Development of Engineered Cementitious Composites (ECCs) Incorporating Iron Ore Tailings as Eco-Friendly Aggregates

In this study, iron ore tailings (IOTs) are used as aggregates to prepare iron-ore-tailing-engineered cementitious composites (IOT-ECCs) to achieve clean production. Some mechanical indexes, such as compressive strength (fcu), four-point flexural strength (ff), axial compressive strength (fc), deformation properties, flexural toughness, and stress–strain behavior, are studied. The mass loss, fcu loss, relative dynamic modulus elasticity (RDEM), and deterioration mechanism after the sulfate freeze–thaw (F-T) cycle are discussed in detail. In addition, pore structure analysis is performed using nuclear magnetic resonance (NMR), while a scanning electron microscope (SEM) is utilized to study the micro-morphology. The results showed that under the 20–80% IOT replacement ratio, IOT-ECCs exhibited improvements in their mechanical properties, pore structure, and resistance to sulfate freeze–thaw (F-T). The most notable mechanical properties and sulfate F-T resistance were demonstrated by the IOT-ECC with 40% IOTs (namely, IOT40-P2.0). Meanwhile, IOT40-P2.0 exhibited good pore structure as well as the bonding interface of the PF and the matrix. The pore structure and compactness of the matrix of IOT-ECCs gradually deteriorated as the F-T cycle increased. The research results will promote the application of IOTs in ECCs.

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