Study On The Preparation Of RPC From Quartz Sand Tailings And Its Performance

Yinan county is rich in quartz sandstone mineral resources.It is an important raw material supply base of quartz sand in shandong province and even in China.After more than 20 years of development,it has become an industrial cluster integrating mining,quartz sand processing,product sales and related supporting industries.Greatly promoted the local social and economic development.The annual production scale of quartz sand reaches more than 6million tons.Due to the grain size screening range of 0.125mm-0.71mm(25-120 mesh)for quartz sand enterprises,most of the quartz sand tailings below 0.125mm(120 mesh)are not fully recycled,and more than 1 million tons of quartz sand tailings are produced every year.However,if waste from tailings is not handled properly,it will fly with the wind when dry and flow into rivers when raining.As a result,the river will be blocked and the environment will be damaged,which not only causes waste of resources,but also causes pollution to local air.At the same time as the construction of concrete performance requirements continuously improve,scholars in the 1990 s,puts forward the concept of high performance powder concrete(RPC),high performance of the powder concrete is put forward the main design of the durability of the concrete indicator,promote the progress of the concrete industry research and development of high performance concrete powder leap,broke through the original concrete technical limitations,to save energy and protect the ecological environment,the engineering application and so on various aspects has good effect,so the development of high performance concrete will become the mainstream of the concrete in the 21 st century.Therefore,this paper mainly studies the rational use of quartz sand tailings waste to eliminate its pollution and harm.High performance active powder concrete was prepared.Based on the compounding principle of RPC,active powder concrete(RPC)was prepared by using local quartz sand tailings as micro aggregate.In combination with the practical situation of weapons in the local raw materials,on the basis of past RPC configuration,using local quartz sand tailings instead of quartz powder in the raw materials as aggregate,using quartz sand as fine aggregate content is 1.2,10% amount of fly ash to replace cement,silica fume content 0.2,steel fiber content is 2%,0.85% dosage of water reducing agent,water/cement ratio 0.23,heat curing condition got better liquidity,compressive strength 173.9MPa,32.6 MPa bending of ultra high strength concrete,provide theoretical reference to realize local tailings recycling.In this paper,standard curing and thermal curing were adopted.According to the most compact packing theory,the influence of the incorporation amount of raw materials such as fly ash,silica ash,water reducing agent and steel fiber on theperformance of RPC was studied,and the microstructure of RPC was analyzed by XRD and SEM.The test results show that :(1)in the process of RPC preparation,250 tailing can be used instead of quartz powder as micro aggregate and steam curing method can be used to prepare by optimizing particle gradation.(2)based on the initial mixing ratio of RPC,control the variation of the mixing amount of each raw material,and obtain the optimal mixing ratio of RPC;(3)RPC prepared by the optimal mixture ratio was selected.Under the condition of steam curing,the volume shrinkage rate at 120 days was 320x10-6,and the electric flux at 6hours was less than 10 C,and the carbonation depth at 56 days was less than 1mm.It had better volume stability and durability.(4)the XRD and SEM test results of RPC net slurry showed that the incorporation of fly ash and steam curing was conducive to the improvement of the process of the internal hydration reaction of RPC and the densification of RPC structure.