Formwork Sizes
time2018/07/08
The size of these tables can vary from 70 to 1,500 square feet (6.5 to 140 m2). There are two general approaches in this system:
Crane handled:
this approach consists of assembling or producing the tables with a large formwork area that can only be moved up a level by crane. Typical widths can be 15, 18 or 20 ft. or 5 to 7 metres but their width can be limited, so that it is possible to transport them assembled, without having to pay for an oversize load. The length might vary and can be up to 100 ft. (or more) depending on the crane capacity. After the concrete is cured, the decks are lowered and moved with rollers or trolleys to the edge of the building. From then on the protruding side of the table is lifted by crane while the rest of the table is rolled out of the building. After the centre of gravity is outside of the building the table is attached to another crane and flown to the next level or position.
This technique is fairly common in the United States and east Asian countries. The advantages of this approach are the further reduction of manual labour time and cost per unit area of slab and a simple and systematic building technique. The disadvantages of this approach are the necessary high lifting capacity of building site cranes, additional expensive crane time, higher material costs and little flexibility.
Crane fork or elevator handled:
Formwork tables in use at a building site with more complicated structural features
By this approach the tables are limited in size and weight. Typical widths are between 6 to 10 ft or 2 to 3 meters, typical lengths are between 12 and 20 ft or 4 to 7 metres, though table sizes may vary in size and form. The major distinction of this approach is that the tables are lifted either with a crane transport fork or by material platform elevators attached to the side of the building. They are usually transported horizontally to the elevator or crane lifting platform singlehandedly with shifting trolleys depending on their size and construction. Final positioning adjustments can be made by trolley. This technique enjoys popularity in the US, Europe and generally in high labor cost countries. The advantages of this approach in comparison to beam formwork or modular formwork is a further reduction of labor time and cost. Smaller tables are generally easier to customize around geometrically complicated buildings, (round or non rectangular) or to form around columns in comparison to their large counterparts. The disadvantages of this approach are the higher material costs and increased crane time (if lifted with crane fork).