Research On The Preparation Of High Performance Concrete With Iron Ore Tailings Powder

With the development of steel industry in China, the amount of iron ore tailingproduced is increased steadily each year, while its utilization rate is relatively low. ithas been an urgent issue to increase the comprehensive utilization rate of iron oretailing.In this research, iron ore tailing was used as raw material. The property of iron oretailing powder was first used to substitute clinker for preparing cement. The resultsshowed that when0%-20%of cement clinker was replaced by iron ore tailing powderwith similar particle size distribution as inactive admixture, the physical filling effectof iron ore tailing powder did not work properly as expected, and only the strength ofthe blend cement including less that5%of iron ore tailing powder didn’t droped.With the dosage of iron ore tailing powder increased, the strength and fluidity of blendcement were decreased and the stability was qualified, while its setting time and waterrequirement of normal consistency were increased. By mixing iron ore tailing powderwith blast furnance slag powder together, the blend cement with less than10%of ironore tailing powder could reach the equivalent strength of Portland cement without anyadmixture. Moreover the variation of other physical properties of this blend cement hassimilar trend with the blend cement of single-addition iron tailing powder.Iron ore tailing powder was used to replace part of river sand as filling material toprepare concrete, the working performance, mechanical property and durability of thiskind of concrete were investigated. The results showed that the working performance, mechanical property and durability of concrete were affected by replacing river sandwith0%-20%iron tailing powder. With the dosage of iron tailing powder increased,the working performance of fresh concrete declined. In order to keep the constantworking performance of concrete, per1%tailing powder increased required3.7%more of the water reducing agent, the increase of water reducing agent of low-gradeconcrete required was more than that of high-grade concrete. Based the equivalentworking performance of concrete, the compressive strength of concrete increased firstand then decreased along with the increase of the dosage of iron ore tailings powder.The optimum content of iron ore tailing powder decreased gradually with the reductionof water to cement ratio. With the water to cement ratio of0.24and5%of iron oretailing powder, the28d compressive strength of concrete with iron tailing reached102.8MPa, which was risen by26.4%in comparison to the strength of normal concreteat the same age. With the percentage of iron ore tailing powder increased in theconcrete, both the impermeability and frost resistance were improved. Theimpermeability grade of concrete could go up to P12. With the river sand replaced bythe proportion of5%-20%of iron ore tailing powder, the frost resistance of concretewas improved and the level was greater than F400.Scanning electron microscopy and mercury intrusion porosimetry were used tocharacterize the microstructure and pore size distribution of the concrete. With theincorporation of iron ore tailing powder, the aggregate gradation of concrete wasimproved and the concrete was much denser with smaller pore size and reducedporosity.