The annual global production of fly ash is estimated at about 780 million tons per year and has been used successfully in the cement industry for more than 50 years, mainly as a mineral additive in Portland cement and also as a component of mixed cement. In this work, the ash reactivity from hazardous waste as supplementary cement material was evaluated. For this, the ashes reactivity in lime pastes was analyzed, centered on thermogravimetric tests as a characterization technique to determine the phases present. Part of the ashes of