What is the pouring sequence and method of cast-in-place box girder?

The following is the pouring sequence and method of cast-in-place box girder brought by Zhong Da Consulting for your reference.

The concrete is poured in two times, the bottom plate and web plate are poured first (pay attention to the rebar embedded in the chamfer of the top plate), and then the top plate is poured. Concrete pouring sequence of beam body: the same concrete is poured from the middle of the span to both sides, and finally the length of each side of pier top is 3 m. When pouring concrete for the first time, web concrete should be poured first, but it should be poured symmetrically and evenly to prevent the internal model from being biased due to uneven stress. When the concrete is poured to half the height of the web, the concrete of the bottom plate should be poured again. When vibrating the joint between the bottom plate and the web plate, attention should be paid to prevent the web plate concrete from collapsing excessively. After the bottom plate is poured, the web concrete should be poured again (the pouring time of the web concrete should be controlled so that there are no construction joints, and the concrete cannot collapse to the bottom plate due to premature vibration), and the web concrete should be higher than the root of the flange plate 1cm, so as to prevent the concrete slurry from leaking out of the web when pouring the top plate, which will affect the appearance quality. After the completion of pouring, chisel the hair after the final setting, and clean the poured concrete surface with a water gun.

When vibrating the web, attention should be paid to avoid contact with corrugated pipes, anchor pads and places with dense steel bars. Insert a vibrator or a plunger with a diameter of 3cm to ensure the density of concrete there. The vent hole should be fixed firmly (the vent hole is made of soft plastic pipe), and the lining reinforcement should be fixed on the web reinforcement. When vibrating the soleplate, use a flat vibrator.

Before the construction of the next tensioning section, the tensioning end of the previous tensioning section should be roughened and cleaned, and finally the concrete of the next tensioning section should be poured to prevent cracks.

During construction, manholes should be set at the top of the box, with the position of l/6L(L is the span), the dimensions of which are 1.2m along the bridge direction and 1.0m across the bridge direction, with chamfers of 20cm×20cm at the four corners and chamfered steel bars. The four sides of the manhole are made into inverted splays, which should be blocked in time after cleaning.

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