry mix and the type of aggregate used, coarse or fine.

Wet mix shotcrete - Shotcrete in which all of the ingredients including water, are mixed before introduction in to the delivery hose (ACI-506R4).

Dry mix shotcrete - The cement-aggregate mixture is fed into a special mechanical feeder or gun called delivery equipment, which is metered by a device such as a feed wheel, rotor or feed bowl. The material is carried by compressed air through the delivery hose to nozzle body. The nozzle body is fitted inside with a water ring, through which water is introduced under pressure and mixed with the other ingredients. (ACI-506R-4) 1.6.1).

Comparison of Dry & Wet Mix

Dry Mix

  • Control over mixing water
  • Suited for light weight mixes
  • Material transported longer distance
  • Minimal material waste
  • High strengths

Wet Mix

  • Water accurately measured
  • Mixing more consistent
  • Less dust and cement loss
  • Normally less rebound
  • Greater production

Shotcrete - Metamora WWTP, Metamora, IN:

preparing the earth wall for shotcrete installation
putting up rebar
installing hydraway drainage system behind rebar
digging next level of earth wall
first level of earth wall completed
earth retention using shotcrete
finishing application of shotcrete earth retention