Research On Effect Of Fineness And Components Of Cement On Durability And Potential Security Of Pc Continous Rigid Frame Bridge

PC continuous rigid-frame bridge is widely used in the highway and city bridge which has such advantages as beam continuous without expansion joints and comfort driving as continuous bridge, no bearing as T-frame bridge. In recent years, excessive mid-span deflection and cracks in box girder appear in the long-span continuous rigid frame bridge in used, which affect load bearing and serviceability and greatly reduced durability of continuous rigid frame bridge.According to the recommendations and brief outline of Western Transportation Technology Projects,"Research on Effect of The Fineness and Components of Cement on Concrete's Performance in Bridge and the Countermeasures",this paper discussed the effect of the fineness and components of cement on durability and potential security of PC continuous rigid-frame bridge.The author tried to provide a new way to solve the disease of PC continuous rigid-frame bridge from the material point of view.To improve the durability and potential security of the bridge,the paper advicied new fineness and components of cement and expect the fineness and components of cement have a strong reference to other style of bridge.The results of this paper show that, the high surface area, high C3S content of the cement which used in PC continuous rigid-frame bridge the present will have a adverse influence on achievement of long-term strength growth, on the hydration heat of concrete, shrinkage and creep,and will lead to early deterioration of concrete easily. A single 28-day compressive strength of concrete can not comprehensive measure the performance of concrete, does not reflect long-term strength growth of concrete and resistance to cracking. PC continuous rigid frame bridge should use the middle-hot cement which have smaller surface area, the lower C3S content and higher C2S content.It will provide a help to realise the long-term strength growth, maintain and improve the carrying capacity of bridges, avoid of the formation and development of box girder cracking, control of excessive span deflection.The author advised the concrete's conservation of PC continuous rigid frame bridge should beginning from pay attention to choice of raw materials to the process of concrete practice and the conservation.Concrete should use the cement of middle- hydration hot and reasonable water cement ratio.the paper recommended experimental method for how to evaluate the cement and mix of concrete and the new way of concrete's conservation and appropriate time to remove the mouldboard.The author advised to carry out a more rigour standard about cement used in PC continuous rigid frame bridge on the basis of the national standard.At last of the paper,the author provide a new fineness and components of cement which he think it is appropriate.