NUCLEAR AND POZZOLANIC FACTORS IN STRENGTH DEVELOPMENT OF CLASS F FLY ASH CONCRETE

The paper presents a new model for the analysis of strength development of a Class F fly ash concrete. The analysis shows that the contribution of that fly ash to strength development is dependent on 2 parameters of the mix: nucleation and pozzolanic factors. These parameters fully conform to the effects of proportioning the fly ash mixes. The parameters were adequate to account for the strength development of fly ash concrete. The results show that the methods for the design of fly ash concrete based on a single parameter like the 'cementing efficiency' may not be capable of modeling the strength developments accurately. The results show that the strength contribution up to 28 days can be broadly attributed to nucleation factor after 28 days to pozzolanic factor. The onset of the pozzolanic reaction depends on the fly ash/cementitious ratio of the mix.