Study On Pore Structure Fractal And Reliability Of Tailings Ball Concrete Under Chloride Erosion

In most of the researches on tailing concrete,gravel or tailing ore was used as coarse aggregate,and tailing powder was used partly or completely to replace sand or cement.In this paper,iron tailings pellets were used to replace the coarse aggregate of ordinary concrete,and iron tailings powder was used to replace fine aggregate.The homogeneity of concrete components and microscopic pore structure were closely related to the properties of materials.At present,studies on the difference between non-uniform aggregate settlement and microscopic properties of tailing concrete under chloride erosion were relatively scarce.Ordinary concrete C,tailing ball concrete T and steel fiber reinforced concrete TF8 were soaked in 3%mass fraction sodium chloride solution for 15d and dried for 15d.Compressive strength,split tensile strength test,gas permeability test and chloride ion permeability test were carried out through repeated dry and wet cycles for 30,60,90,120,150 and 180 days.Consider aggregate settlement for the distribution of the pore structure of concrete,and the influence of aggregate settlement of microscopic pore structure parameters of erosion level and age related,hardened concrete microstructure test system Rapidair457 respectively test the bottom,A and B to the top of the erosion and erosion air content,bubble spacing coefficient,average chord length,microscopic pore structure parameters such as specific surface area,bubble frequency.Considering that the influence level of aggregate settlement on the fractal dimension was related to the age of erosion,the fractal dimension of hole axis of base surface A and top surface B was calculated by combining the spacing method and line segment box dimension method.The Monte Carlo method was used to calculate the reliable indexes of base A,top B and nonaggregate differential face axis,and to calculate the correlation between the reliable indexes and mechanical properties and impermeability parameters.Finally,the internal relations of micro,micro,fractal of hole axis and reliability of tailing ball concrete were analyzed.The results showed that the compressive strength,splitting tensile strength and gas permeability resistance of concrete cube increased and then decreased with the time of erosion due to the compaction of salt crystal,and the iron element in tailing concrete promoted the diffusion of chloride ion.The coarse aggregate tailing pellets have stronger fluidity than gravel,which leads to the concrete aggregate settling more obviously.Steel fiber has an inhibitory effect on tailings ball sinking.Due to the subsidence of aggregate,there were differences in the distribution of pores in the erosion surfaces of A and B.With the growth of erosion age,the transition zone of coarse aggregate interface becomes clear gradually,that was,the differences gradually disappear.The distribution of micro pore structure was closely related to gas permeability coefficient,fractal dimension of hole axis and reliable index.The macro and micro properties,fractal shape of hole axis and reliability of ordinary concrete and tailing ball concrete show similar variation rules with the increase of erosion age.