Research On The Durability Of Graphite Tailings Concrete

As China is in the stage of large-scale infrastructure construction,the consumption of raw materials and gravel has gradually increased.In addition,since graphite as a strategic resource,many of the tailings produced by graphite mining for many years have harmed the environment.At present,hydraulic concrete research mainly focuses on work performance and mechanical properties,and neglects the important influence of durability factors during service.Therefore,it is of great significance to study the durability of concrete in hydraulic engineering.In order to make maximum use of graphite tailings and solve the durability problem of hydraulic concrete,this paper systematically studied the permeability and shrinkage performance of graphite tailings concrete and the resistance to chloride ion erosion under dry and wet cycle conditions,including the following work:(1)Through the macroscopic and microscopic analysis of the graphite tailings,it is proved that the physical and chemical properties of the graphite tailings are consistent with the conditions of the admixture,and the three different water-cement ratio concretes are replaced by the volume method instead of the sand.Taking the substitution ratio of(0~40%)graphite tailings as the research variable,the shrinkage test of 15 prismatic specimens was carried out by non-contact method,and the variation of the specimens with time(0~180d)was measured.Analysis of contraction mechanism.The test results show that the shrinkage tendency of graphite tailings concrete tends to be stable after 100 days,the optimal replacement rate of graphite tailings is 10%,and the concrete is the most compact.(2)Taking(0~40%)graphite tailings substitution rate as the research variable,the experimental study of 60 round-plate anti-seepage specimens was carried out by water pressure method and water seepage height method.The test results show that a small amount(10-20%)of graphite tailings can improve the impermeability of concrete.The optimal substitution rate of 10% can improve the impermeability of concrete.The test result of seepage height is the ratio of water seepage height and relative permeability coefficient.Relevance provides a basis for compliance with actual engineering applications.(3)With the graphite tailings substitution rate,water-cement ratio and erosion age as the main variables,75 cubic specimens were tested.The basic theory of chloride ion transport in saturated and unsaturated concrete is briefly described.The test results show that the longer the graphite tailings have the effect of inhibiting chloride ion erosion,the smaller(10~20%)graphite tailings can improve the corrosion resistance of concrete shallow layer,and the large substitution rate helps.Improves deep resistance to chloride ion attack.It is recommended that the water-cement ratio of hydraulic concrete(dry and wet circulation areas)should not be too large,generally not exceeding 0.44.