The Crack Control Research And Apply Of Over-long And Over-large Area Concrete Slab

With the booming of the over-long and over-large area concrete construction, people focus on how to effectively control concrete cracks in the case of no or less expansion. This article starts from the basis concrete crack control theory of over-long and over-large area concrete construction, explores the mechanism and characteristics of concrete cracks, and puts forward the crack control measures based on the crack control ideas of "resistance and put". And calculating the over-long and over-large area concrete crack control,and use the calculation results in the Chongqing Jiangbei airport T3 terminal block division of the over-long and over-large area concrete construction, applying the theory to practice; At the same time, using the method of finite element software ABAQUS to the alternate bay construction modeling analyses, and exploring the influence of hydration heat and stress between the blocks of different pouring sequence; Finally, crack control analysis is used to the over-long and over-large area concrete construction of Chongqing Jiangbei airport T3 terminal. Through the research and analysis in the whole process, the conclusions just as follows:(1) For the mixture ratio of Chongqing Jiangbei airport T3 terminal’s over-long and over-large area concrete construction, the largest one-time casting length is 44.37 meters calculating by the practical experience formula, and using the length limits to point the bay arrangement, and calculating the typical floor strength, the calculation results meet the requirements.(2) By comparing the result of the calculation of different mixing proportion of C30P8 concrete, it shows that adding the moderate amount of fly ash and slag, reducing the relative dosage of cement, can reduce the production of concrete hydration heat at the same time of improving work performance, but the early tensile strength and tensile limit will be reduced, so it is important to note the amount of the adding.(3) Since the over-long and over-large area concrete pouring, the temperature field has experienced a sharp rise stage, cooling stage after the temperature reached the highest point, and gone down to the environment temperature of stable stage. Among this processes, the first pouring belt and continue pouring belt’s heating value influence each other near the border, but this influence is not enough to affect the maximum temperature rise of concrete block center; continue pouring piece’s maximum stress is increased on the direction of the length due to the boundary constraint, this means that when using the alternate bay construction principle, meeting the requirement of length, the first pieces should be arranged as far as possible and the second block should be relatively reduced, its length should also be relatively reduced.(4) In the over-long and over-large area concrete construction of Chongqing Jiangbei airport T3 terminal, the post-cast strip and expansion strengthening are setted to solve the crack problem in the original construction scheme, through optimizing the original scheme, adopting the alternate bay construction concrete construction scheme of different elevation corresponding water construction, it greatly reduces the construction cost, shorts the time limit for the project, and controls the cracks generation.(5) In the process of concrete construction, the writing of the construction process, the arranging of the alternate bay construction, the using of faster convergent network, the experiment of high performance concrete mix proportion, and the implementation of the construction management system, etc. all of which can be used as experience of the similar construction.