THE EFFECT OF FLY ASH/ALKALINE ACTIVATOR RATIO IN CLASS F FLY ASH BASED GEOPOLYMERS

This study focused on the effect of fly ash/alkaline activator ratio and Na2SiO3/NaOH ratio in class F based geopolymers. The objective of this study is to observe the variation of the compressive strength of the final product depending the solid/liquid ratio. In order to form the geopolymer, various parameters were changed during the geopolymerisation process. The fly ash/alkaline activator ratio studied was: 1.5; 2.0; 2.5. The geopolymeric pasta was heated up to 400 °C, 600 °C and 800 °C. After heating the compressive value of geopolymer, with the fly ash and alkaline activator ratio equal to 2 and Na2SiO3/NaOH ratio of 2.5, decreased with approximative 40 MPa comparative with the value of the sample obtained from the same composition dried for 7 days at normal temperatur