Study On Mix Ratio Optimization And Performance Of Manufactured Sand Self-compacting Concrete With High Content Of Stone Powder

Self-Compacting Concrete(SCC)is a high-performance concrete based on excellent flow properties and not affected by external factors during construction.Due to the geographical conditions,economic benefits and the continuous reduction of high-quality natural sand resources,the mechanism sand is considered as a substitute for natural sand,but the high-speed stone powder content of the mechanism sand,sharp and multi-angle of particles,poor gradation and other related problems are restricted.Its application in self-compacting concrete.Therefore,according to the actual situation of the project,the preparation of the mechanism sand self-compacting concrete is of great significance not only for scientific research but also for the promotion and application of self-compacting concrete.Combining the engineering practice with the characteristics of concrete raw materials,the physico-mechanical properties(surface shape,bulk density,sand ratio and particle size)of the aggregate,the volume of the slurry(the amount of water reducing agent,the amount of cementing material)are studied from the perspective of the thickness of the surplus slurry.,fly ash content,water-to-binder ratio)and the effect of stone powder content on the performance of MS-SCC.In order to reduce the non-essential experimental research process for the actual application of the project,and to meet the needs of multiple performance indicators,the following optimization scheme is adopted:using objective weight assignment-grey correlation theory combined with orthogonal test method The optimal mix ratio of the theory is obtained.Finally,the test results of the two mix ratios are compared,and the optimal value of the mix ratio is obtained through the verification test.Under the conditions of this test,the optimum mix ratio of C50mechanism sand self-compacting concrete includes 550kg/m~3 of cementitious material,0.28 of water-binder ratio,25%of fly ash,52%of sanding rate and dosage of water reducing agent.0.8%,meeting the mechanical properties and durability of the later stage while meeting the requirements of SCC performance.In order to eliminate the influence of man-made or environment,an evaluation index based on the thickness of the surplus slurry is proposed to describe the performance of the self-compacting concrete.The angular and angular coefficients of the coarse and fine aggregates obtained by image processing technology are 1.19 and1.055,respectively.The water-to-binder ratio and sand ratio are kept constant,and the relationship between the thickness of the surplus slurry and the work performance and mechanical properties is established.It was found that changing the thickness of the surplus slurry can significantly affect the working performance and mechanical properties of the concrete.In order to ensure the fluidity,stability,segregation resistance and homogeneity of the fresh concrete mixture,the thickness of the surplus slurry should be controlled as far as possible to the interval of 62.21?m<tp<80.79?m.In this interval,the concrete is pressed for 28 days.The strength is still higher than the design strength,but for better working performance,tp=80.79?m is taken as the suitable surplus slurry thickness,and the cementing material at this time is 550 kg/m~3.