SLIP FORM WORK

AR. SAURABH YADAV

PROF. ARCHANA SINGH RATHORE

TO BE COVERED TODAY

• Introduction to formwork

• Types

• Importance

• Slip formwork

• Horizontal construction

• Vertical construction

• Material use

• Safety

FORM WORK

• Temporary boarding or sheeting erected to contain freshly placed and compacted concrete until it has gained sufficient strength to be self-supporting.

IMPOTANCE OF FORMWORK

• Formwork system is the key factor determining the success of a construction project in terms of

• SPEED

• QUALITY

• COST

• SAFETY OF WORKS

Classification according to materials of construction

• WOOD

• most popular formwork material-low initial cost-high adaptability to complicated shape-labour intensive and environmental unfriendly

• •

• Steel- • hot-rolled or cold-formed sections-heavy weight-suitable

for large-sized panels

• •

• Aluminium- • stiff and light weight-higher material and labour cost-

excellent finish

WHAT IT IS?

Slip forming, continuous poured, continuously formed, or slip form construction is a construction method in which concrete is poured into a continuously moving form.

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• Method of vertically extruding a reinforced concrete section and is suitable for construction of core wallsi n high-rise structures – lift shafts, stair shafts,towers.

• The formwork rises continuously, at a rate of about300 mm per hour, supporting itself on the core and not relying on support or access from other parts of the building or permanent works

In vertical slip forming the concrete form may be surrounded by a platform on which workers stand, placing steel reinforcing rods into the concrete and ensuring a smooth pour

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In horizontal slip forming for pavement and traffic separation walls concrete is laid down, vibrated, worked, and settled in place while the form itself slowly moves ahead

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Placing Concrete Underwater

Advantages: Can be used to funnel

concrete down through the water into

the structure.

Watch for: Discharge end always

has to be buried in fresh concrete to

ensure seal between water and

concrete mass.

ONCE UPON A TIME……

• The slip forming technique was in use by the early 20th century for building silos and grain elevators.

• In the 1947-1950 period, AT&T Long Lines built 49 concrete towers up to 191 ft tall for microwave relay stations; most using the slip-form method.

• The technique was introduced to residential and commercial buildings in the late 1960s.

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The first notable use of the method in a residential/retail business was the Skylon

Tower in Niagara Falls, Ontario, which was completed in 1965

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Components of vertical slip form:

HOW DO WE DO IT ?

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il

Slip form structural detail

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HOW DO WE DO IT ?

ADVANTAGES

The main advantages can be listed as:

(i) quicker construction;

(ii) less formwork;

(iii) less scaffolding;

(iv) easier working conditions;

(v) greater salvage;

(vi) better concrete;

(vii) a joint less, watertight structure.

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Slip form wall

made of 1:12 cement and quarry-dust/ sand mix with 2% of coir fibers. The steel shutter is used For slip form wall construction. Some types of soil can also be used instead of quarry dust.

Cost-effective Walls

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Slip form wall

construction

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BASIC SEQUENCE

• The formwork and the access platform are assembled on the ground.

• The assembly is raised using hydraulic jacks.

• As the formwork rises continuously, continuous concrete and rebar supply are needed until the operation is finished.

• At the end of the operation the formwork is removed using a crane.

• The entire process is thoroughly inspected and highly controlled

BENEFITS • Careful planning of construction process can achieve high

production rates

• Slip form does not require the crane to move upwards, minimising crane use.

• Since the formwork operates independently, formation of the core in advance of the rest of the structure takes it off the critical path – enhancing main structure stability.

• Availability of the different working platforms in the formwork system allows the exposed concrete at the bottom of the rising formwork to be finished, making it an integral part of the construction process.

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BENEFITS

• Certain formwork systems permit construction of tapered cores and towers.

• Slip form systems require a small but highly skilled workforce on site

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• Other considerations • This formwork is more economical for buildings more than

seven storey high.

• Little flexibility for change once continuous concreting has begun therefore extensive planning and special detailing are needed.

• Setting rate of the concrete had to be constantly monitored to ensure that it is matched with the speed at which the forms are raised.

• The structure being slipformed should have significant dimensions in both major axes to ensure stability of the system.

• Standby plant and equipment should be available though cold jointing may occasionally be necessary

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THANKS!!!