Production And Experimental Research On Mechanical Properties Of Iron Tailings-pumice Concrete

With the increasing demand of concrete in modern society,the storage capacity of sand and stone is declining.Suitable environmental protection aggregates are urgently need to cope with the resource crisis.Concerning with the practical condition of Zhangjiakou,natural pumice and iron ore tailings can be the aggregates to make the new environment-friendly lightweight aggregate concrete.In this paper,the research on aggregate characteristics of natural pumice and iron ore tailings is made,and determination and optimization of reference concrete mix proportion are given.The influence of pumice particle sizes,sand ratio and fly ash on the property of pumice concrete are also studied.This paper achieves the iron ore tailings replacement ratio,water reducing agent and silica fume via orthogonal experiment.Finally,the strength of the lightweight aggregate concrete can reach 45 Mpa.Pumice in Zhangjiakou is reddish brown,with rich outer holes and irregular shape.The bulk density is 692 kg/m~3,and the cylinder compressive strength is 2 MPa.The void ratio is greater than 50%,while the bibulous rate is below 20%,In order to improve the strength of the pumice and reduce the water absorption rate,sealing treatment should be done on the pumice,after which the cylinder compressive strength reaches 4.3 MPa,and the water absorption rate drops to 11.1%.The density of iron tailings density is 1460 kg/m~3 and fineness modulus is 2.3,which is similar to the ordinary sand.On the basis of reference concrete mix,the test changed alone pumice particle sizes,sand rate,fly ash and iron ore tailings replacement rate.The results showed that using 2.5~20 mm continuous particles of pumice sealing can get the maximum strength.When the sand ratio were taken 30%,33%,36%,39%,the amount of fly ash was 10%,20%,30%,40%,the strength increased with the increasing of sand ratio,but the workability gradually became poor.When the fly ash content is 20%,the strength reached the peak value.The iron ore tailings replacement rate has great effect on workability of lightweight aggregate concrete.Finally,this paper took the orthogonal test and variance analysis method to test the influence of the strength of lightweight aggregate concrete.The effect of water cement ratio was the most significant,water reducing agent was next,followed by the silica fume,and iron ore tailings replacement rate of the weakest effect was not significant.