PREPARATIONS OF COMPOSITE CONCRETES USING IRON ORE TAILINGS AS FINE AGGREGATES AND THEIR MECHANICAL BEHAVIOR

摘要

Experiments were conducted to determine the utilizability of iron ore tailings from Lingxiang town near Huangshi City in Hubei province of China as a fine aggregate replacement for regular sand in concrete. The mix design was carried out for concrete with 35 grade. The sand was replaced with (0, 10, 20, 30, 40, 50 and 60) % iron ore tailings, respectively. The results show that the workability of fresh concrete reduced with the increasing of the iron ore tailings. And the workability can decrease significantly when the iron ore tailings are more than 40 %. Twenty eight days compressive strength and split flexible strength of the hardened concrete specimens exceeded 35 MPa and 5 MPa, respectively, and they reached the maximum when there was 30 % iron ore tailings. Their flex-compression ratio was 1/6 and 10 % higher than that of the control group that used sand as the fine aggregate. The crack resistance of the iron ore tailings concrete was studied at the same time, and the microstructure was observed with an SEM.