Concrete Mix Types and Ratios
Overview of common concrete mix types, typical ratios, and use cases.
Understanding Mix Types
Concrete mixes vary by strength, workability, and durability. Typical mixes balance cement, sand, and aggregate for the intended application.
Standard Mix Ratios (by volume)
| Mix | Cement | Sand | Aggregate | Typical Use |
|---|---|---|---|---|
| 1:2:3 | 1 | 2 | 3 | Driveways, slabs, general purpose |
| 1:2:4 | 1 | 2 | 4 | Footings, sidewalks |
| 1:3:3 | 1 | 3 | 3 | Higher workability applications |
| 1:1.5:3 | 1 | 1.5 | 3 | Higher strength (consult spec) |
Common Mix Types
Normal Strength
Definition: Typical mixes around 20–35 MPa (3000–5000 PSI).
Use: Slabs, driveways, walkways, residential footings.
Example: 1:2:3 for a 4 inch slab.
High Strength
Definition: Designed for > 40 MPa (6000+ PSI) applications.
Use: Structural elements requiring high performance.
Example: Lower w/c ratio, admixtures as specified.
Lean Mix
Definition: Lower cement content; economical but lower strength.
Use: Subbase, blinding layers.
Example: 1:3:6 (verify with engineer).
Specialized Mixes
Air-Entrained
Improved freeze-thaw durability
Slight reduction in strength
Common in cold climates
Fiber-Reinforced
Reduces shrinkage cracking
Improves toughness
Fibers: steel, polypropylene, glass
Key Considerations
Water-Cement Ratio
Lower w/c increases strength but reduces workability.
Aggregate Size
Affects finish and pumpability; match to element thickness.
Admixtures
Set-time and workability modifiers; follow supplier guidance.
Common Mix Mistakes
- Using volume instead of weight where spec requires weights
- Adding water on site without adjusting for strength
- Ignoring local code or engineer specifications
Ordering Quantities
Order concrete in cubic yards (US) or cubic meters (metric), and include an appropriate waste factor.
- Add 5–10% for most pours
- Small jobs may incur short-load charges
- Coordinate delivery timing with crew readiness
For structural or critical applications, follow engineered mix designs.