Tailings Aggregate Green High Performance Concrete With Mix Design And Application Research

This thesis mainly studied mix proportion design method of preparation Green High Performance Concrete by use the tailings aggregate and its application. According to the principle of the maximum aggregate packing density, Proposed a design method of calculate mix ratio of tailings aggregate high-performance concrete by the fixed gravel volume parameters and combined with the absolute volume method. Experimental study on the relationship between the performance of concrete (workability, strength, durability) and the parameters(the parameters of gravel volume and water-cement ratio, etc.) in the design. According to the special performance requirements of concrete, the mixture ratio design method proposed in this paper are verified, the results are effective.Through the study of performance of tailings aggregate concrete obtain the following conclusions:When preparing the concrete strength requirements of60～80MPa,1m3concrete the bulk volume of coarse aggregate of0.75m3～0.80m3, fine aggregate content is(with mortar volume count)43%～47%, adjustment through admixture the concrete workability can be made from vibration molding to pumping construction; when the concrete strength requirements up to80MPa and the slump is required, besides aggregate should have dense accumulation and reduce the water cement ratio, grain size distribution of cementitious materials, chemical activity matching and thermal curing are effective ways, to excessive increase admixture made the concrete bleeding, and are detrimental to the performance of the concrete.Green high performance concrete of tailings aggregate water cement ratio of0.40～0.30, corresponding to the28d compressive strength of concrete is55MPa～80MPa; under the conditions of the same water-cement ratio,28d compressive strength of concrete increases with slurry volume decreased(Which the total volume of the coarse and fine aggregate increasing), but reduced to a certain value(admixture excess added) and then decreased, the results show that the surface slurry thickness of aggregate or slurry viscosity of cement has a optimal value. Through the study of the relationship between water-cement ratio and28d strength, Combining with JGJ55-2011"The mix proportion design specifications of ordinary concrete" and obtain the regression coefficients of suitable for preparation tailings concrete. αa、 ab were respectively0.811and0.799.According to the design method of mixture ratio proposed by this paper, the concrete with330kg/m3cement and the mixture’s slump up to220mm,and7d and28d compressive strength of36MPa and62MPa respectively was prepared by the fine sand in full tail sand and waste rock aggregates completely replacing natural sand and gravel aggregates、slag powder and fly ash and retarding polycarboxylate superplasticizer, and the performance indicators meeted the design requirements.Compared with the subway segment concrete which use the same raw materials in factory at present, subway segment concrete is formulated according to the design method of mixture ratio proposed by this paper, which has smaller amount of paste volume, higher mechanical properties, better durability, cost-effective higher performance etc.