Building with concrete has a few different options available, and knowing how to choose the right option for your project can save you time and money. Hence, this article will explain the basics of slipform and jump work, and indicate when it is recommended to use each one.
Although slip forming sounds very similar to slipform kerbing, they are in fact quite different. Slip forming is a way to economically construct high buildings or paved surfaces quickly. Slip forming is much more complicated and difficult to get right than other concrete construction methods, but for high buildings it is the most sensible option.
Slipform is good when the height of the construction is likely to be tall enough or wide enough to justify the complexity and cost of setting up a slipform construction job.
Work on slipform sites requires 24 hour operation, and pouring must be taking place continually. Because of the requirement for workers to operate outside of regular working hours, including weekends, the costs are higher than jump form construction.
The bigger the job, the more suited it is to the slipform construction method. Some people suggest that the minimums for considering slipform to be viable are either a height of 60m (213') or a diameter of 20m (65').
The advantage of slipform construction is that it yields very high strength and does not contain joins. It's most useful for structures that need that kind of strength and monolithic structure. For example, silos, dams, and bridge towers are all objects that might be candidates for slipform construction methods.
Jump work, also known as climbing form work, is suited to a wider range of construction projects and is far more commonly seen than slipform construction.
Work progresses in stages, (in a climbing fashion) with the building completed layer by layer from preformed concrete units. In rare cases there may be direct pour on site, but always in small modular sections and never in a continuous pour as is the case with slipform construction.
While work can continue around the clock, it doesn't need to. Therefore, most construction sites, unless they are on a tight deadline, don't operate outside regular working hours. Progress may then be slower, but the cost is lowered in terms of the amount spent per work hour.
Scaffolds and cranes allow the work to progress, step by step, with the scaffolding being moved upward as each successive layer of construction is completed. This means buildings constructed in this way are always built from the bottom up, and work must progress in a linear way. Higher sections can't be worked upon at all until the lower sections are completed.
Because the majority of construction is composed of modular units, work can be performed very efficiently, and it is easy for workers to be trained to carry out their tasks. Safety is also generally better on these construction sites than on slipform sites.
Finally, errors on a jump work site are relatively easy to correct, whereas on a slipform site they are not. Equipment malfunctions on a jump work site are inconvenient, whereas on a slipform site they can be disastrous.