Study On Preparation And Adhibition Of The C80Iron Ore Waste Sand Concrete

It will produce large amounts of solid waste when Iron ore is being mining and Ore-dressing. Large accumulation of iron waste not only increases maintenance of mining companies,but threats the surrounding air,soil and water. A huge number of concrete had been producted in China, high quality natural aggregate less and less in many areas. Urgent need to find new sources of aggregate because of the great trouble the high cost and bad aggregate brought to architecture engineering.It’s not only the most effective metheod of absorpting the iron ore waste in quantity that turn the iron ore waste into architecture aggregate,but also can alleviate the pressure of sand resources.It has great ecological benefits and engineering value.At present,iron ore waste sand can be used for the preparation of ordinary concrete maturity,but it can not be used completely for the preparation of high performance concrete strength grade of C80and above owing to that workability and28day compressive strength can not meet the adhibition requirements.The research finded out the difference of iron ore waste sand and gravel in preparing C80high performance concrete through the analysis of raw material properties and different preparation factors,Then prepared C80iron ore waste sand concrete which can be used in practical engineering.The resault shows:(1)The iron ore waste sand meets the basic requirements of building sand after factory processing and can be directly used in concrete production.(2)Choosing the best superplasticizer through the test of cement compatibility;The admixture has mixed a certain proportion of slump retaining agent, retarder and air entraining agent in order to improve concrete workability. The best ratio of reducing agent and the slump retaining agent is8:2.(3)According to the features of raw materials, the optimal water cement ratio is0.25, the optimal amount of cementitious materials is550kg/m3,including349kg/m3cement,55kg/m3fly ash,110kg/m3GBFS and46kg/m3silica fume.(4)The iron ore tailings contain massive powder and have a poor gradation,so that the workability and28day compressive strength can’t meet the design requirements.(5)The C80pumping concrete can be prepared,which workability and28day compressive strength of concrete meet the design requirements,through using washedout sand, increasing the amount of cementitious materials and reducing the maximum size of stone.But there are some problems such as the high cost,water waste and pollution of stone powder discharge after washing.(6)The C80pumping concrete can be prepared,which meet engineering requirements,through adding some natural fine sand into the iron ore tailings, reducing the maximum size of stone and adding some concrete modifier.The best ratio of iron ore tailings and natural fine sand is6:4; The optimal volume of concrete modifier is0.6%of total cementitious materials.