What is Fly Ash? (Green Concrete Additive)

What is Fly Ash? (Green Concrete Additive)

Fly ash is a coal combustion byproduct used to replace cement in concrete. It improves workability and reduces heat during curing. It's considered a "green" additive because it reuses waste material. Understanding fly ash helps you understand modern concrete mixes.

What is Fly Ash?

Fly ash is:

• Coal byproduct: Fine particles from coal combustion
• Cement replacement: Can replace up to 20-30% of cement
• Pozzolanic material: Reacts with calcium hydroxide
• Waste product: Reuses industrial waste

Benefits of Fly Ash

Improves Workability:

• Makes concrete easier to work
• Improves flowability
• Better finishability

Reduces Heat:

• Less heat during curing
• Reduces thermal cracking
• Important for large pours

Environmental Benefits:

• Reuses waste material
• Reduces cement use
• Reduces CO2 emissions

How It Works

Fly ash reacts with calcium hydroxide:

1. Cement hydration: Cement creates calcium hydroxide
2. Fly ash reaction: Fly ash reacts with calcium hydroxide
3. Forms cementitious compounds: Creates additional strength
4. Slower strength gain: Strength develops more slowly

The Bottom Line

Fly ash is a coal combustion byproduct used to replace cement. It improves workability and reduces heat during curing. It's considered "green" because it reuses waste material. Fly ash is commonly used in modern concrete mixes to improve performance and reduce environmental impact.

Need concrete with fly ash? Contact Local Concrete Contractor. We use modern mix designs including fly ash when appropriate for your project.