What is guniting?
Guniting is a way of applying cement mortar with compressed air. A dry mix of cement and fine sand is blown through a hose to a nozzle, where water is added, and the mortar is shot onto the surface at high speed. The impact compacts it into a dense layer that bonds firmly to the concrete or masonry behind it. Because it can be built up on walls and overhead surfaces without shuttering, guniting is widely used to repair, strengthen and waterproof existing structures.
You will also hear it called gunite, sprayed concrete or shotcrete. Strictly, guniting is the dry-mix process with fine aggregate, while shotcrete usually means sprayed concrete with coarser aggregate, but on Indian sites the terms are often used for the same work.
Guniting or ordinary plaster?
Plaster is applied by hand and depends on the mason pressing it on. Gunite is placed by air pressure, so it is denser, less porous and better bonded. That is why it is chosen for water-retaining structures and for concrete that has to carry load again after repair.
When guniting is the right fix
- Spalled or corroded concrete
- Leaking water tanks and reservoirs
- Basement and retaining walls
- Drains, culverts and tunnels
- Slope and embankment protection
- Strengthening old masonry
How guniting work is done
- Surface preparationLoose concrete removed, reinforcement cleaned and treated.
- Mesh fixingWeld mesh anchored to the surface where specified.
- GunitingMortar sprayed in layers to the required thickness.
- Curing and finishingCured to specification, then finished or coated as needed.
