Development of green engineered cementitious composites using iron ore tailings as aggregates

• Iron ore tailings (IOTs) were used as aggregates to prepare green ECC.
• Influences of IOTs size on fresh properties of ECC mortar were investigated.
• Influences of IOTs size on tensile properties of ECC were studied.
• The mechanical properties of ECC with IOTs are comparable to that with silica sand.

Micro-silica sand is often used as fine aggregate in the production of Engineered Cementitious Composites (ECC), which is a class of ultra-ductile fiber-reinforced cement-based structural materials. However, high cost and limited availability of micro-silica sand creates an obstacle for widespread application of ECC in civil infrastructure. To overcome this limitation, the present study explores the feasibility of using iron ore tailings (IOTs) as cheaper and more environmentally friendly alternative aggregates without sacrificing the ductile mechanical performance of standard ECC. Influences of the size of IOTs on plastic viscosity of fresh ECC mortar, and on tensile properties and fiber dispersion in composites were experimentally investigated. At two levels of fly ash/cement ratio, performance of ECC with IOTs under direct tension and compression was investigated. The results show that ECC with IOTs as aggregates can attain tensile and compressive properties comparable to ECC with typically-used micro-silica sand, provided that the size of IOTs used is in the appropriate range which facilitates good fiber dispersion. Thus, the feasibility of using industrial solid waste-iron ore tailings as aggregates in the development of highly ductile and green ECC was established.