1. Install the bottom die. The picture shows the technicians measuring the inverted arch. The function of inverted arch is mainly to reduce the supply of prestress.
Bottom die installation
2. Steel binding. The beam ballast trough plate steel bar and the beam bottom web steel bar are bound separately, and the beam bottom web steel bar and prestressed channel positioning net are bound and formed on the steel bar binding pedestal. The steel binding pedestal is equipped with fixed steel bars and embedded clamping tools to ensure its position is relatively accurate.
Steel binding
3. Suspend the bottom web reinforcement. Hoist it into the beam-making pedestal with two 12.5t gantry cranes. Then adjust the supplementary reinforcement. Install embedded parts. Finally, notify the supervisor to check, and wear rubber pipes after passing the inspection. Please take a closer look at the picture below. There are many white spots on the beam. That's a concrete mat. The function is to ensure that there is a gap between the steel bar and the formwork, that is, to form a protective layer. Block should be placed at least four times per square meter.
Hang the tied steel bar on the bottom die.
4. Wear a tube. Each channel is formed by connecting two sections of rubber pipes. There is a joint in the middle. After concrete pouring, pull out the rubber tube and pull it out from both ends of the beam in the opposite direction.
Wear a rubber tube.
5. Install the template. The template must be cleaned and coated with release agent before installation. Note that the bottom die should be perpendicular to the end die and the side die. Joints should be tight and do not leak slurry.
Clean the template
6. Binding bridge deck reinforcement
Binding bridge deck reinforcement
7. pouring concrete. Before pouring, notify the supervisor to check whether the formwork and reinforcement are qualified. The concrete can only be poured after the supervisor has passed the inspection and signed it. The pouring principle is "bottom plate first, web plate later, top plate last, from both ends to the middle, continuous pouring and molding in layers". The total pouring time of each beam should not exceed 3.5 hours.
Concrete pouring (1)
Concrete pouring (2)
8. Stay healthy. 2 hours after concrete pouring, cover canvas for curing.
Cover maintenance
9. Pull out the rubber hose. When the concrete strength reaches 6-8Mpa, the tube can be pulled out with the permission of the laboratory.
Tube drawing
10. Template removal. When the strength of beam concrete is not less than 25Mpa, the temperature difference between beam concrete core and surface, surface and environment is not more than 65438 05 degrees Celsius, and the concrete water chestnut can be kept intact, the notice of form removal can be issued by the laboratory.
After the formwork is dismantled, the concrete on the formwork must be cleaned immediately for the next use.
form removal
1 1. Because the surface of the formwork is not completely smooth, some pits will be left on the surface after formwork removal. Must be filled with cement slurry.
Fill in some potholes outside the bridge
12. Threaded steel strand. Punching is carried out by winch dragging. After the steel strand penetrates into the hole, both ends extend out for a certain length, which is 750 mm
Threaded steel strand (1)
13. nervous. The prestress of the beam is carried out in two stages, namely, the first stage tensioning and the second stage tensioning. When the strength of concrete is greater than or equal to 33.5Mpa, the first-stage tensioning shall be carried out on the beam-making pedestal. After the first-stage tensioning is completed, the beam shall be hoisted to the beam storage area for the second-stage tensioning. The second-stage tensioning shall be carried out after the concrete age is not less than 14 days and the concrete strength and elastic modulus meet the requirements.
15. Tension (1)
15. Tension (2)
After tensioning, move the beam to the beam storage area.
14. Preparation before grouting. After tensioning, the 75mm long steel strand protruding from the beam is useless and needs to be removed within 24 hours after tensioning. The cutting position is 30 ~ 40 mm away from the work clamp. When grouting, both ends must be sealed, so the gap between steel strand and anchorage must be sealed with cement mortar at both ends of the bridge.
Preparation before grouting
15. grouting. After tensioning, grouting should be carried out within 48 hours to prevent corrosion of steel strand and loss of prestress. Grouting sequence is first down and then up. That is, first press down the tube and then press up the tube. Mudjacking of the same pipeline is carried out continuously and completed at one time. Record grouting time, ambient temperature, slurry temperature, slurry fluidity, vacuum degree, etc.
Mud jacking pump
16. Preparation before sealing. Before sealing, the concrete on the anchorage must be removed. Then the anchorage is rustproof and waterproof.
End cover 1
17. End seal. After grouting, the ends shall be closed within 24 hours. The first picture shows workers installing formwork, and the second picture shows workers pouring concrete. The third picture shows the worker screeding after the formwork is removed.
End cover 2
18. The last process is sealed and coated with waterproof ring.
The last process of sealing layer
19. Waterproof structure. The waterproof effect directly affects the durability of the bridge.
Make a waterproof layer
20. Protective layer construction. 24 hours after waterproof layer construction, protective layer construction can be carried out. The protective layer protects the waterproof layer. In order to prevent the waterproof layer from being damaged and maintain good waterproof characteristics, the concrete used for the protective layer is high-strength glass fiber reinforced concrete.
covering layer
2 1. The workers are coating waterproof materials on the expansion joints of the bridge deck.
Apply waterproof paint
22. After the beam generation is completed. There is a gantry crane in the finished product area. And then transported to the place where the beam needs to be erected.