EN 450 Fly Ash
EN 450 Fly Ash (formerly known as Part 1 PFA) can be used as a replacement for Portland cement in virtually any concrete application. For general purpose applications, concrete containing 25%-40% PFA is most suitable.
ScotAsh's EN 450 fly ash is specially selected at Longannet Power Station. Real time carbon analysers measure the Loss-on-ignition (LOI) of the PFA as it is carried out in the flue gases to ensure that the material selected has an LOI of less than 7%.
Quality
EN450 can be classified into different finenesses:
EN450 Category S fly ash restricts the fineness of the fly ash to a maximum of 12.0% passing the 45 micron sieve, during classification and limits the LOI to a maximum of 7%. These requirements ensure the optimum water reducing, reactivity and consistency properties are achieved within the concrete mix.
EN 450 'Category N fly ash is permitted by BS EN206 and BS 8500, offering a wider range of fineness than with Category S fly ash. The supplier nominates a target fineness value of 0-40% passing the 45 micron sieve. The fly ash supplied must not exceed plus or minus 10% of this target value. Again the LOI
limit is 7%.
Both category S and N BS EN450 fly ashes are classed as Type II additions - they count towards the total cementitious content of the concrete.
Fly ash can also be used in concrete as inert filler or an aggregate - known as a Type I addition
Uses and Benefits
EN450 fly ash in concrete offers improved rheology, reduced bleeding and uses less water than Portland cement concretes. It also improves pumpability and gives an excellent finish.
Recommended Construction Uses of PFA-based Concretes
Excellent |
Potentially alkali-reactive aggregates |
Good |
Air-entrained concrete |
Use with care |
In high early strength applications unless hydration is accelerated by increasing temperature |
Download EN 450 Fly Ash product information leaflet (coming soon)
