Results
At 28 days, tailings concrete reached 36.95 MPa compressive strength versus 33.12 MPa for the control. Split tensile strength was lower: 2.82 versus 3.36 MPa. Slump was 20 versus 80 mm.
How it was tested
Extension Hill tailings replaced all fine and coarse aggregate. The cement:fine:coarse ratio was 1:2:3, with water/cement of 0.5 and a 40 MPa design target. Mixing took place at 25–30°C. Three specimens per curing age were averaged for strength tests.
Workability and durability
The authors classed the tailings mix as having low workability. They linked its lower tensile strength to higher fines content and water demand. Their acid-resistance and alkalinity assessment used pH measurements on ground mortar mixed with distilled water, only for the tailings concrete. Values of 11.8–12.5 led them to infer low acid-attack and corrosion potential.
Authors’ conclusions
The authors proposed tailings as an alternative aggregate and discussed possible environmental and economic benefits.
Original sources
Francis Atta Kuranchie; Sanjay Kumar Shukla; Daryoush Habibi; Alireza Mohyeddin (2015). Utilisation of iron ore tailings as aggregates in concrete.