Slipform

modern technique of framework

1. SLIP FORM CONSTRUCTION A STUDY OF ITS CONSTRUCTION TECHNIQUES PRESENTED BY : RAHUL BHARDWAJ B. ARCH 7 TH SEM NIMS SCHOOL OF ARCHITECTURE AND PLANNING

2. INDEX Introduction Slip form jump form RAHUL BHARDWAJ B.ARCH 7TH SEM process efficiency Safety Sustainability features Consideration Introduction Procedure Types of slip form Advantage Precautions Application of slip form

3. INTRODUCTION Slip form construction, or continuously formed construction, is a construction method in which concrete is poured into a continuously moving form. Basically, this method involves the continuous placing of concrete in a shallow mould having the same plan as the building to be constructed. This rigid mould , or "slip-form" as it is called, forms the working deck which is jacked slowly upwards at a controlled rate until the required elevation is reached. RAHUL BHARDWAJ B.ARCH 7TH SEM

4. INTRODUCTION : Method of vertically extruding a reinforced concrete section and is suitable for construction of core walls in high-rise structures – lift shafts, stair shafts, towers. The formwork rises continuously, at a rate of about 300 mm per hour, supporting itself on the core and not relying on support or access from other parts of the building or permanent works . Allows for the continuous pouring of concrete into walls of a structure and only stops when the full required height of the structure has been reached . The height of the formwork is designed in such a way that while the top of the formwork is being filled by concrete the lowest layer of concrete poured earlier has already gained an initial set. When the formwork is moved upwards the concrete that is then exposed remains firm. CHEUNG KONG CENTRE RAHUL BHARDWAJ B.ARCH 7TH SEM 2-SLIPFORM TECHNOLOGY

5. PROCEDURE : Assembly can only start once the foundations are in place and the wall starter is in correct alignment . Slip form shuttering is aligned with the help of yokes . Horizontal crossbeams connect these yokes . Hydraulic jacks are attached to these crossbeams for simultaneous upward movement . Height of the slip form ranges from 1.1 to 1.5 meters. Yokes and crossbeams also used to support the working platform. Structure should be rigid and shape maintained at all times . Make sure there is no lag or else it prevents the structure from free upward movement It is also possible to reduce wall thicknesses as the construction gains height and arrangements have to be made in the slip form structure that will enable such reduction at regular intervals. RAHUL BHARDWAJ B.ARCH 7TH SEM

6. 1- VERTICAL SLIP-FORM 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. Together, the concrete form and working platform are raised by means of hydraulic jacks. Generally, the slip-form rises at a rate which permits the concrete to harden by the time it emerges from the bottom of the form. RAHUL BHARDWAJ B.ARCH 7TH SEM TYPES OF SLIP-FORM CONSTRUCTION

7. 2- HORIZONTAL SLIP-FORM In horizontal slip forming for pavement and traffic separation walls, concrete is cast, vibrated, worked, and settled in place while the form itself slowly moves ahead . This method was initially devised and utilized in Interstate Highway construction initiated during the 1950s . RAHUL BHARDWAJ B.ARCH 7TH SEM

8. Slip form methods of construction can also be adapted to horizontal structures and are used for paving, canals, and tunneling . The technique is more in use for structures that have continuous walls like silos , chimneys, and piers for very tall bridges . It has also been successfully used for construction of buildings, although this requires the manner of leaving inserts for openings like doors and windows to be decided well in advance, as well as also any necessary inserts to support floor slabs after the walls are constructed. RAHUL BHARDWAJ B.ARCH 7TH SEM HORIZONTAL SLIP FORM :

9. RAHUL BHARDWAJ B.ARCH 7TH SEM 3-TAPERED SLIP-FORMING Slip-forming is also used in the construction of conical chimneys, cooling towers, piers and other tall concrete structures involving constant or changing thicknesses in walls, diameters and/or shapes. A form is used with sections which overlap so that one gradually slides over the other. This is commonly done in chimney construction but it is not satisfactory for architectural concrete because the lap shows. While the tapered slip-forming process is similar to that used on the standard slip-forming, it requires greater attention, contractor experience and expertise ensures the success of such projects.

10. ADVANTAGES: A major cost of concrete structure construction is the required formwork to retain the concrete till it can be safely de-shuttered and be able to support itself and other imposed loads. The formwork needs to be continually removed to newer locations and then re-erected. Continuous use of manpower and lifting equipment like cranes. In the case of slip form building, the formwork is erected only once and remains intact until the entire structure is completed . Great reduction in the cost of formwork as well as time saving for re-erection. Cost effective The reduction in the movement of formwork and workers also leads to far more safe working conditions that also make it a major advantage. RAHUL BHARDWAJ B.ARCH 7TH SEM

11. PRECAUTIONS Concrete is continuously protected against loss of moisture and rapid temperature changes for 7 days Unhardened concrete is protected from rain and flowing water Prevent plastic shrinkage Plastic cracks are filled by injection of epoxy resin. RAHUL BHARDWAJ B.ARCH 7TH SEM

12. APPLICATIONS OF SLIP-FORM CONSTRUCTION Slip-form construction is used for tall structures, such as towers, buildings, and dams, as well as horizontal structures, such as roadway barriers. It enables continuous, non-interrupted, cast-in-place joint-less concrete structures which have superior performance characteristics over construction methods using discrete form elements. Slip forming relies on the quick setting properties of concrete, and requires a balance between quick-setting capacity and workability . Capital Gate Tower, Abu Dhabi King Abdul-Aziz Airport Inn Canal, Germany RAHUL BHARDWAJ B.ARCH 7TH SEM

13. 3-JUMP FORM: Generally , jump form systems comprise the formwork and working platforms for cleaning/fixing of the formwork, steel fixing and concreting . Jump form, often described as climbing form. It is suitable for construction of multi-floor vertical concrete elements in high-rise structures, such as shear walls, core walls, lift shafts, stair shafts and bridge pylons . It is a highly productive system designed to increase speed and efficiency while minimizing labor and time. RAHUL BHARDWAJ B.ARCH 7TH SEM

14. PROCESS EFFICIENCY : Fast construction can be achieved by careful planning of the construction process. Crane availability is critical for normal jump form. Self-climbing formwork cuts down the requirement for crane time considerably. By allowing the crane to be used for other construction work this may reduce the total number of cranes needed on site. The formwork is independently supported, so the shear walls and core walls can be completed ahead of the rest of the main building structure. This can help to provide stability to the main structure during its construction and can have the beneficial effect of taking the jump form core off the project critical path. RAHUL BHARDWAJ B.ARCH 7TH SEM

15. SAFETY : Working platforms, guard rails, and ladders are built into the completed units of market-leading formwork systems. Complete wind-shield protection on platform edges is also possible. Self-climbing formwork systems are provided with integral free-fall braking devices. The completed formwork assembly is robust and provides a stable working platform. The reduced use of scaffolding and temporary work platforms results in less congestion on site. The setting rate of concrete in those parts of the structure supporting the form is critical in determining the rate at which construction can safely proceed. The repetitive nature of the work means that site operatives can quickly become familiar with health and safety aspects of their job. Formwork suppliers provide materials and resources to help train the labour force. RAHUL BHARDWAJ B.ARCH 7TH SEM

16. SUSTAINABILITY FEATURES : The formwork system is easy to clean and reuse with little formwork waste generated compared to traditional formwork . Climbing formwork systems offer simplicity, safety and cost effectiveness for certain high-rise building structures . The repetitive nature of the work, combined with the engineered nature of the formwork, allows fine tuning of the construction operations, which in turn leads to minimal concrete wastage . Many repeated uses of formwork are possible before maintenance or replacement is needed, the number of uses depending on the quality of the surface finish of concrete specified. RAHUL BHARDWAJ B.ARCH 7TH SEM

17. SUMMARY • Slip form construction is a construction method in which concrete is poured into a continuously moving form. • There are two types of slip-forms; vertical and horizontal . • Slip-form construction consumes very less time but requires careful planning of construction process to achieve high production rates. • Due to continuous concrete pouring in slip-form construction it produces better concrete joint less and watertight structures. • Slip form systems require a few but highly skilled workforce . • Slip-forming is also used in the construction of tapered structures involving changing thicknesses in walls, diameters and/or shapes . RAHUL BHARDWAJ B.ARCH 7TH SEM

18. RAHUL BHARDWAJ B.ARCH 7TH SEM REFFERENCE WIKIPEDIA.ORG SLIDESHARE.NET THECONSTRUCTOR.ORG WWW.CONCRETECENTRE.COM fac.ksu.edu.sa/sites/default/files/7- _ slip - form _ construction . pdf