Research On The Key Construction Technology And Preparation Of HPC Shishou Yangtze River Highway Bridge

In this paper,we focus on the technical problems of high performance concrete mix design and construction quality control of the main bridge structure of Shishou Yangtze River Highway Bridge.The research is based on high performance concrete raw material selection,mix design;crack control,durability and construction quality control.Application of fly ash+mineral powder+etarded high performance polycarboxylate water reducer"Three-doping"technology,we were studied the effects of mineral admixture and polypropylene fiber on the comprehensive performance of concrete emphatically.The use of different conditions for large volume structure of the simulation calculation to optimize the best working conditions,and to develop the relevant temperature control technology standards,measures.According to the relevant technical measures and on-site temperature control monitoring,we could effectively control the occurrence of harmful cracks,and ultimately to achieve the concrete in the bridge project of high performance.First of all,based on the combination of crack resistance and durability of the design concept and used of hydration heat,adiabatic temperature rise,mechanical tests and supplemented by carbonation,chloride ion permeability test,we ultimately optimize the ultra-retardation,low hydration heat temperature rise,high durability of the C40 concrete for the main pier large capacity platform.For the different requirements of pumping performance and cracking resistance,we were designed the C50 concrete in different sections.The results show that the content of C40 is417kg/m~3,the content of fly ash is 35%,the content of powder is 17%,the ratio of water to cement is 0.35.In addition,for the construction of the platform,the incorporation of 0.75kg/m~3 polypropylene fiber for the concrete and the top 50cm construction of concrete,improve the tensile strength of concrete itself,to ensure that the bearing platform and the top surface could shrinkage cracks and have a good appearance quality.The dosage of C50 concrete is 471~497kg/m~3,the content of fly ash is 10%~17.5%,the ore powder is 0~11%,the sand rate is 40%~42%,the water glue ratio is 0.31.The solid foundation of the lower column of the lower column and the anchoring zone of the upper column are added to the appropriate proportion of polypropylene fiber,and the crack resistance is better.Secondly,the temperature field and stress field are calculated and analyzed by different working conditions in the solid foundation of the main pier and the lower part of the lower tower.The maximum crack safety factor(>1.4)is determined.In addition,the corresponding temperature control standard and detailed,effective and feasible temperature control measures of concrete during the construction period and maintenance period are formulated.Combined with the corresponding measures,the temperature monitoring of the concrete is monitored in real time.The temperature monitoring results basically meet the requirements of temperature control Mold looks better,no visible cracks.Finally,according to the requirements of wide box girder structure,strong reinforcement and crack resistance and durability performance,combined with the practical experience of concrete engineering of wide box girder with the same type of bridge,the effects of mineral admixture ratio on concrete are studied.The results show that the total amount of concrete aggregate is 496kg/m~3,15%of fly ash and15%of slag and supplemented with appropriate retarding polycarboxylate high performance water reducing agent,which has good working performance and mechanical properties,early crack resistance,long-term volumetric stability and durability.In addition,the paper puts forward the measures such as pouring order,fabric method,vibrating method and maintenance measures of wide box girder concrete,and forms the construction technology and quality control technology of C55 high performance concrete with wide box girder.