Preparation Of High Performance Concrete With Iron Tailings And Barron Rocks As Aggregates

Consider that the production and accumulation of tailings is large,combinedwith the shortage of natural sand and gravel aggregate situation,To large-scale andhigh value-added use of tailings,we study the basic nature of the typical iron tailingsand waste rock aggregate,as well as the mechanical properties and durability of C80high performance concrete which is made by iron tailings and waste rock,and conducta scale sleepers pilot test by tailings and waste rock aggregate.1) systematic study the phase composition of grain size distribution and itsrelationshipiron,physical and mechanical properties,gradation characteristics,particlemorphology and surface characteristics of iron tailings and waste rock aggregate. Theresults showed that: the chemical and physical composition is same of the samesource tailings and waste rock aggregate,the relationship between particle size islittle,there is no enriched SiO2； the chemical composition of different sources of irontailings and waste rock aggregate is different.The basic physical and mechanicalcharacteristics of Miyun tailings and waste rock aggregate selected in line with therequirements of concrete sleepers.Miyun tailings have the potential alkalireactivity,but by incorporating25%of fly ash can restrain tailings potential alkalireactivity.2) The Three-axis sizes, roundness and sphericity of two coarse aggregates madefrom limestone and waste iron tailings rocks were determined by Image-Pro Plus (IPP)software in this paper. The statistical distributions of the isometric ratio, roundnessand sphericity of the different sized coarse aggregates composed of200particles werestudied by Statistical Product and Service Solutions (SPSS) software, and therelationships among the three parameters were established. The results indicate thatthe isometric ratio, roundness and sphericity of the different-sized limestone and irontailing aggregates used in this study all obey the normal distribution approximately,and the three parameters have good consistency in characterizing the particle shape ofvarious or different sized coarse aggregates. Furthermore, the relation among thesphericity and isometric ratio and roundness of the coarse aggregates fits in a highlysignificant binary linear regression model.3) Study the mechanical properties and durability of whole tailings and gravel aggregate C80concrete,and compared with concrete by limestone、diabase、sand andmanufactured-sand.Tailings Aggregate concrete can be used to prepare C80concrete,but slightly worse than conventional aggregate concrete in mechanicalproperties.By microhardness analysis:the range of interfacial transition zone wholetailings concrete is larger than natural gravel aggregate concrete,and the minimummicroscopic hardness of interfacial transition zone is small in whole tailings concretethan natural gravel aggregate concrete,the incorporation of silica fume cansignificantly improve the interfacial transition zone.4) Study the steam curing system of whole tailings C80sleepers concrete,todetermine the best time to stop static,constant temperature and holdingtime,comparative analysis the mechanical properties of the steam curing and standardcuring,the results show that the the28-day compressive strength of the steam curing islower than standard curing.5)Studied the durability and stability of the whole tailings C80sleepersconcrete.The performance of sleepers concrete made in laboratory is that:antifreezelevel> F300,electric flux <200C,sulphate resistance level> KS150,carbonation depthof0.In terms of stability,shrinkage,creep and creep coefficient of whole tailingsconcrete is less than the natural gravel aggregate concrete. Shrinkage,creep and creepcoefficient of steam curing is less than the standard curing concrete.6) Finally,conduct a scale Ⅲa sleepers pilot test by tailings and waste rockaggregate,the compressive strength of trial production of sleepers is more than80MPa,and static load cracking strength to meet the standard requirements.