No abstract

It was tested whether powdered flint is able to reach pozzolanic properties comparable to fly ash. The flint aggregates were crushed and milled to three different grain size fractions comparable to coal fly ash. The powdered flint was characterized and subsequently used as a substitute in mortar prisms. The compressive strength tests showed a potentially pozzolanic reactive behavior at 28 days of two different fine grained flint fractions. But comparable investigations after 92 days showed that the typical subsequent hardening of pozzolanic materials could not be obtained. The strength was much lower than the strength of comparable specimens with fly ash. Further, thermogravimetric analysis of the tested mortars after 28 days showed a much lower portlandite consumption compared with mortar with fly ash. The study concludes that at least the examined powdered flint with high density does not have the opportunity to replace coal fly ash as pozzolan.