Flexible formwork

This invention relates to a flexible and collapsible formwork, particularly for use when casting submarine areas as well areas above water level, e.g. the bottom of ferry landings, the external side of moles, rock fills, fill dams for power plants, encapsulating wrecked ships and other objects desirable to shield due to environmental purposes, and with a number of other casting works.

The object of the invention is to provide a simple and handy formwork for the above-mentioned purposes and which may be produced on a manufacturing scale.

The object is achieved through the features as defined in claim 1 below.

An embodiment of the invention is diagrammatically shown in the attached drawings, in which:

Figure 1 shows a perspective view as seen obliquely from above of a pre-fabricated formwork;

Figure 2 shows on a larger scale a section through the formwork;

Figure 3 shows a formwork joint;

Figure 4 is an end view of a formwork placed on a rock fill, partly above and partly beneath water, and where the formwork is filled with concrete.

In the drawings, reference numerals 1 and 2 respectively denote a top cloth and a bottom cloth of PVC or another suitable cloth material having a sufficient flexibilty and strength to take up the loads to which the formwork is subjected. The top cloth 1 and the bottom cloth 2 form respectively an external and an internal formwork. Top cloth 1 and bottom cloth 2 are welded together along the edges. They may also be joined by means of zip fasteners 3, as shown in figure 3. Intermediate the two cloths 1 and 2, a number of spacers 4 are placed, so that the formwork forms a substantially flat bag, a formwork bag 1,2. On the outside thereof, this bag is provided with a number of mutually crossing reinforcing straps 5, and a spacer 4 is disposed through each of the crosses formed by the reinforcing straps 5. The spacers 4 may be rigid or flexible.

In the embodiment, the spacers 4 consist of synthetic fibre bars each having two fixed bracket projections 6, securing a correct distance between the cloths 1 and 2, the inner side of the cloth 1 respectively 2 resting against the outside of the bracket projection 6 of the spacers 4, while a nut 7 with a washer 8, at each end of the spacer 4, clamps the reinforcing straps 5 firmly against the cloth 1 respectively 2 as shown in figure 2.

Where edges of the cloths 1, 2 are joined by means of zip fasteners 3, a number of extra reinforcing straps 9, anchored in at least one row of spacers 4 at each side of the zip fastener, has been placed.

At exposed positions, each single formwork bag 1,2 is suitably equipped with reinforcements 10 and, moreover, with loops 11 for towage. Moreover, each single formwork bag is equipped with at least one coupling stub 12 for

the filling of concrete into the bag, and a number of venting valves 13 in order to allow air to escape as concrete is being filled into the formwork bag 1,2.

Prior to the top cloth's 1 attachment to the bottom cloth 2, the formwork bag 1,2 may be provided with a reinforcement 14 consisting of e.g. wire mats and/or usual steel reinforcement. To this end, the spacers 4 are provided with a number of holes 15 for the attachment of binding cords 16 in order to keep the reinforcement in position.

The formwork bag 1,2 may be produced in different sizes and with different shapes and profiles, dependent on the field of application and, by means of zip fasteners, any number of formwork bags 1,2 may easily be built together to form a formwork of any size.

As it appears from figure 4, the formwork will, due to its flexibility, adapt itself to the substrate such that the latter becomes well bonded, and such that the whole forms a good total structure.

It is appreciated without saying that the top cloth 1, possibly also the bottom cloth 2, at appropriate places might be formed with one or more bracket projections which, subsequent to casting, will form a suitable base for e.g. quai works or other structures.

The formwork according to the invention has generally a very good ability to adapt itself; it may be used for many different purposes; it may substantially be pre-fabricated; it may be rolled together and, thereby, easy to transport; it is easy to position, and specially trained workers are not required in order to operate the formwork.

Subsequent to the casted concrete's, the upper parts of the formwork bag may, of course, be removed if so desired.