Great Living Engineered

TUNNEL FORM CONSTRUCTION TECHNIQUE AT ROHAN ABHILASHA, PUNE

28th April 2017

WHAT IS TUNNEL FORM CONSTRUCTION?

Tunnel form is a formwork system that allows the contractor to cast walls and slabs in one operation on a daily cycle. It combines the speed, quality and accuracy with the flexibility and economy of in-situ construction. Construction durations are reduced significantly by this rapid system when compared to conventional methods. Tunnel Form System brings speed, quality and accuracy to concrete construction and provides big savings in finishing and M&E works. Hi-tech technologies for steel formwork production make tunnel forms strong & durable. The system creates efficient load-bearing structures which are known as the most earthquake resistant structures.

The result is a cellular reinforced structure, the surfaces of which are sufficiently high quality to require only minimal finishing for direct decoration, while the end walls and facades are easily completed with thermally insulated units that can be clad as required. The system creates an efficient load-bearing structure for use in a wide variety of applications. It is particularly effective in projects suited to repetitive cellular construction such as residential blocks, hotels, student accommodation, barracks and prisons.

WHY TUNNEL FORMWORK SYSTEM?

 

It is economic…

- With one set of formwork, 500 times laying works can be fulfilled in the same project. 

- Low cost adaptation to the other similar projects can be provided by adding new formworks and by repairing the older formworks. 

- Since it is managed by a limited number of highly qualified foremen, their assistants and regular workers, it ensures significant cost saving in labor costs. 

- The cost of financing the construction capital is considerably decreased since it speeds up the construction period compared to the classical systems. 

It is fast and reliable…

- It is a formwork system that allows the contractor to lay wall and slab concrete at a time on a daily basis. Therefore, one layer can be constructed with a set of formwork everyday.

- It can be laid up in the spans required by the project. It can easily be worked in the spans varying from 1.5 meters to 6.5 meters.

- It is the most reliable system, which is well known to be resistant against earthquakes. Likewise, it is the most reliable system against severe winds and storms. 

It is safe…

 - It has integral working platforms and edge protection systems, ensuring considerably successful results in terms of work safety. 

 - In addition, the repetitive, predictable nature of the tasks involved encourages familiarity with operations, and, once training is complete, productivity improves as construction progresses.

 - The minimal requirement for tools and equipment when moving the tunnel form further reduces the risk of accidents on site.

 - It is fire resistant.

 

It provides High Quality…

 

 - It ensures the correct application and the completion of the Project in start-up quality. 

 - It is possible to build up to 40 storey buildings by laying the wall concrete a little thinner on upper storey. 

 - Since the measurement errors are almost non-existant during the production, it provides convenience in the applications of precast facade wall and panel interior wall. 

 - Since very smooth concrete surfaces are obtained from the formwork surfaces, wallpaper covering and painting works are carried out by minimum costs such that there is no need for plastering after concrete. 

 

It is environmentally friendly… 

  - It is known to be environmentally friendly as no wooden material is used. 

  - Heating and air conditioning costs are considerably less compared to the conventional buildings. 

  

HOW DOES IT WORK – THE 24-HR CYCLE?

The basic construction sequence is shown in the diagram. In summary, the forms are positioned, steel reinforcement is fixed and concrete poured and left overnight to cured. The next day when the concrete has hardened tto around 60%, the tunnelforms are then lowered, removed, the area then backpropped and the tunnelforms are then positioned for the next days work. This way a team of 20-30 workers can complete 500m2 +/- of slab and wall construction daily.

Rohan Abhilasha

 

COMPARISON OF CONVENTIONAL / ALUFORM / TUNNEL FORM

 

 


Activity


For Conventional


For Aluform Shuttering


For Tunnel Formwork


Capital Cost


Less


Cost of shuttering material is high


Cost of shuttering material and other related machinery is very high


Casting System


RCC Frame structure of beam, slab, column etc. casted separately


Monolithic structure of walls and ceiling casted together


Monolithic structure of main walls and ceiling casted together. Internal portion walls build after words.


Accuracy and Quality of construction


Less


Good accuracy but with proper care


Good accuracy


Internal/external Plastering required


Required


Not required if good precaution taken.


Not required if good precaution taken.


Design Changes


Flexibility in design to incorporate any changes before casting


Used for Repetitive design/mass construction. Changes in design is difficult to incorporate.


Used for Repetitive design/ mass construction. Changes in design is difficult to incorporate.


Speed of work


Slow


Moderate to Fast


Fast


Cycle time for RCC work


20 days


10 -15 days


1 days repeat cycle possible with proper infrastructure and other ancillary machineries


No. of repetition of shutt material


12 to 15


100 to 150


500 +


Advantages


Low cost easy to operate,


High cost but more effective to operate low manpower, moderate to fast construction, with modification can be used to other project, most suitable for high rise and mass housing.


Long lifespan, low manpower, speedy construction, high reusability, with modification can be used in other project with little different, most suitable for high rise and mass housing.


Limitations


Short lifespan, Slow speed poor quality


Moderate lifespan & manpower required, moderately high speed of construction, moderately high investment


High investment, Work only with tower crane.


Need well experienced skilled people. Need many other ancillary machineries to achieve 1 day repeat cycle


Cost of shuttering


Around Rs 400 to 500 /sft of shuttering floor area


Around Rs 5000 to 6000 /sft of area


(1000 X 5 to 6 times)


Around Rs 9000 to 10000 /sft


(2500 X 3.5 to 4 times)


Extra almost equal cost for ancillary machineries.


Labour Cost


Around Rs. 85 to 100 /sft slab area


Around Rs. 175 to 250 /Sft slab area


Around Rs. 250 to 300 /sft. slab area.

 

MACHINERY REQUIREMENT (TO ACHIEVE 24-48HR SLAB CYCLE)

 

 

    • Tower Crane of 10 ton capacity

 

    • Welded Wire mesh machine

 

    • Concrete Distributor

 

    • Gas heaters (for cold climate)

 

    • Batching Plant

 

    • Hydra

 

    • Other routine machineries

PANEL ASSEMBLY

LIMITATIONS OF TUNNEL FORM

 

    • Not suitable for small projects, and if there are many variations in design

 

    • High initial investment of formwork and other machineries.

 

    • Imported formwork, need 5 to 6 months early finalization of plan.

 

    • Dependent of formwork supplier for amendments in form work and accessories.

 

    • Wall thickness need to keep 200 mm thick as no offset for column beams possible.

 

    • Need to design building suitable for system.

 

    • Due to speedy construction, high cash flow management required.

 

    • Basement storey cannot be constructed by using tunnel formwork system, removal of formwork is not possible.

 

    • Various geometrical forms and angles are difficult for which special formwork to be designed, which will be very expensive

 

    • Due to high production speed management-related functions are vital. Coordination problems may cause remarkable delays in schedule.

 

    • Skilled labor force is needed compared to traditional systems.

 

 CASE STUDY – ROHAN ABHILASHA, PUNE

 

    • Location – Wagholi, Pune

 

    • Plot Area – 30 acres

 

    • No of blocks – 7

 

    • No of Buildings – 25

 

    • LG+G+13

 

    • Total apartments around 2200 nos

 

    • Slab area with tunnel form around 23 lac sft and parking around 7 lac sft

 

    • RCC duration 2 years

 

    • With 2 sets of tunnel form (5000 sqft)

 

ACTUAL CONSTRUCTION

Rohan Abhilasha

Rohan Abhilasha

DAY 1 – 1st slab (14th Oct)

Rohan Abhilasha

DAY 10 – 3rd slab or 6th casting (25th Oct)

Rohan Abhilasha

DAY 20 – 6th slab or 12th casting (6th Nov)

Rohan Abhilasha  

DAY 40 – 10th slab or 20th casting (24th Nov)

 

FINISHING ITEMS

Due to the use of tunnel form construction technique, which is a rapid construction technique, the finishing items too needed to be completed at the same speed in order to avoid any bottlenecks. The following technologies have also been used at Rohan Abhilasha to complement the speed ot tunnel form.

 

1. PRECAST STAIRCASE

 

 

2. TILTING TABLES FOR PRECAST UNITS

 

3. TOILET PODS

 

 

CONCRETE MIX DESIGN

 


Design Parameters


Details


Grade of concrete


M 40


Strength requirement


12-15 Mpa in 12 Hours


De-shuttering period


12 hours according to strength


W/C ratio


Minimum 0.27


Slump


180mm after 90 minutes


Accelerators


Non – chloride accelerators to be used


Cement


53 grade Max 400 kg/cum


Fly ash


Minimum 10 – 15 % (replacement for cement )


Admixture


PCE base admixture

 

Strength Comparison (with admixture)

 


Particulars (per cum.)


Design for Non-Heating


Design for Heating


Cement


380 Kg


330 Kg


Flyash


60 Kg


90 Kg


% replacement


13.63 %


21.42 %


WC Ratio


0.28


0.3


Admixture dose


1%


0.81%


Heating Time


-------


4.5 Hours


Heating Cost


-------


75 to 100 per cum


12 Hours strength


13.5 Mpa


14 Mpa


7 days strength


45 Mpa


34 Mpa


28 days strength


58 Mpa


48 Mpa

 

 

 

THANK YOU

 

 

YouTube Videos:

Timelapse video of Tunnel Form technology at Rohan Abhilasha: https://www.youtube.com/watch?v=0eE5KHJzHdo

Rohan Abhilasha Project Execution:

https://www.youtube.com/watch?v=yaykCTluGa8

How Tunnel Forwork works (in Animation):

https://www.youtube.com/watch?v=z_CCKgA_o9k

 

Abhishek Bhatewara

Rohan Builders

A: 1201, Divya Shakti, 100ft road, Indiranagar, Bengaluru 560 038

 W: www.rohanbuilders.com | E: abhishek@rohanbuilders.com