The fly ash produced at the power stations of the Ptolemais region in Northern Greece is rich in Ca due to the origin of the lignite burned and as a consequence it is characterized as a class C fly ash according to ASTM C 618. Because of the high Ca content its use in the concrete production and the production of concrete based products is restricted in Greece and only 10% of the produced fly ash is used for the production of cement. The remaining amount is deposited in mines causing environmental and financial concern.

In this paper a research was conducted in order to examine the possibilities of the Greek fly ash utilization in other applications than the cement production such as the production of paving blocks from concrete containing fly ash. For this reason paving blocks were produced from concrete including diverse proportions of fly ash which came from the Ptolemais Thermal Power Station. The aforementioned products were produced in the frame of the project ‘k-clusters: development of new products with use of fly ash from Western Macedonia’. The qualitative characteristics of the produced products were investigated as well as their mechanical properties, characteristics which were directly correlated with the properties and the proportion of the fly ash used for cement replacement