| With the development of mineral resources,the discharge of solid waste such as copper tailings and steel slag is increasing,resulting in the accumulation of a large amount of tailings,which not only occupies land,pollutes the environment,and even endangers the safety of people's lives and property.Although copper tailings have achieved certain results in the research of valuable metal recycling and building materials,they still have problems such as small scale of utilization and low comprehensive utilization rate.At the same time,investment in infrastructure construction such as roads is increasing,materials such as natural sand are consumed enormously,and excessive exploitation destroys the ecology.The use of copper tailings,steel slag and other wastes with resource characteristics for road construction will not only save resources,reduce tailings inventory,but also reduce the massive consumption of non-renewable resources such as gravel aggregates,and prevent ecological destruction.Based on the above research background,this paper takes copper tailings produced in Huangshi,Hubei as the research object,and conducts basic performance tests such as chemical analysis of copper tailings and steel slag raw materials,water swell rate test,and the feasibility of applying the materials in road engineering analysis,The mixing ratio design of the cement-stabilized copper tailings material is preferred to optimize the mixing ratio of the mixture.Further,the macro-mechanical properties of the material are combined with the micro-test to analyze the solidification mechanism of cement-steel slag stabilized copper tailings material.Finally,a triaxial creep test is conducted on the stable material to investigate the creep properties of the material under different confining pressures.In order to promote the application of copper tailings and steel slag in road engineering,and find a practical way for the resource utilization of copper tailings and other solid wastes.The research results are as follows:(1)The chemical composition,environmental impact,physical and mechanical properties of coppers tailings are analyzed,and the chemical composition and stability of steel slag are analyzed to demonstrate the feasibility of materials used in road engineering materials.(2)Based on the tests of unconfined compressive strength,splitting and compressive modulus of resilience of stabilized materials,the mix proportion of cement stabilized copper tailings is optimized.Finally,it is determined that the optimal ratio of stable materials is 6%cement,the ratio of steel slag to copper tailings is 1:3,Under the condition of 96%compaction,the optimal ratio is 7d unconfined compressive strength is 3.19MPa and 90d indirect tensile strength is 0.69MPa,which meet the requirements of light traffic at the base level of the second and below roads and the strength of the base level of the roads at all levels.(3)The binary image processing of the scanning electron microscopy pictures found that with the increase of curing age and the increase of the amount of steel slag,the porosity of stable materials gradually decreased.The porosity of the optimal ratio at 28 d curing age is 6.929%,which is 11.518% lower than that at 7d(7.831%);Compared with the same cement content(6%)and age(28d),without steel slag group(porosity 10.149%),the porosity decreases by 31.727%.The corresponding macro-mechanical characteristics are that the strength of the material has increased,and the stress-strain curve shows a clear yield platform.(4)A triaxial creep test is conducted on the stable material,the creep characteristics of the material under different confining pressure conditions are analyzed,and based on the test results and material characteristics,a nonlinear creep model suitable for describing the stable material is established.The parameter inversion of the nonlinear creep model based on the particle swarm optimization algorithm shows that the model can better describe the creep law of stable materials. |
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