Fly Ash in East Tennessee

1
Fly Ash in East Tennessee

• Joe Sponcia
• Southeastern Fly Ash Co.

2
What Is Fly Ash?

• Fly Ash is one of the worlds most commonly used
  pozzolans.
• Pozzolans are siliceous or siliceous/aluminous
  materials which, when mixed with lime and water,
  form cementitious compounds.
• Formed from non-combustible minerals found in
  coal.
• Nearly 80 of fly ash produced in U.S. is being
  wasted in disposal areas.

3
Chemical Interaction of Fly Ash with
Concrete-Making Materials

• When Portland cement hydrates, calcium hydroxide
  is formed.
• Approximately 20 of the weight of Portland
  cement is converted to calcium hydroxide
• Does not strengthen concrete.
• Calcium hydroxide is soluble in water and may be
  removed by leaching action.
• When fly ash is employed, hydrated lime combines
  with fly ash to form a stable cementitious
  compound.
• Helps strengthen concrete.

4
Typical Chemistry

• Portland Cement Fly Ash
• 21.95 Silica 52.8
• 5.1 Alumina 22.3
• 63.8 Lime trace
• 2.4 Iron 9.2
• 2.4 Sulphur 0.7
• 2.7 Magnesia 0.2
• 0.5 Alkalines 0.5
• 1.2 LOI 3.7
• 3.15 Specific Gravity 2.30

5
Mechanical Interaction of Fly Ash with
Concrete-Making Materials

• Fly Ash particles act as ball bearings.
• Fine aggregate gradation and texture determine
  the amount of water reduction.
• Fly Ash can give 1-3 gallon water reduction per
  cubic yard.

6
Typical Concrete Mix Designs

• 3000 PSI w/ Fly Ash
• Cement 350 (lbs.)
• Fly Ash 150
• Coarse Agg. 1750
• Fine Agg. 1370
• Water 32 gallons
• Air 5

• 3000 PSI w/o Fly Ash
• Cement 440 (lbs.)
• Coarse Agg. 1750
• Fine Agg. 1460
• Water 32 gallons
• Air 5

7
Typical Concrete Mix Designs

• 4000 PSI w/ Fly Ash
• Cement 420 (lbs.)
• Fly Ash 150
• Coarse Agg. 1750
• Fine Agg. 1320
• Water 32 gallons
• Air 5

• 4000 PSI w/o Fly Ash
• Cement 540(lbs.)
• Coarse Agg. 1750
• Fine Agg. 1390
• Water 32 gallons
• Air 5

8
Technical Advantages of Fly Ash in Plastic Ready
Mixed Concrete

• Reduced Water Requirement
• Increases Workability
• Reduces Bleeding
• Reduces Segregation
• Reduces Heat of Hydration

9
Technical Advantages of Fly Ash in Hardened Ready
Mixed Concrete

• Reduces Drying Shrinkage
• Improves Water Tightness in Concrete
• Reduces Alkali-Silica Reactivity in Concrete
• Improves Resistance of Sulfate and Acid Attack
• Long Term Strength Gain