A brief presentation is made on the problem of fly ash from sugar production, which can be transformed into pozzolan through physical, thermal, chemical or mixed activation, and then used as a chemical corrector and additive for the production of Portland cement. The conversion of the ash into pozzolans is carried out with hydrothermal processes that include repetitive actions of incubation, filtration and drying, for which an alkali solution is used at high temperatures, where compounds such as zeolites are formed from the amorphous aluminosilicates present, being necessary in some cases to adjust the Si/Al ratio to produce the desired type of pozzolan. It is concluded that the use of fly ash, as a chemical corrector in the raw clinker mix, depends on the purity of the limestone and the evaluation of the chemical balance of the mix.