In this paper, the effect of fly ash percentage of different fields or hoppers on the compressive strength of cement paste with and without superplasticizer has been studied. The accelerated pozzolanic activity of fly ash of each field and their blending has been evaluated with and without superplasticizer. The pozzolanic activity increases from field I to V as expected, the noticeable observation is that with the use of superplasticizer, the pozzolanic activity of the first field is comparable to control value of 340 kg/cm². Further, the pozzolanic activity of blended fly ash of first field with fly ash of other fields, the pozzolanic reactivity is comparable to control value. In case of 50-50 blending of first field and second field fly ash the pozzolanic activity is approx 7% more than control