The Research On The Preparation Of Ultra High Strength Self-compacting Shrinkage Compensating Concrete Filled Steel Tube With Manufactured Sand

Ultra high strength concrete filled steel tube refers to the combination of concrete filled steel pipe filled with more than C100 compensation shrinkage concrete.Ultra high strength concrete filled steel tube has the advantages of high bearing capacity,strong anti deformation ability and good durability,it has a broad application prospect in the large span concrete filled steel tube arch bridge in the western mountain area and the anti seismic combined high pier engineering.In view of the shortage of natural river sand resources in the western mountainous area,using the manufactured sand to prepare ultra high strength concrete with poor working performance,large shrinkage,and placing of ultra high strength concrete in pipe is not easy to compact.This paper based on the science and technology project of Sichuan province transport department of ultra high strength self compacting concrete filled steel tube research and application?2015TZ0057?and the construction of Sichuan Guang'an Guan Sheng Qu Jiang concrete filled steel tube arch bridge,Special research has been carried out on the preparation of ultra high strength self compacting shrinkage compensating concrete filled steel tube by using manufactured sand.The main research results in this paper are as follows:1.The hydration activity of different mineral admixture?silica fume,fly ash,fly ash microbead and mineral powder?and the influence of the plastic viscosity and yield stress on the cement paste are studied systematically.The effect of compatibility between mother solution and functional component of admixture on the performance of ultra high strength concrete filled steel tube is discussed.The special admixture of ultra high strength concrete filled steel tube with low gas content,hyper dispersity,viscosity reduction and high slump loss resistant is developed.The design method of improving the working performance of concrete by synergistic optimization of mineral viscosity reduction and admixture components is put forward.2.The influence of different mixture ratio parameters,such as the composition and amount of cementing material,the ratio of water to binder,the rate of sand,the type of manufactured sand,fineness modulus,the content of stone powder and the maximum size of aggregate,on the working performance and mechanical properties of concrete were systematically studied.The effect of stone powder on the performance of concrete in the manufactured sand can be reduced by optimization design and development of The special admixture of ultra high strength concrete filled steel tube.Therefore,on the basis of the"construction technical specification of the highway bridge and culvert"JTG TF50-2011,the limit of the stone powder content in the manufactured sand of the ultra high strength concrete filled steel tube can be loosened properly.For C100 concrete-filled steel tube,the content of stone powder must be less than 10%,and the content of stone powder for C110concrete-filled steel tube must be less than 5%.The optimal mixture ratio of ultra high strength concrete with manufactured sand is cement:fly ash microbead:silica fume:manufactured sand:gravel:water:=503:114:83:690:1035:126.The initial slump/extensibility of the C110 ultra high strength concrete is 270/630mm,and the extensibility loss of 2h is less than 20mm,T₅₀₀ is 10s,the gas content is 1.9%,28d compressive strength is 134.4MPa.3.The influence of different expansive agents and steel fiber on the mechanical properties and volume stability of ultra high strength concrete filled steel tube is investigated.A compound expansive agent for ultra high strength concrete filled steel tube with HCSA,MgO and gypsum is developed.The volume stability of ultra high strength concrete-filled steel tube is significantly improved by the combination of steel fiber and composite expansive agent.The mechanical properties of ultra-high strength concrete filled steel tube with manufactured sand,The preparation technology of ultra high strength concrete-filled steel tube with manufactured sand is put forward.,and the C100^C140 self compacting shrinkage compensating shrinkage ultra high strength concrete filled steel tube was prepared by the manufactured sand.4.The research results have been applied to the Guang'an Guan Sheng Qu Jiang concrete filled steel tube arch bridge.The test results show that the C100 self compacting shrinkage compensating ultra high strength concrete filled steel tube is filled densely.The construction and quality control technology,including the selection and quality control of raw materials concrete,mixing and pumping jacking technology,and the testing method of concrete density,has been formed.