Ruber Airbag

Description

Rubber airbag, also known as concrete prefabricated hollow slab rubber inflatable mandrel, bridge inflatable mandrel. It is a kind of internal mold with different shapes that can expand and shrink by using the polymer properties of rubber and vulcanizing high-strength fiber cloth. It is mainly used in the pouring and forming engineering of concrete pre-tensioned and post-tensioned beams of highway bridges. It is also used in culvert sewage works. After the rubber airbag is filled with compressed air, the airbag will stretch and expand to meet the cross-section design requirements. The inflation pressure is determined according to the manufacturer's logo, and overpressure inflation is not allowed. It is easy to use, economical and durable, and can be used repeatedly nearly a hundred times. It is soft and shrinks when it is not inflated, and can be folded and curled at will. After it is inflated, it has enough strength to withstand the pressure of concrete. It can replace the original wood formwork, bamboo formwork, and steel formwork, and can be reused many times. It is a supporting product for concrete products that reduces costs and speeds up construction progress.

Feature
1) Scientific and reasonable design
Application of rubber airbags, prefabricated or cast-in-place finished hollow slab girder members can all meet the design requirements, and the rubber airbags are easy to operate, save labor, time and materials.
2) Good performance
The rubber airbag is made of synthetic rubber, natural rubber, and fiber reinforced layer after vulcanization. It has good anti-expansion strength, elasticity, flexibility, and good aging resistance. It can meet the construction and use under various working conditions.
3) Wide range of temperature adaptation
In the range of -10°C to +90°C, the material of the rubber airbag will not change.
4) Lightweight engineering
Rubber airbags provide the necessary conditions for lightweight construction of bridges and construction sites. The weight of prestressed hollow slab concrete components is more than 20% lighter than that of non-prestressed solid components due to the use of rubber airbags. Therefore, reducing the weight of the upper structure of the building can shorten the pile foundation and increase the span, and the on-site construction is simple and safe.
5) Simplify operation
Using rubber airbags, only a few simple tools are used, and the construction process is simple and safe. During construction, you only need to put the rubber airbag into the steel cage. When the inflation pressure reaches the working pressure (according to the pressure gauge and the manual), the concrete is poured. When the concrete is initially set, the rubber airbag is deflated and drawn out to complete Forming of finished components.
6) Environmental protection and pollution-free
Rubber airbags do not pollute the environment. Can be used repeatedly.

Do not over-pressurize when inflated. The working pressure standard of the rubber airbag is as follows.

Diameter(mm)	Pressure(Mpa)
80	0.120
120	0.100
150	0.080
200	0.070
250	0.050
400	0.040
500	0.035
600	0.030
700	0.027
800	0.026
900	0.025
2200	0.005

1. Open the valve first, and close the valve immediately after inflating to the specified pressure.
2. The special-shaped mandrel should be inflated alternately until the specified pressure is reached.

How to use？

Inflatable mandrel construction method:
1. Pneumatic mandrel into the mold
1) Before the inflatable mandrel is put into the mould, it is necessary to inflate the inflatable mandrel on the ground to check whether the inflatable mandrel is damaged or leaked during the previous construction, and to ensure that the inflatable mandrel is intact, so as not to be damaged when pouring concrete. quality hazards in the process.
2) After the concrete pouring at the bottom of the slab girder is completed, the inflatable mandrel is pulled by the rope and penetrated into the steel cage. The inflatable mandrel is relatively large, pulled by It hoist and guided by fixed pulleys. The bundled inflatable mandrel must use white brown rope, and the steel wire rope should not be used to directly contact the inflatable mandrel to avoid damage to the inflatable mandrel.
3) When the inflatable mandrel is inserted, it should be noted that the longitudinal interface of the jacket should be placed upwards to reduce the friction between the jacket and the concrete when pulling.
4)The length of the inflatable mandrel is 60cm longer than that of the plate girder, and the length of each end is 30cm. After the inflatable mandrel is in place and inflated, the joints at the intersection with the end membrane of the plate girder can be ensured to be dense, so as to avoid running out during concrete pouring. The phenomenon of slurry and slurry leakage will cause trouble to the construction.
2. Fixing of the inflatable mandrel
In order to ensure that the protective layer of the slab girder reinforcement and the size of the cavity of the slab girder meet the requirements of the design and specifications, and to prevent the inflatable mandrel from floating during the pouring of concrete, it is fixed with positioning hoop steel bars with a distance of 50cm. The positioning steel bar and the slab girder The steel bars are firmly welded, and the inner diameter of the positioning steel bars is the same as the cavity size.
3. Inflation of the inflatable mandrel
1) After the inflatable mandrel is in place, open the intake valve and inflate with an air compressor. When inflating, use a pressure gauge to control and monitor the air pressure.  When the air pressure reaches the operating pressure, the air valve is closed to stop inflation.
2) Be careful not to exceed the pressure when the inflatable mandrel is inflated.
3) The inflatable mandrel should be inflated before the first use, measure the sufficient time for each set to reach the working pressure, and determine the number of air compressors required according to the initial setting time of the concrete, so as to ensure that the vertical ribs of the slab girder and the upper concrete are in the lower part The pouring begins before the initial setting of the concrete to avoid construction joints and ensure the integrity of the concrete of each slab girder.
According to the field test, the air compressor with 6m3/min is used to inflate, and the inflation time of each set of inflatable mandrel is 15-20min, which takes a short time and has little influence on the formation of concrete construction joints.
4. Concrete Pouring
1) Due to the high-grade concrete used in this project, a retarder is added to the concrete, and the initial setting time reaches 8 hours, so that the concrete at the lower part of the slab girder has sufficient time to complete the supporting of the inflatable mandrel and binding before the initial setting Plate beam negative reinforcement and other processes.
2) When pouring the concrete on both sides of the inflatable mandrel, attention should be paid to vibrating symmetrically from both sides to prevent the left and right displacement of the inflatable mandrel. When vibrating, the inflatable mandrel must not be touched to avoid damage.
5. Remove the inflatable mandrel
1) After the final setting of the concrete, open the valve to deflate, and then the inflatable mandrel can be pulled out from the plate girder.
2) The extraction time of the inflatable mandrel depends on the water-cement ratio, the grade of cement, and the ambient temperature. During construction, it is necessary to observe at any time and pull out the inflatable mandrel in due course. Too early will cause the upper concrete to sag and cause concrete quality defects. If the time is too late, it will not be easy to extract and cause damage to the inflatable mandrel.