Large Span Prestressed Concrete Continuous Rigid Conservation Methods Of Early Research Pouring Concrete Cantilever Segmental Box Girder Structure

In recent years, due to the superiority of large span prestressed concrete continuousrigid frame box girder, it has been widely used in bridge construction, highwayconstruction, especially in mountainous areas. However, because of the larger size ofbox girder, lot of heat generated by concrete pouring cement hydration, coupled withconcrete after release, it is difficulties that the maintenance of working surface ofconcrete box girder bottom slabs, as well as the construction site environment factors,making the concrete box girder produce large cracks. Meanwhile, the performancerequirements for the concrete work, the composition of modern concrete has undergonegreat changes, in order to achieve our desired objectives, we must take the necessaryconcrete curing methods to suppress the generation of the early cracks in the concrete,thereby increasing the life of the bridge.This paper combines science and technology project of Chongqing Jiaotong"long-span prestressed continuous rigid frame bridge cantilever construction of theresearch process section section of the conservation process," from the impact of theconcrete composition and curing conditions on the early performance of concrete, andsummed up a set of early conservation methods suitable for large-span prestressedconcrete box girder cantilever pouring concrete segments from the necessity of concreteearly conservation, that mold paste+automatic spray conservation.It resolves thelong-span diameter prestressed concrete box girder cantilever segmental pouringdifficulties and problems early cracks early curing concrete. The main contents includethe following：①In the thesis,describes the research background; outlines the early shrinkage ofconcrete research status and cracking; overview of the cantilever box girder segmentpouring concrete curing methods and problems early, study. the existing problem.②In comparing the difference between concrete and modern concrete in the past,based on the study of the cantilever box girder construction and structural characteristicsand performance requirements for concrete cement admixture, water reducer,conservation methods on the early performance of concrete and presents theperformance characteristics and the need for early conservation of early modernconcrete.③Summed up a set for large span prestressed concrete box girder segment pouring concrete cantilever method that die early curing paste+automatic spray maintenance,and support projects combining the effects of conservation methods were tested.