Fly Ash particles are small spheres. When processed (graded) this sphere shape should not be cracked – angular shaped particles should be avoided.  To avoid this all DIRK PHOENIX Fly Ash processing projects use air for conveying as well as for classification. This is important for utilization of DIRK PHOENIX products of all grades as the maintained sphere shape reduces the water demand in concrete which also leads to improved concrete strength.

As mentioned in the chapter GRADES, smaller particles create more surface for better pozzolanic reaction and reduction of free lime which improves the sustainability of concrete.

The smaller spheres create a dense concrete as they can more easily fill the voids between the aggregates.

The classification of fly ash means extraction of a certain particle size out of a stream of mixed particles. Consequently specific size demands can not be fulfilled. To close the gap between demand and supply, rejects from the classification process are ground. This increases  the fraction of angular shape. A partial replacement of cement by ground fly ash in concrete can be seen from the table below:

The  cement industry is grinding run-off-station ash or rejects from classification together with their cement clinker. The result is a PPC  with similar features like blended OPC with ground fly ash.

Note: DIRK PHOENIX do not provide ground Fly Ash to maintain the outstanding quality introduced by Georg Dirk in to India.