Temperature Effect And Pore-grouting Technology Research In The Pre-process Of Long-span Prestressed Concrete Box Girder

With long-span prestressed concrete beam to increase the size of interface, in addition to the universal application of high performance concrete, cement high temperature enabled the high heat of hydration of concrete, shrinkage, and greater stress, resulting in surface cracking beams and concrete structure Durability will suffer enormous damage to the structure of the use and security problems. So long-span prestressed concrete beams has been caused by temperature stress enough the importance of concrete work has been a major issue, but as a relatively large size of the local pre-stressed concrete box girder, the temperature-induced stress and cracking issues, both at home and abroad and the reasons for its formation mechanism of the study was also relatively small; stages of hydration heat of the temperature and strain changes of the study also lack of adequate data.In this paper, the combination of engineering examples - one bridge 60m large-span prestressed concrete box girder precast entire hole, the use of computer simulation technology, combined with field monitoring data to identify the sea during the construction of mass concrete work intensity, temperature field, stress field with age, such as changes in the law. The success of the project and promote the use of research for large-tonnage long-span prestressed box girder casting process of the overall temperature control of stress and temperature field in the feasibility of developing a new way for future construction of similar projects provided useful information for future depth theoretical study provides experimental and theoretical reference. Bridge project to improve the reliability and durability of great significance.Pore is grouted post-tensioned prestressed concrete structures, one of the most important aspects, the quality of grouting not only because it affects the tendons of prestressed force's anti-corrosion protection, but also affect the structure of the safety of life and durability and does not grouted full structure will change the form of power. Pore compacting grouting is not currently the issue of the construction of the bridge is very prominent. Vacuum grouting is a post-tensioned grouted structural channel new technologies to improve traditional grouting slurry construction is not full and so on, so as to enhance the components of the safety and durability.This article from the box used in the construction process of the principle of vacuum grouting, cement mix requirements, with more than, technical parameters, construction techniques, attention to matters such as vacuum-grouting technology introduced in the construction box, and filling with Experimental study than with the performance of the mud than water, technical parameters and testing methods, drawn from the best test of the cement mix. Construction units for future grouting test at the scene to provide a basis for testing methods, to facilitate the exchange of experience in construction, to improve the quality of the project to eliminate the quality problems, increase the economic benefits are significant.