Shanghai Poly Grand Theater is the first clear water and waterscape theater in China. It consists of 1.5 million grand theater, 400 multi-function halls, rehearsal halls and garages, with a total construction area of 56,000m2, including 36,000m2 above ground, 20,000m2 underground, 6 floors above ground, 1 floor underground and 2 floors locally. This project won the 2065 438+04-2065 438+05 Luban Award of China Construction Engineering.
The fair-faced concrete of this project covers an area of 36,500m2, which is mainly divided into eight types: facade fair-faced fair-faced, stair fair-faced, straight wall fair-faced, curved fair-faced, fair-faced beam, fair-faced board and fair-faced column. How is the construction process implemented for such a large-scale fair-faced concrete project?
Model priority
Experts from all walks of life in China are invited to discuss the local quality deviation in the process of sample guide and on-site implementation.
Decorative model wall
Decorative wall curtain wall embedded parts template
Determination of mixing ratio
Improvement of mix proportion of the first three sections of model wall:
Through the comparative analysis of the pouring process and finished product display of the three-section model wall, the following conclusions are drawn:
A. The water-binder ratio of concrete should be controlled at 0.38 ~ 0.42;
B the sand ratio of concrete should be 0.42 ~ 0.44;
C. In-mold slump shall be170+10mm;
D ductility should be controlled at 400 20 mm.
Expose and solve existing problems. Through the implementation of fair-faced concrete model wall, it is found that there are problems such as panda eye and many bubbles. Through analysis, it is considered that the working performance of concrete can not meet the quality requirements because of the concrete mixture ratio. Therefore, the sand ratio and admixture of concrete were repeatedly adjusted and tried, and finally the best mixture ratio was determined.
Before the construction of the fourth section of the model wall, the mixing station (Shanghai Jiefang Island Urban Construction Materials Company) is required to carry out trial mixing for many times, and at the same time, try mixing the additives, so as to overcome the problem of excessive bubbles on the surface of the samples at this stage and ensure that the fair-faced concrete can achieve the effect closest to the design requirements:
A. there is no obvious color difference on the concrete surface;
B, the bubble area per square meter is not more than 20cm2；;
C. No large number of "tearing" spots, with no more than 10 spots per square meter.
Finally, after the completion of the model wall in the fourth section, according to the opinions of the owner, supervisor, design and other parties, the formal fair-faced concrete construction mixture ratio is finally determined:
Formwork construction
Fair-faced concrete formwork panel adopts high-quality multi-layer film-coated formwork. According to the preliminary test results and site conditions, 100× 100 outdoor enclosure adopts imported WISA formwork (which was later replaced by domestic new port board), and indoor fair-faced concrete wallboard adopts domestic high-quality coated board.
Through comprehensive comparison and analysis, 1 18 formwork support system is specially developed for the fair-faced construction of this project. The system is composed of a peripheral composite frame and the back edge of an internal 40× 100×3 square steel pipe, and the composite frame and the back edge are connected by welding.
Check the template size, flatness, flat-fell seam clearance and screw position item by item.
Template lifting
Template assembly
Five-stage opposite-pulling screw
According to the investigation results of the completed fair-faced concrete project in Japan, the Japanese side adopted a three-joint opposite-pulling screw in the construction, which effectively solved the problem of water loss and slurry leakage at the screw eye and effectively avoided the occurrence of panda eyes. In order to effectively protect the surface of fair-faced formwork, after several rounds of experiments and comparisons, a five-stage counter-pulling screw was specially developed.
The mix proportion of concrete, the flatness of formwork, the tightness of joints and the stiffness of supporting system were tested.
The construction technology of concrete feeding mode and vibrating point position was tested.
"Five-stage template opposite pulling screw" has applied for patent.
postcure
In this project, fair-faced concrete is mainly a vertical component. In order to ensure the curing effect, the curing scheme of concrete covered with plastic film and condensed into water by its own hydration gas is adopted. Immediately after form removal, it is wrapped with plastic film, and the corners are densely planted and compacted. The curing time of concrete shall not be less than 7 days. At the same time, hard protection is adopted on the outer side of plastic film, that is, plywood is covered on the concrete surface to prevent the damage of cross operation to the concrete surface during construction.
In winter construction, it is impossible to spray water for maintenance, so the maintenance scheme adopts the combination of plastic film and flame retardant grass curtain. The curing time of concrete shall not be less than 14 days. Hard protection structure is the same as above.
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