Study On Preparation And Mechanical Properties Of Molybdenum Slag Activated Powder Concrete

Reactive Powder Concrete（RPC）,as a kind of ultra-high performance Concrete,has high strength,good toughness and excellent durability,and has broad application prospects in the field of infrastructure construction in China in the future.However,the high quality raw materials used in the preparation of traditional RPC are expensive,resulting in a small application range.Molybdenum slag is the industrial waste produced by smelting molybdenum metal.The main component is Si O₂,which has a certain potential activity.As the largest molybdenum resource country in the world,China handles 145,000 tons of molybdenum concentrate annually.With the continuous exploitation of molybdenum ore,the accumulation of molybdenum slag is increasing,and the adverse impact on the environment is also increasing.This article is based on the existing theory of reactive powder concrete,the use of molybdenum slag instead of quartz powder preparation of molybdenum slag RPC,make full use of industrial waste as a result of the exploitation of molybdenum,the ease of the waste molybdenum mining after accumulation too much adverse impact on the environment,and to a certain extent,reduce the cost of RPC,has important practical significance.The main research contents of this paper include the following aspects:（1）Molybdenum slag was used instead of quartz powder to prepare Molybdenum slag RPC.Through the design of orthogonal test,the influence of different factors and levels on the mechanical properties of molybdenum slag RPC was explored,and the excellent mix ratio of molybdenum slag RPC with different mechanical properties was given,and the optimal mix ratio of molybdenum slag RPC with different mechanical properties was given.The nonlinear fitting of the test results was carried out,and the formulas of the relationship between different factors and the basic mechanical properties were given.The study shows that the content of molybdenum slag has the greatest influence on compressive strength,and the optimal ratio of RPC compressive strength of molybdenum slag is cement content:content of molybdenum slag:content of steel fiber:water-binder ratio=1.2:0.42:0.15:0.2.The steel fiber content has the greatest influence on flexural strength and splitting tensile strength.The optimal ratio of RPC bending strength and splitting tensile strength of molybdenum slag is cement content:molybdenum slag content:steel fiber content:water-binder ratio=1.2:0.32:0.21:0.2.（2）Through the method of changing the single factor level,the deformation performance test was carried out,and the stress-strain relationship,peak strain,elastic modulus,and Poisson’s ratio under the same factor and different levels were analyzed.The results show that due to the brittleness of RPC of molybdenum slag,the stress-strain curve is almost straight line in the rising stage,and 95%of the peak strain in the elastic stage.The peak strain increased by 23.9%when the water-binder ratio increased from 0.22 to 0.24,and the elastic modulus decreased by 13%when the water-binder ratio increased from 0.22 to 0.24.The Poisson’s ratio of RPC of molybdenum slag is between 0.18 and 0.23.（3）By changing the cement content and molybdenum slag content of molybdenum slag RPC,the age strength test was carried out,and the law of strength change with age of molybdenum slag RPC with different cement content and molybdenum slag content was analyzed,and the age strength formula of molybdenum slag RPC with different ratio was given.The results show that the cement content has the greatest influence on the early stage of molybdenum slag RPC,and the higher the cement content,the higher the early stage strength of molybdenum slag RPC.（4）The micro-analysis test of molybdenum slag RPC was carried out.Through SEM analysis of the distribution of internal holes in concrete,the shape of the generated products,and judge the impact of the generated products on the performance of concrete.The XRD test was carried out to analyze the diffraction peak of the XRD spectrum,and the internal reaction mechanism of concrete was obtained.