Influence On Mechanism And Performance Of Concrete Mixed With Ultra-fine Copper Tailings Sand

The continuous mining of copper mine produces a large amount of solid tailings waste,resulting in the waste of mineral resources and land resources,damaging the ecological environment and threatening human’s health.Rational utilization of copper tailings saves resources and has important economic,ecological and academic values.In this paper,based on the performance analysis of ultra-fine copper tailings,the effects of different dosage of ultra-fine copper tailings on the mechanical properties,durability,microstructure and hydration products of concrete were studied.The effect of pre-wetted tailings on the mechanical and shrinkage properties of high strength concrete was investigated.The main research results were as follows:(1)The mechanical properties of concrete was improved by adding proper amount of ultra-fine copper tailings.The compressive strength of concrete increases obviously after ultra-fine copper tailings composite replaces concrete aggregate and paste.When the replacement rate of ultra-fine copper tailings aggregate is 2%and that of composite paste is 10%,the mechanical properties of concrete are the optimum.(2)The electrical flux of concrete increased with the increase of aggregate substitution rate of ultra-fine copper tailings,and the strength loss of concrete decreased first followed by a increase after sulfate attack.It had little influence on the chloride penetration resistance of concrete,but significantly enhance the performance of resistance to concrete sulfate attack,when the substitution ratio of ultra-copper tailings aggregate was 2%.In the case of different aggregate replacement rates,the effect of ultra-fine copper tailings paste replacement rate on concrete durability was different,but it was positively correlated with the change of compressive strength on the whole.(3)Adding ultra-fine copper tailings into concrete improved the distribution of concrete pores and reduced the porosity of concrete.When the content of ultra-fine copper tailings is 26.7%,the porosity of concrete is the lowest.In this case,the surface of copper tailings is covered with more hydration products and the morphology is smooth and regular,thus increasing the mechanical and durability of concrete.Besides,the hydration products of ultrafine copper tailings-cement-fly ash composite system include CaCO3,C-S-H,Ca(OH)2,SiO2 and Maywnite.With the increase of the content of ultra-fine copper tailings,the characteristic peak of SiO2 increases and the characteristic peak of Ca(OH)2 decreases gradually.(4)The compressive strength of concrete was improved and the self-shrinkage of concrete was reduced by adding pre-wetted ultra-fine copper tailings.When ultra-fine copper tailings were added into concrete as internal curing material,more hydration products were generated to fill the concrete pores,improve the compactness of concrete,and reduce the self-shrinkage of concrete.The mechanical and durability properties of ultra-fine copper tailing mixed into concrete are better than those of ordinary concrete,and it has better economic and environmental benefits.The research proved that ultra-fine copper tailings as concrete admixture with technical feasibility,which provided a theoretical basis for the resource utilization of copper tailings.Figure 31 Table 23 Reference 107...