Applications
Shotcrete / Sprayed Concrete
Sprayed concrete or shotcreting is a name given to high performance concrete or mortar, which is sprayed pneumatically or through a hose onto a backing surface. For nearly a century, shotcreting has been an acceptable way of placing cementitious material in a variety of applications. It is the force of this spraying action that leads to the compaction of the concrete or mortar, which then forms layers of concrete to the required thickness.
Potential Problems
Because of the high velocity of the impacting jet, not all the concrete projected on the surface remains in position; with some material rebounding. It has been quoted that rebound can waste 40% or more of sprayed concrete applied in a project.
Rebound material consists of the coarsest particles in the mix, so that the shotcrete in situ is richer than would be expected from the mix proportions batched. This may lead to slightly increased shrinkage.
Another problem of sprayed concrete is plastic shrinkage cracking. This is due to the low water/cement ratio of the concrete.
Features and Benefits
- Improved resistance to plastic shrinkage cracks
- Improved bond
- Improved impact resistance
- Improved abrasion resistance
- Improved freeze / thaw resistance
- Reduced rebound
- Reduced permeability
- Reduces wastage
- Reduces construction time
- Reduced labour costs
- Fibres will not rust or corrode
- Provides a 3-Dimensional secondary reinforcement system