Research On Mixing And Performance Of Medium And Low Strength Concrete With Large Content Of Tailings Micro Powder

“Energy saving,emission reduction,and low-carbon development” everywhere embodies the importance of the country’s environmental governance in the new form,and the healthy development of green high-performance concrete is imperative.Cement,mineral admixtures,machine-made sand,etc.will emit some dust and harmful gases and other pollutants during the production process.Many related companies have gradually been taken away,and natural resources have also been reduced.In this case,we must research and develop new products to replace natural mineral admixtures to deal with the current situation.The new development concept of “technological innovation,turning waste into treasure”points to us a new technical route.Some piles of “waste”,such as stone powder in the production of machine-made sand,fine tailings in tailings,etc.,are all It is a new product that we should research and develop.At this time,a large number of metal tailings in the metallurgical industry have caused adverse effects on the ecological environment.At present,the utilization rate of iron tailings is low.The use of iron tailings in the field of building materials is an important way for the efficient recycling and utilization of iron tailings.Help promote the development of the concrete industry in a green and sustainable direction.Designed in accordance with the existing JGJ55-2011 “General Concrete Mixture Design Regulations” standard requirements(hereinafter referred to as the “Code Method”),the formulated medium and low strength(C15-C30)large fluid concrete mostly contains large water-to-binder ratios and cementitious materials Too little,it is easy to have poor working performance such as poor slurry encapsulation,bleeding,and compaction.In order to solve the above-mentioned problems,in the process of designing the mix ratio of medium-low-strength and large-fluid concrete,this project adopts the preparation technical route of low water-binder ratio,low cement content and large content of iron tailings fine powder,and uses “Design method of ready-mixed concrete mix ratio based on raw material quality”(hereinafter referred to as the “new method”)has been verified by a large number of experiments: the main research is that the two kinds of iron tailings fine powders have a large amount of iron ore tailings(30% to 70%).The workability,strength,volume stability,durability and microstructure of fluid concrete have been verified through a series of experimental studies to verify the feasibility and correctness of this preparation technology route.The application of large flow concrete provides technical reference.Through a large number of experimental verifications,it can be known that:(1)When the amount of fine iron tailings powder used in concrete reaches more than 40%,the amount of cementitious material should not be less than 370kg/m3;For medium and low strength fluid concrete,the content of fine iron tailings should not be more than 60%,and the water-binder ratio should not be less than 0.38;(2)Workability:When the content of iron tailings fine powder is 30%～70%,the workability of medium and low strength fluid concrete is significantly improved and improved;(3)In terms of strength:When the maximum content of fine iron tailings is 40%,it can meet the design requirements of C25 mix ratio;When the maximum content of fine iron tailings is 50%,it can meet the design requirements of C20 mix ratio;When the maximum content of fine iron tailings is 60%,it can meet the design requirements of C15 mix ratio;When the water-binder ratio is less than 0.43,the amount of cementitious material is370kg/m3,and the maximum mixing amount of fine iron tailings is 30%,which can meet the design requirements of C30 mix ratio;(4)In terms of durability:A large amount of iron tailings fine powder is used in C25 and C30 concrete,and the test data of its anti-chloride ion penetration performance shows: “The design method of readymixed concrete mix based on the quality of raw materials” is compared with JGJ55-2011“Common concrete mix design specification” Compared with the method,the former is better than the latter;A large amount of fine iron tailings powder is used in C25 and C30 concrete,and the frost resistance test data shows:The frost resistance of C25-A-1(up to F200)and C25-B-1(up to F200)mixed with a content of 30% is higher than that of the benchmark C25-J(up to F150);30% of C30-A-1-T1(up to F200),C30-B-1-T1(up to F200)and the benchmark C30-J(up to F2000)concrete have the same frost resistance;(5)Through the use of low water-binder ratio,low cement content,and large amount of iron ore tailings micro powder in the medium and low strength fluid concrete,a large amount of experimental data verifies that “the design method of ready-mixed concrete mix based on the quality of raw materials” is feasible.