In the realm of modern construction, slip formwork, also known as slipforming, emerges as a dynamic technique for casting concrete structures. This method involves a continuous upward movement of the formwork while concrete is poured, creating a seamless construction process. Let’s delve into the details of this innovative construction approach.
The slip formwork process is characterized by a constant upward motion of the formwork, with concrete being poured continuously until the desired casting length is achieved. It is crucial to closely monitor the pouring and setting rates of concrete to ensure that the formwork ascends at an appropriate pace. This method relies on the rapid setting and cooling properties of concrete for optimal efficiency.
Slip formwork finds its niche in the construction of unconventional structures such as cooling towers, chimneys, silos, as well as in roadway and bridge construction. However, it’s essential to note that this method is not universally applicable and is generally employed for structures exceeding a height of 16 meters.
The slip formwork system consists of several key components that work in tandem to facilitate the construction process.
1. Vertical Forms : Vertical forms, crafted from materials like metal, wood, plywood, or reinforced plastic, serve the primary function of shaping the concrete.
2. Wales : Wales play a crucial role in securing vertical forms in place while providing support for scaffolding and other platforms.
3. Yokes : Yoke legs lift and support the entire structure, safely transmitting lifting forces from jacks to wales. They also connect with beams, scaffolding, and other supporting platforms.
4. Jacks and Jack Rods : Jacks, mounted on jack rods, provide the necessary lifting force for the entire slip form system.
Different types of slip formwork cater to various construction needs.
1. Vertical Slip Formwork : This technique relies on the extrusion concept, utilizing hydraulic jacks to achieve continuous vertical sliding motion during the concreting process.
2. Horizontal Slip Formwork : Ideal for pavement and traffic separation walls, this method involves laying, vibrating, and settling concrete while the form gradually moves forward.
3. Cantilever Jump Form Method : Used for climbers independent of cranes, this method offers a self-climbing formwork system for walls, columns, supports, and floor beams.
4. Egg Shaped Slip Form System : Adaptable to any geometric shape, this system allows curvature adjustments independently on each side of the wall, ensuring optimal working conditions.
5. Canonical Slipformwork : Facilitating monolithic construction with variable cross-sections, this method employs horizontally movable formwork structures mounted on hydraulically adjustable tapering elements.
Slip formwork offers numerous advantages in the construction process:
Despite its benefits, slipform construction has its drawbacks:
To ensure safety during slipform construction, several features must be implemented:
