The Research Of Influence Of Concrete Material And Maintenance Factors On Early Crack Of Cantilever Casting Concrete Bridge

Recently,a period of time,many of the concrete bridges in our country have appeared a large number of cracks,which has become the focus of the construction workers and the researchers concerned.Cast-in-situ concrete construction method is widely used in concrete bridges in our country,so to ensure the work of on-site pouring concrete,concrete including slump,expansion of the loss,pump and other indicators,so the composition of modern concrete changed,but the concrete composition change of concrete early performance produced great influence,increases the possibility of cracks.At the same time,the early performance of concrete is not only related to the composition of the concrete,but also with the climate environment,construction maintenance measures and so on.Therefore,we must clear relationship between concrete composition which composition and construction of the early environment temperature and concrete early performance and seek reasonable optimization of concrete composition,properties and compatible with concrete curing measures and environment,so as to ensure the cast-in-situ concrete to build the quality,prevention and control of concrete cracks.For the cantilever pouring concrete box girder,and its construction of special.Analysis of concrete composition and maintenance of the early construction of the impact of cracks,help to optimize the concrete mix ratio and improve the maintenance environment,prevention and control of cracks.Through extensive collection of relevant experimental data and Bridge regular inspection report and analysis of influence of concrete composition and curing of the concrete mixture early hydration heat and temperature contraction;evaluation the Ganshui bridge concrete raw material selection,with ratio optimization and composite curing method application effect;relying on the Longju Bridge,through the finite element analysis under different conditions of temperature and humidity,hanging general segmental concrete box girders at the beginning of the stress state,combining the process of cantilever construction and demonstration Longju bridge construction using composite curing method is reasonable.Specific completion of the following work:(1)To collect and analyze a large number of existing tests and literature materials,analyze the influence of modern concrete composition and maintenance factors on early performance of concrete.(2)To collect and utilize the test report of the cast-in-place bridge of modern concrete cantilever,summarize the crack situation of the bridge.The finite element method is used to analyze the initial stress in the construction period of the typical crack bridge,and the possible reason of the crack is put forward.(3)Elaborated the Ganshui bridge in Qijiang box girder concrete raw material selection,concrete with than the use of optimization test and construction composite curing method,the actual crack detection according to demonstrate optimum selection of raw materials and composite curing methods fertilization of suspending cast box beam in duration and anti cracking techniques rationality,for future application to provide the reference.(4)Relying on the expressway Longju Wanli Bridge engineering analysis,different age,different environment temperature and hydration heat temperature difference or seasonal environmental factors and whether to use a wet cover and bottom die mold paste case,early cantilever general segmental concrete box girder should stress state,the argument Longju bridge using the rationality of the composite curing method.