Spray on concrete is more than a technique — it’s a game changer in construction. Whether you’re working on infrastructure projects, residential builds, or structural repairs, shotcrete provides unmatched speed, strength, and cost efficiency.
As technology improves, expect spray on concrete to become a go-to solution for engineers and builders worldwide.
The Rise of Spray on Concrete
In the modern construction world, time, durability, and efficiency are everything.
One technique that’s rapidly gaining popularity is spray on concrete, also known as shotcrete or gunite.
Unlike traditional poured concrete, spray on concrete is applied at high velocity through a hose, bonding instantly to surfaces and eliminating much of the formwork required in conventional methods.
From tunnel lining to swimming pool construction, this method is revolutionising how we approach concrete application.
What is Spray on Concrete?
Spray on concrete is a pneumatic concrete application process where a dry or wet concrete mix is projected through a high-pressure nozzle directly onto a surface.
The process relies on compressed air, ensuring that the concrete adheres tightly and forms a dense, durable finish.
Types of Spray on Concrete
- Dry-Mix Shotcrete (Gunite)
- Dry materials are fed into the hose, and water is added at the nozzle.
- Often used in swimming pools, slope stabilisation, and repair works.
- Wet-Mix Shotcrete
- Pre-mixed concrete is pumped through the hose.
- Common in large-scale structural applications, such as tunnels and bridge reinforcement.
Advantages of Spray on Concrete
- Speed: Eliminates the need for extensive formwork, cutting project timelines.
- Durability: Dense compaction increases strength and resistance to weathering.
- Versatility: Can be applied on vertical, curved, or overhead surfaces.
- Cost Efficiency: Reduced labour and quicker completion mean lower overall costs.
- Structural Integrity: Excellent adhesion even on irregular surfaces.
- Minimal Formwork: Perfect for hard-to-reach or complex shapes.
Applications of Spray on Concrete in Construction
Spray on concrete is widely used across industries due to its adaptability:
1. Swimming Pool Construction
Gunite pools rely on dry-mix shotcrete to create smooth, waterproof shells.
2. Tunnel Lining
Wet-mix shotcrete offers high structural support in tunnelling projects.
3. Retaining Walls
Fast application makes it ideal for slope stabilisation and erosion control.
4. Concrete Repair & Restoration
Damaged bridges, walls, and facades can be quickly restored without dismantling.
5. Mining Support
Sprayed concrete stabilises mine walls, ensuring safety and durability.
Spray on Concrete Process – Step by Step
- Surface Preparation – Clean and moisten the area for better adhesion.
- Mixing – Depending on the method, prepare dry or wet mix with correct cement–aggregate ratios.
- Nozzle Application – Apply concrete at high pressure for dense compaction.
- Finishing – Smooth and shape the surface as required.
- Curing – Keep the concrete moist to achieve maximum strength.
Safety & Best Practices
- Always wear protective gear (helmets, masks, gloves).
- Maintain correct nozzle distance for uniform application.
- Ensure proper mix consistency to avoid rebound waste.
- Follow construction safety protocols to prevent accidents.
Spray on Concrete vs Traditional Poured Concrete
| Feature | Spray on Concrete | Poured Concrete |
|---|---|---|
| Speed | Much faster | Slower due to formwork |
| Formwork Required | Minimal | Extensive |
| Surface Shapes | Works on any shape | Mostly flat or simple shapes |
| Labor Cost | Lower | Higher |
| Durability | High | High (if cured properly) |
Cost Considerations
The spray on concrete cost per square foot varies depending on mix type, site access, and application area. On average:
- Dry-mix: More economical for small or medium projects.
- Wet-mix: Higher upfront cost but better for large, structural jobs.
Sustainable Construction with Spray on Concrete
This method supports sustainable building by:
- Reducing material waste (less rebound).
- Minimising formwork materials.
- Extending structure lifespan, reducing replacements.