Effect Of Cement Fineness And Composition On Box Girder Curing Using Cantilever Casting Construction Of PC Continuous Rigid-frame Bridge

Concrete bridge faced with the serious crack question in our country, especially the box body cracking has seriously affected the durability and security of continuous rigid—frame bridge. This article starting with the cement fineness and composition, and the box girder early maintenance measure, in order to provide the new means to solve the box body early time non-structural cracks problem to continuous rigid—frame bridge, and enhance its durability. At the same time, to cement material request and the early maintenance of other concrete bridges also has strong reference function. The paper from the western transportation construction science and technology project ""Research on Effect of Cement Fineness and Component on Bridge Concrete's Performance and Countermeasure (2009318000033)", depends on Qijiang Ganshui bridge, bases of the test data, and takes numerical simulation calculation as fundamental research method, developed the following works:①Collecting the domestic and foreign correlation research materials, to understanding present research situation; analyzing on concrete hydration heat test data, to summarize the rules of hydration heat temperature along with the time variation of cement with different fineness and composition: the efficiency of cement hydration heat generation increases along with the cement fineness increase; adding mineral powder and fly ash to cement,it is useful to reduces the hydrated temperature crack of concrete.②Application finite element computation software ANSYS, numerical simulating calculating to box girder 0 blocks, the general stage hydrated temperature fields with three different kinds fineness cements. The analysis on analog computation results, the efficiency of cement hydration heat generation, the concrete interior thermal peak of box girder, the inside and outside maximum temperature difference of floor and the web plate, as well as the concrete hydration temperature stress value of box girder, all of these increase along with the cement fineness increase. It suggests that the continuous rigid—frame bridge is more suitable to control the cement surface area in the scope of 300m2/kg～350m2/kg.③The concrete hydration temperature effect is remarkable in web plate and the stem stem armpit place of box girder, recommended early maintenance of the continual rigid frame concrete width box, using compound maintenance method: the concrete mould pastes + the automatic spray. It carries on the synthesis early maintenance to box girder. ④Refers to the correlation stipulation of present standard in our country, the domestic and foreign actual projects, as well as the existing research results, it proposed the recommendation target to the cement fineness and composition of continuous rigid—frame bridge. May supply reference for other types of concrete bridge when the cement selection.