Dry Spray/Gunite

RIX is a market leader in dry spray application. Dry spray shotcrete, or dry shot, was first introduced in the USA in 1907, where it remains commonly known as gunite. In the early 1950s, wet shotcrete was developed and introduced commercially.

Dry spray is pumped in its dry form by high pressure air and mixed at the nozzle with water. Dry spray nozzlemen require an extra level of knowledge and care as they control the quality of the shotcrete mixed at the nozzle. Dry spray is best suited and more commonly used in the following applications:

  • Projects that require sculpting or carving
  • Simulated rock or blocks (mock rock)
  • Tele-remote shaft lining
  • Smaller quantities (<20m³)
  • Application via rope access
  • Rock simulation (mock rock)
  • Longer pumping distances, limited access or remote areas

Main differences of dry shotcrete:

  • Requires less capital and maintenance expenditure
  • Increased labour for self-batching
  • Has smaller aggregate but generally higher rebound
  • Requires smaller and lighter delivery hoses
  • Allows longer pumping distances
  • Better suited to smaller projects and concrete repair

Above: A failing sandstone boathouse on Sydney harbour requiring urgent repair. RIX was asked to provide an economic and aesthetically similar solution. Project challenges included:

  • Limited access
  • 100m from the nearest street
  • Working at heights
  • Tidal environment

Dry spray was chosen to avoid the need for placing larger wet spray shotcrete pumps and concrete agitators on barges at high cost with limited productivity. This coupled with sculpting requirements to offer a simulated sandstone block finish meant dry spray was the perfect choice.

Centre: Boathouse on Sydney Harbour.

Left: RIX’s expert dry spray nozzleman spraying overhead in a limited access cavern, offering rock bolts, mesh and the final ground support solution.

Right: A previously unusable backyard. A carved simulated rock shotcrete retaining wall has transformed this backyard into a usable space.