Construction Steps of a Highway Underpass in UAE
This is the commentary of a video which shows the construction steps of an underpass. To watch the video, please click the below link
An underpass is a tunnel containing a road or pedestrian passageway running underneath a road or railway
Formation works
- Coordinates and levels are marked by the surveyor where underpass is to be constructed.
- According to that the soil is excavated for foundation works.
- Soil is excavated 30cm from blinding top level given by the surveyor.
- After excavation, water is sprayed and compaction is done for more strength.
- The strong soil called road base is spread above that in layers.
- Each layers is spread and compacted well.
- Strings are connected between the levels given by surveyor.
- Road base is made 10cm below from this level.
- Now our formation is ready for blinding.
Plate load test
- Plate Load test is conducted and ultimate bearing capacity of soil is calculated.
- After the passing of test, Foundation works starts.
Blinding
- Blinding is the Base for Base slab.
- Form work of blinding is done.
- Points are checked and levels are marked by the surveyor.
- Polythene sheets are placed on the ground for preventing leakage of concrete slurry.
Concreting
- We are doing concrete using Concrete pumps.
- The concrete pump is set in Suitable position.
- Now concrete for pouring comes in an RMC vehicle.
- Concrete Sample is taken from the vehicle for Compaction test and Slump tests.
- If the slump result is positive, then we start pouring concrete to input box of pump.
- Water the place before concrete.
- Now Pump pour concrete to the required location.
- The pouring is controlled by the operator with a remote according to the requirement.
- Tamping and Spreading is done by using Punchas and small shovels.
- Finishing is done using Bull floats and trowels.
- After setting, Hessian cloths and polythene sheets are used for curing.
Waterproofing
- A primer called polyprime SB is applied for waterproofing
- After drying of primer, a water proofing membrane called Bitustick is applied on it.
- Suitable overlaps are given for good waterproofing.
- Water proofing here is done to prevent the entry of water from below to the structure
Screed
- Then screed concrete is provided above this waterproof membrane for its protection.
- Screed thickness is 5cm
- Shuttering and concreting is done similar to the blinding.
- After its curing, we starts Base Slab works.
Base slab
Steel works
- The Steel work is done above the screed according to the drawing.
- Cranes are used for the shifting of steel Bundles.
- Bottom steels, Chairs, Face bars, Top steels are placed and tied firmly using the binding wires.
- Starter bars for the upcoming walls are also provided for the connection.
- Cleaning is done before form work fixing.
Form works
- Meanwhile the Form works can be fabricated.
- Form work is fabricated using soldiers, GTX or H20 beams, and Plywood.
- It is cleaned and rebool oil is applied in it for easy removal.
- Coordinates of base slab is given by the surveyor on the ground.
- After steel inspection, form works are placed on that points.
- Strong supports are given to the ground.
- The is water stop fixed between construction joints of base slab and wall for prevention of water entering.
- Coordinates are checked and the form work is adjusted to the required point.
- The Levels of concrete are marked.
- Kicker shutter is also made for the support of upcoming walls in the dimension of wall.
- Formworks and its supports are inspected thoroughly.
- Covers of steel are checked.
- Level pipes are fixed for leveling.
- Now its ready for concrete.
Concrete
- Materials for concrete such as Generators, water, converters, vibrator needles, leveling machines etc. are arranged.
- Pump is set. Water is sprayed.
- During the Concrete pour, Mechanical vibrators are applied thoroughly.
- Concrete is placed layer by layer up to top.
- When it reaches top, leveling machine is operated and the concrete is leveled.
- Level pipes are removed.
- Then finishing is done using Bull floats.
- So base slab concrete is done.
- Curing is done. Hessian cloth and polythene sheet is used for efficient curing.
ΓΌ
Up to now we have seen the construction of
blinding, waterproofing above that, screed and base slab. Now we are going to
do the RCC walls
RCC walls
- In the construction joints between base slab and walls, scabbling is done
Scaffolding
- For the steelworks access scaffolding is to be made.
- Access scaffolding is made using cup-lock scaffolding materials.
- Now its ready for steel works
- Steels are fixed according to the drawings.
- Crane is used for easiness of works.
- Main bars, face bars etc. are fixed and tied using binding wires.
- Cover blocks are fixed for suitable covers.
Form works
- Wall Form work is fabricated using soldiers, GTX or H20 beams and plywoods.
- Form works are made according to drawing size.
- They are cleaned and rebool oil is applied.
- Form works are lifted using crane and fixed in correct position in touch with kicker below.
- Support is given using soldier props, push pull props etc. it is connected to concrete blocks or drilled to base slab.
- Connections are made between different Form works. Formtape is applied in joints.
- Tie rods are connects between shutters on both sides.
- Form works are aligned according to surveyor coordinates by adjusting the supports.
- Verticality is checked using the plumb bob.
- Level is also marked.
- The Form works and supports are to be thoroughly inspected and is made strong so that it can withstand the upcoming concrete.
Concrete
- Concrete setups are arranged.
- The concrete pump is set. Concrete came in the RMC vehicle.
- Concrete is placed layer by layer upto top
- Effective compaction is done at each layer.
- Curing is done at the top using hessian cloth and polythene sheets.
Deshuttering
- Deshuttering done after Hardening of concrete.
- Wet Hessian cloths with Polythene sheets are used for curing.
- Scaffolding are also removed.
- Like this the other RCC walls is also constructed.
Remaining Steps will be updated in the next video.
Thank You.
