Gunite

What is Gunite?

Gunite is a construction method where dry concrete mixture is pneumatically applied at high velocity through a specialized spray gun. The water is added at the nozzle, creating a dense, strong concrete structure that bonds exceptionally well to surfaces.

Gunite is most commonly used in swimming pool construction but also serves structural applications in tunneling, slope stabilization, and repair work.

Gunite vs. Shotcrete

Gunite (Dry-Mix Process)

Dry cement and aggregate mixed at job site
Water added at spray nozzle
Better quality control over water content
Preferred for swimming pools and precision work

Shotcrete (Wet-Mix Process)

Pre-mixed concrete pumped through hose
All ingredients mixed before application
Faster application for large areas
Common for structural and commercial projects

Swimming Pool Applications

Pool Shell Construction

Gunite creates the structural foundation of concrete pools:

Applied over rebar framework
Forms curved and complex shapes easily
Provides watertight, durable shell
Allows for custom pool designs

Typical Pool Gunite Process

Excavation: Dig pool to specified dimensions
Plumbing/Electrical: Install rough-in systems
Rebar Installation: Steel reinforcement framework
Gunite Application: Spray concrete mixture at high pressure
Curing: Allow concrete to strengthen (7-28 days)
Finishing: Apply plaster, tile, or other surface materials

Advantages of Gunite

Structural Benefits

High Strength: Compressive strength often exceeds 4,000 PSI Excellent Bond: Adheres strongly to existing surfaces Minimal Shrinkage: Dense application reduces cracking Durability: Long-lasting structural integrity

Design Flexibility

Custom Shapes: Can form any pool shape or size Integrated Features: Built-in spas, steps, benches Curved Surfaces: Smooth transitions and organic shapes Structural Integration: Combines with decking and landscape features

Gunite Application Process

Equipment Required

Gunite Machine: Mixes and delivers dry materials
Air Compressor: Provides pneumatic pressure
Spray Nozzle: Controls water addition and application
Hoses: Transport materials to application point

Crew Requirements

Typically requires 3-5 person crew:

Nozzle Operator: Controls gunite application
Ground Support: Manages hoses and materials
Finisher: Shapes and smooths applied gunite
Loader: Feeds materials into machine

Quality Control Factors

Mix Design

Cement Content: Typically 600-700 lbs per cubic yard Aggregate Size: Usually 3/8" maximum size Water-Cement Ratio: Critical for strength (typically 0.35-0.45) Additives: Accelerators, plasticizers as needed

Application Standards

Thickness: Pool shells typically 6-8 inches thick Compaction: Must achieve proper density during application Temperature: Avoid application in extreme temperatures Curing: Proper moisture retention for strength development

Cost Considerations

Material Costs

Concrete mix: $100-$150 per cubic yard
Labor: $8-$15 per square foot of surface area
Equipment: Daily rental $500-$1,500 depending on size

Project Factors

Pool Size: Larger pools have lower per-square-foot costs Access: Difficult access increases labor costs Complexity: Custom shapes and features add cost Site Conditions: Rock, utilities, slopes affect pricing

Common Applications Beyond Pools

Structural Repair

Tunnel lining and repair
Bridge deck rehabilitation
Foundation underpinning
Retaining wall construction

Architectural Features

Artificial rock formations
Sculptural elements
Curved architectural surfaces
Theme park construction

Quality Issues and Solutions

Common Problems

Rebound: Material bouncing off surface (5-15% normal) Shadowing: Areas with insufficient coverage Honeycombing: Voids in finished surface Cold Joints: Poor bonding between application layers

Best Practices

Maintain consistent application speed
Remove rebound material promptly
Keep surfaces damp before application
Work continuously to avoid cold joints
Use experienced, certified applicators

Features

Core Features

Apps & Integrations