Construction steps of a Highway Underpass-Part 2

In this Video, we ill see the Underpass works such as;

Top Slab
1. Scaffoldings and Platforms
RJR scaffoldings used.
Parts of scaffoldings joined using cranes or hiabs.
fixed on the base jacks on the firm surface, to the required height.
Toe boards are fixed above for the working platform.
Top U head is adjusted
Steel I beams are placed above the U heads
Now H20 timber beams are placed above. The clamps are used for connection between . Spacing's and laps are maintained
Plywoods are fixed above the H20 beams.
In the joints of plywoods, filler is used to avoid the leakage of concrete slurry. Masking tape is used for its proper application.
Scabling of Walls are done for proper bonding.
Then the plywood surface is cleaned well using air blower.

2. Steel works
Steels are shifted above using crane according to the bar bending schedule.
Suitable cover blocks are used
Bottom steels, chairs, face bars, top steels are tied. Steel coming from the wall are interconnected properly.
Steels for the upcoming approach slabs and Parapets are tied in advance before concreting.
Proper space, lap between steels, binding is to be maintained and is to be thoroughly checked by the Engineer.
Small conduit Pipes for electricity is to be provided before concreting.

3. Formworks
Formworks are fixed on all sides using cranes.
Tie rods are used
Formworks near upcoming approach slab side, and formworks near upcoming parapet sides are fixed according to its shape.
Surveyor will check the coordinates and levels.
Verticality, alignment, connections etc. are checked.
Pipes are fixed above for correct level and for movement of levelling machine.
Concrete setups are arranged.

4. Concrete
Concreting is done in layer by layer.
Mechanical vibrators are applied in each layer.
Continuous placing of concrete is needed to avoid the cold joints between the layers.
levelling machine, shovels, punchas, Bull floats are used
Proper curing is done using hessian cloth and polythene sheets.

Parapet
Parapet concrete is done here in two stages.
Bottom portion is done first.
In 2nd part, formwork is with a design. So special formwork is prepared and cleaned properly.
After remaining steel works, form work are fixed. And concreting is done.


Approach slabs below underpass
Ground is prepared using Excavator.
Road base soil is placed for good strength.
After curing, primer for water proofing is done.
Waterproofing membrane and board is applied.
Steel works and formworks are done.
Concreting is done with proper compaction. Then finishing. Thereafter curing.

Concrete above base slab
After removal of all top slab scaffolding, the base slab area is cleaned.
Formwork and concreting is done above the base slab with suitable slope and levels of road.
Wearing course is coming above this.

Waterproofing outside the RCC walls
Outside wall is finished well using the grinders.
The waterproofing primer is applied
Waterproofing membrane is applied above that after the required time.
Then protection board is applied above that and a firm pressure shall be applied.
In this waterproofed portion we can fill the soil layer by layer up to required height. On each layer Density tests are conducted.
Soil filling works are done in parallel to MSE wall works since the soil is to be laid on portion between walls and MSE walls.

MSE wall works
Setting out of the MSE walls.
Formworks and concreting of levelling pad is done.
There are different types and shapes of soil panels which are designed according the load, location etc.
They are fixed and levelled using spirit levels and using surveyor coordinates.
Supports are given.
Geotextile Cloth provided
Soil is filled layer by layer up to the attachments and then friction ties of suitable load is tied with soil panel and is fixed to the ground using steel.
When soil reaches top, panels are placed above. And the process continues up to top.
Top of soil panel, precast capping beam is fixed.

Approach slab above
Above approach slabs are constructed same like below approach slabs.

Protective coating
Its procedures include finishing of rough surfaces using grinders, water jetting, primer application, 1st coating, Filler application and Final coat application.

Road Works
Road base is laid and asphalting is done. Interlocks are laid on sides.
Suitable lighting arrangements are provided. Guard rails are fixed.
After suitable markings and placing of traffic signs, the underpass and way is opened for the traffic.

Well planned and properly executed infrastructural works, will considerably reduce traffic congestions and improves standards.
Hope you will review the works. Thanks for watching.