Pulverised Fuel Ash (PFA)

Summary

Technical Information

Fly ash is a pozzolan and a waste product of power station fuel furnaces; therefore it is more environmentally friendly and typically cheaper to use than Portland cement.

Some properties of fly ash against Portland cement:

• Increased workability with same water to binder ratio.
• Lower early strength – fly ash takes longer to hydrate properly than Portland, which means that development of full design strength can take longer than an equivalent mix containing CEM 1.
• Similar Ultimate Strength – the long term strength of concrete containing fly ash is usually similar to the long term strength of concrete with 100% Portland cement.
• Reduced bleeding.
• More air entraining admixture required to achieve similar air content.
• Lower heat of hydration, meaning set can be delayed.  This can be an issue when casting slabs in colder climates, but beneficial when construction warmer temperatures as the concrete remains workable for longer.
• Can lower the chance of a damaging alkali-silica reaction.

Please share this definition:

1. Categories
   • A (26)
   • B (13)
   • C (45)
   • D (25)
   • E (14)
   • Europe (1)
   • F (32)
   • G (5)
   • H (6)
   • I (5)
   • J (10)
   • L (18)
   • M (10)
   • O (3)
   • P (47)
   • R (17)
   • S (41)
   • T (19)
   • U (2)
   • V (9)
   • W (15)
   • Y (1)