What is Slag Cement?
Using slag cement makes concrete more consistent, resistant to aggressive chemicals and less permeable. Slag cement has been used in concrete projects in the United States for over a century. Over the years, modern designers have been able to improve durability to produce the lowest life-cycle and maintenance costs possible. These long-term performance enhancements have allowed for a reduced environmental footprint of concrete while ensuring improved performance and increased durability.
Slag cement can be used in a wide variety of commercial and architectural applications. Slag cement should be used as a pound for pound replacement for a portion of the Portland cement in a concrete mixture. Depending on the desired properties or application, various replacement levels can be used. The table below lists suggested levels of replacement for some common applications. Source: Slag Cement Assocation
| Concrete Application | Slag Cement |
| Concrete Paving | 25-50% |
| Exterior flatwork not exposed to deicer-salts | 25-50% |
| Exterior flatwork exposed to deicer salts with w/ cm = 0.45 | 25-50% |
| Interior Flatwork | 25-50% |
| Basement Floors | 25-50% |
| Footings | 30-65% |
| Walls & Columns | 25-50% |
| Tilt-Up Panels | 25-50% |
| Pre-Stressed Concrete | 20-50% |
| Pre-Cast Concrete | 20-50% |
| Concrete Blocks | 20-50% |
| Concrete Pavers | 20-50% |
| High Strength | 25-50% |
| ASR Mitigation | 25-70% |
| Sulfate Resistance | |
| Type 1 Equivalence | 25-50% |
| Type V Equivalence | 50-65% |
| Lower Permeability | 25-65% |
| Mass Concrete | 50-80% |
Added Value, Better Performance
- Lower Permeability
- Decreases drying Shrinkage
- Mitigates ASR
- Lowers embodied carbon emissions
- Improves Workability
- Higher long-term compressive strength
- Increased sulfate protection
- Superior finishing qualities
- Reduce water demand
- Improved durability and resilience
Compressive Strength Comparison
Portland Cement vs. 25 and 50% Slag Cement Mix Designs.
Compressive strength will vary depending on the mix design, with 100% Portland cement providing higher early strength at 7 days. However, incorporating 25% or 50% slag cement can result in greater long-term strength at 28 days, offering both performance and sustainability advantages.
Set Time
Set times will vary based on application, but utilizing more sustainable materials can mean the concrete may behave differently. It’s important to understand and plan for these adjustments with all teams involved so that schedules are not negatively impacted without warning.