Usage and Precautions of Rubber Inflated Culvert Balloon

Usage Method

1. Preparation:
   1. Accessories:
      • Accessories (three-way valve, pressure gauge of 0.1 MPa) should be properly connected to the rubber inflated culvert balloon. The release agent is soap powder solution (water: soap powder = 20:1). Evenly apply the release agent on the outer surface of the rubber inflated culvert balloon (at least three applications).
   2. Molding:
      • Use a rope to pull the rubber inflated culvert balloon into the rebar cage with concrete at the bottom, ensuring that the inflation nozzle is placed outside.
   3. Inflation:
      • Open the three-way valve for inflation, and use the pressure gauge to monitor the air pressure during inflation.
      • When the air pressure reaches the operating pressure of the rubber inflated culvert balloon (operating pressure is indicated on the balloon's label), close the inlet valve of the three-way valve.
      • Alternate inflation of the specially shaped rubber inflated culvert balloon until the working pressure is reached.
      • Do not exceed the pressure when inflating.
2. Fixing and pouring concrete:
   1. During the vibration of the concrete, the core mold will float up, so it must be fixed from the top, bottom, left, and right. The spacing of the reinforcement for a rubber inflated culvert balloon with a diameter of 250 mm is 80 cm; if the diameter is increased, the fixing spacing should be correspondingly reduced.
   2. The method of pouring concrete is basically the same as that for solid components. Note to use high-frequency insertion or vibrating rods to vibrate from both sides simultaneously. To prevent the rubber inflated culvert balloon from shifting left or right, it is best not to let the end of the vibrating rod touch the rubber inflated culvert balloon.
3. Removing the mold:
   1. When the concrete begins to set, open the valve to release air. The rubber inflated culvert balloon can then be withdrawn. The time for removing the mold depends on the type of cement used.
   2. After each removal of the rubber inflated culvert balloon. Immediately clean it with a brush (preferably a nylon brush) and tap water to remove surface concrete and keep the surface clean.
   3. Avoid sharp hard objects during on-site use.
   4. After using the rubber inflated culvert balloon, rinse it with clean water. When not in use, store it in a ventilated and dry place, and avoid contact with oils, acids, and alkalis.

Precautions

• When installing the rubber inflated culvert balloon, the length specifications of the hollow core precast beams are usually 8 m, 10 m, 13 m, 16 m, 20 m, 25 m, and 30 m; lengths exceeding 30 m are generally not designed as hollow core beams.
• For culvert balloons below 13 m in length, the inner culvert balloon is generally made of rubber; for culvert balloons above 16 m in length, there is more flexibility in the choice of inner culvert balloons, which can be rubber, wood, or steel.
• During the construction process, the rubber inflated culvert balloon is placed inside the rebar cage, inflated with compressed air to form the desired cavity shape, and withstands the pressure during concrete pouring. After use, it can be deflated and removed from the cavity, allowing for multiple reuse.