Formwork

FORMWORK FOR COPINGS

A free-standing wall which is not part of the building (not under the roof) needs to be protected against rain, which otherwise might penetrate at the too of the wall and damage it. This is done by adding a "coping" at the top of the wall.

SADDLE-BACK COPING:

This is placed on top of the wall as shown in Fig. 1. The formwork for the coping is shown in Fig. 2. The drip or throating is made by setting two pipes or smooth iron rods in the wet concrete. The correct position can be assured by using wooden spacers tied to the pipe (Figs. 2 & 2a).

A second way of making the coping is shown in Fig. 3. A line is fixed at the height of the ridge aad the surfaces are shaped with the steel float. The drip is made by fixing half-round beads onto the soffit board of the formwork (Figs. 3 & 3a).

SPLAYED COPING:

The splayed coping in Fig. 4 can also be made in two ways, in a fashion similar to the saddle-back coping above (Figs. 5 & 6).

FORMWORK FOR PILLARS

The formwork for a concrete pillar is shown in Fig. 7 below.

FORMWORK FOR SLABS

Fig. 1 shows an example of formwork for a slab. Paper should be set underneath before the concrete is cast.

Fig. 2 shows an example of the formwork for a slab with an opening in it.

GENERAL HINTS FOR FORMWORK

Use good, straight-grained wood.

Make a sketch of the formwork before you start to make it.

Design the formwork so it can be easily removed from the piece after curing,

Use enough supports and braces to make the formwork rigid and strong.

Be aware that the wood swells when it is in contact with the wet concrete.

If the concrete will not be plastered later, plane the formwork members smooth where they are in contact with the concrete.

Do not overnail the structure, and fix the nails so that they can be taken out easily.

Oil the form lightly where it is in contact with the concrete.

For precast members, put the form on the ground in a level spot, and put paper underneath It (old cement bags).

Remove the formwork only when the concrete has hardened sufficiently (the time depends on the member which is cast).

Be careful not to dumage the edges and corners of the concrete piece when you remove the forsnwork.

Clean off the formwork with a steel brush and take out all nails when you finish.