Mechanochemical activation of iron ore tailing-based ternary supplementary cementitious materials

Abstract

• Both mechanical and mechanochemical activation methods are effective to improve the chemical activity of iron ore tailings. • Less surface binding energy reflects less crystallinity and higher reactivity. • Ternary IOTs-based SCMs resulted in the comressive strength enhancement and pore structure refinement. The increasing concern for decarbonization calls for sustainable construction materials since carbon dioxide emissions from cement industries account for 8% of the total emissions. Incorporating municipal solid waste into concrete as supplementary cementitious materials (SCMs) is one of the fundamental ways to achieve urban sustainability. Iron ore tailings (IOTs), a type of mining waste from the beneficiation process of iron ore concentrates, can be used as SCMs via various activation methods. While activation of IOTs alone has been a topic of intensive research for years, there is a lack of comprehensive study on mechanical-chemical coupling activation of IOT-based ternary SCMs systems (IOT, fly ash, and ground granulated blast furnace slag) considering the utilization of other industrial by-products and waste. This study investigates the effect of grinding time and chemical activators on the properties of IOT-based ternary SCMs. XRD, XPS, DTA-TG, compression tests, Mercury intrusion porosimetry, and SEM were employed to investigate the crystal structure and crystallinity of IOTs, surface energy, mechanical properties, pore structure, and morphology of the hydration products of the ternary system. The results obtained from this study revealed that an increase in grinding time and chemical activators improved the activity index of IOTs-based ternary SCMs. In addition, Na 2 SiO 3 contributed the most to the activity index among the three types of activators. This work has expanded the possibility of utilizing IOT-based ternary SCMs via proper activation methods for sustainable construction.