Chemical Comparison of Fly Ash & Portland Cement - Technical Bulletin

The table below shows typical compound analyses for two fly ashes and a natural pozzolan (Class F fly ash, Class C fly ash and Class N - Natural) and ordinary portland cement. A glance at the table reveals that the same compounds exist in fly ash and portland cement. Those of fly ash are amorphous (glassy) due to rapid cooling; those of cement are crystalline, formed by slower cooling.