Admixture

Admixtures are chemical additives used to modify concrete properties like setting time, workability, strength, or durability. Added in small quantities (typically 0.1-2% by weight of cement), admixtures can significantly improve performance or allow concrete to be used in challenging conditions.

Why It Matters

Admixtures solve specific problems. Need to pour in freezing weather? Accelerators speed setting. Working in summer heat? Retarders slow setting. Poor freeze-thaw resistance? Air entrainment adds protection. Each admixture addresses a concrete limitation, often at minimal cost compared to alternative solutions.

For DIY work, the most common admixtures are air entraining agents (for freeze-thaw climates) and water reducers (for easier placement). Ready-mix suppliers routinely add these based on season and application—you just need to specify requirements when ordering.

Technical Details

Major admixture categories:

• Air-entraining agents: Create microscopic air bubbles for freeze-thaw resistance
• Water reducers: Improve workability without adding water, or reduce water while maintaining slump
• Accelerators: Speed setting time for cold weather or fast-track projects
• Retarders: Slow setting in hot weather or for long haul times
• Superplasticizers: Dramatically increase slump for flowable concrete
• Corrosion inhibitors: Protect reinforcing steel in harsh environments

Most admixtures are proprietary formulations. Following manufacturer dosage recommendations is critical—overdosing can have severe negative effects like flash setting, excessive air content, or strength loss.

Related Terms

• Air Entrainment - Specific admixture type for freeze-thaw protection
• Water Reducer - Admixture to improve workability
• Accelerator - Admixture to speed setting

Learn More

• Types of Concrete - Different mixes and their uses
• How to Mix Concrete - Proper mixing procedures
• Concrete Calculator - Calculate your project needs