Pins and wedges are often used to secure many types of timber formwork in order to prevent concrete blow out while at the same time define a nice straight “edge of concrete” line.

Pins and Wedges used to secure Formwork

How it works is you drill a hole into the slab, put a steel pin into the hole, then use a timber wedge to secure the formwork hard onto the previously installed fiberglass pins which define the edge of concrete.

Formwork Tip

Drilling a hole slightly larger than the pin allows for the pin to be extracted with little or no effort. For example, if you are using a 12mm pin, then the correct drill bit is 14mm. If you are using a 16mm pin, then drill an 18mm hole, etc.

To any observer, the pins and wedges in these photos look normal, however, there was extra labour involved to extract the pins because the holes were drilled the same size as the pin.

Close-up of Pins and Wedges Method

Bozo

Too often I see formworkers smashing a 12mm pin into a 12mm hole

What happens next is the pin cannot easily be extracted, so then an angle grinder, grinder blades, full face shield, generator, a crane to bring the generator, fuel for the generator, power leads, lead stands, RCD box, etc etc, must be organized just to cut the pins off.

On big mining and civil construction jobs, this “small” job could take over a day depending on the availability of all the above tools, plant and equipment. For example, the crane could be busy with much higher priority jobs, so you get no generator until the crane is free.

To me it makes much more sense to simply keep some extra drill bits in the drill box!

And Worse – On some jobs, the specifications require that the tops of those cut off pins be sealed with special epoxy resins which supposedly prevents corrosion of the slab.

This too however is incorrect because only the top of the pin is sealed which means the slab will eventually corrode due to the fact that there is steel with less than the required cover. In reality, the concrete around the pin should be jack-hammered down to the required “cover” and then epoxy sealed.

Conclusion

Taking short-cuts is not necessarily quicker!

• There is no future in being a fraud by creating the illusion of getting the job done quickly. This form of bullshitting only works on the gullible, and on those who have not been around the traps of the building industry.
• There is no freaking point in creating more work on the job.
• Credibility really goes to the formworker who takes the time to think ahead.

The above conclusions do not only apply to formworkers, they apply to all construction personnel.