Concrete Pouring for the First Foundation Slab of Qingdao New Airport GTC Project
On July 8, the concrete pouring for the first foundation slab of General Traffic Center and Parking Building Project of Qingdao New Airport (GTC) was completed, which was the beginning of the full-scale construction of the project. The concrete for the foundation slab of GTC Project was provided by Qingdao China Railway CNQC New Materials Co., Ltd. The construction of the foundation slab adopted the advanced “batch process” construction technology for super-long concrete structure, which not only can make the duration of the single item decreased by above 20%, but also can make the quality of the project improved significantly.
GTC of Qingdao new airport is the first general traffic center integrating high-speed rail and metro, which can achieve the perfect change nationwide. It is located in the core area of the airport, next to the airport terminal and has the building area of about 0.21 million square meters. Integration of various kinds of traffic modes including high-speed rail, metro and light rail etc. brings higher difficulties to construction of the underground concrete structure with the large span, and the foundation slab of the concrete structure is 373m in length and its monolayer area is more than 60 thousand square meters, which corresponds to 8 standard football fields, so it is the super-long concrete structure in name and in fact.
“For example, for the foundation slab, its length reaches up to 373m and its monolayer area is more than 60 thousand square meters, which corresponds to 10 standard football fields, so it is the super-long concrete structure in name and in fact”, the project manager Wang Yufei said, if carrying out construction using the traditional “post-poured strip method”, the duration of construction will be long and the appearance quality of the as-cast finish concrete cannot be guaranteed, and what is more, many problems such as cracks and leakage etc. can occur easily.
The project department decides to carry out the pouring for the foundation slab using the advanced “batch process” construction technology for super-long concrete structure. “Batch” refers to make the large-area concrete construction area divided into several small areas through using the concrete’s characteristic of releasing internal stress 7 days after pouring and before thorough solidification and then carry out construction as per the principle of “partition programming, construction at a block interval, layered pouring and integrated forming”.
For the GTC project of Qingdao New Airport, the foundation slab is divided into 39 blocks, and the construction is carried out at a block interval like playing Chinese checkers. The pouring for blocks which is not processed before is carried out 7 days after completion of pouring for the first time. The pouring interval of the adjacent blocks is shorter (which is only 1/8 to 1/9 of that of the post-poured strip method), so the construction environments of the concrete are more similar and the pouring quality is more stable. Using the “batch process” construction technology not only shortens the sealing speed of the adjacent blocks, speeds up progress of the project, and what is more, it prevents many problems resulted from post-poured strip area’s long-term exposure in the outdoor environment, such as difficulties in removing the corrosion of the structural reinforcement and removing various dust and chippings pollutants etc. and hence it improves the integrality of the underground slab and the outer wall and reduces leakage of the basement significantly.