What Is Slip Formwork in Constructions?
What Is Slip Formwork in Constructions?
Slip Formwork is a construction technique in which concrete is poured into a continuously moving form to create structures such as bridges, towers, buildings, dams and roadways.
This method allows for the creation of seamless continuous concrete structures with superior performance characteristics compared to those made using discrete form elements.
Slip forming relies on the ability of concrete to set quickly and requires a balance between workability and quick-setting capacity.
The freshly set concrete must be strong enough to support the form and the weight of the new concrete as well as withstand the vibration of compaction machinery, in order to create a stable structure.
Slip formwork construction is a method that is used to build tall, specialized structures quickly and efficiently. Examples of structures that can be built using the slip formwork method include cooling towers, chimneys, silos, roadways and bridges.
This technique involves continuous monitoring of the concrete pouring and setting process to ensure that the forms are being raised at a consistent rate.
Slip formwork construction is typically only used for structures taller than 16 meters and relies on automation to build structures at a rate of up to 7.2 meters per day making it one of the fastest and most cost-effective techniques in the construction industry.
Types Of Slip Formwork
The following are the types of Slip Formwork;
Vertical Slip Formwork
In the vertical slip formwork method, hydraulic jacks are used to lift a form and platform for pouring concrete in an upward motion.
This method relies on the concrete setting quickly and gaining initial strength while still being pliable, and is based on the principle of extrusion which is frequently used in concrete construction.
Horizontal Slip Formwork
Slip formwork paving is a method of laying concrete for pavement or traffic separation walls where the form used to shape the concrete as it sets is slowly moved forward as the concrete is being poured, vibrated and worked to ensure proper settling. The form remains horizontal during the process.
Cantilever Jump Form Method
The slip formwork method involves the use of a formwork structure that is attached to a climbing device and does not require cranes.
This formwork can be used to construct walls, columns, supports and floor beams at the height of a single story. The climbing formwork system provides maximum safety and does not require cranes for operation.
Egg Shaped Slip Form System
The jump form system is able to accommodate any geometric shape because it is based on the jump form principle. This system allows for individual curvature adjustments by altering the axis and vertical circumferential slope on each side of the wall. These adjustments can be made to achieve optimal working conditions.
Canonical Slip Formwork
Canonical slip forming is a method of building structures with constantly changing dimensions and wall thicknesses in a monolithic way without any steps or breaks. To achieve this, formwork structures that can be moved horizontally are mounted on hydraulically adjustable tapering elements.
The overhead girder star is the central point of the tower and connects all the main beams to create a uniform, closed scaffold. It also serves as an upper work platform.
Components Of Slip Formwork
Vertical forms are used in the construction process to shape concrete and can be made of various materials including metal, wood, plywood, or glass-fiber reinforced plastic.
Wales are used to support and hold vertical forms in place, as well as scaffolding and other platforms.
Yokes are used to lift and support the weight of the structure and to transmit lifting forces from jacks to the wales.
Jacks are mounted on jack rods and provide the necessary lifting force to the slip form system.
Jack rods are climbed by jacks.
Advantages Of Slip Formwork
- The Slip form construction is the economical method for the construction of high-rise structures.
- It requires less labor for its construction which ultimately saves the labor costs.
- Better finished surface achieved and does not require plastering.
- The Slip Formwork does not require a crane to move it in the upward direction.
- Slip formwork helps to achieve high production rates.
- It provides more safety to the workers and proper working space so that the labor can work efficiently.
Disadvantages Of Slip Formwork
- Very high initial cost.
- Time consuming process for arranging various components
- Requires expert supervision and operations.
- Materials cannot be stocked easily on the site.
- Good coordination and site organization are required.
- Large quantities of equipment (e.g. generators, lighting systems, and hoists) are required.
- The work must be continued in any weather
Application Of Slip Formwork
Construction Of Regular Core High Rise Structures
In the slip form construction technique used for high-rise building construction a reinforced concrete section is extruded vertically to create regularly shaped core structures and buildings.
Technique For Chimney Construction
The tapered slip form technique is used for constructing large vertical structures such as chimneys, cooling towers and piers. This technique allows for the creation of structures with varying wall thicknesses, shapes or diameters.
Construction Of Steel Tanks
The slip formwork construction method is a cost-effective way to build large cisterns for industrial and factory use.
Construction Of Water Towers
The slip formwork method is effective in creating high-quality walls for water tanks of various sizes including those with a capacity of thousands of liters.
