Concrete sustainability with very high amount of fly ash and slag

Resumo

This article approaches concrete mix designs where cement is replaced by high amounts of slag and fly ash, with the purpose of turning it into a more sustainable construction material, that is, an authentic green concrete. Mix proportions with fly ash, ground-blasted furnace slag, and Portland cement were studied in binary and ternary mixtures for compressive strength levels of 40 MPa and 55 MPa. The replacement of cement with mineral additions ranged from 50% to 90% in mass. Mean decreases of 55% in the energy consumption, 78% in the CO2 emissions, and 5% in the cost of the concrete m³, plus an increase of 40% in the mean index of durability were obtained, all of which compared to the 40-MPa reference concrete. This study attests the technical, economical and environmental potentialities for the use of concrete mixtures with until 90% of fly ash.