Formwork Blog

Posts Tagged ‘Walls’

Location: Northern Expressway Adelaide SA

When Z-Bars become difficult to extract because concrete slurry has leaked into the conduit, it may be necessary to make a heavy duty Z-Bar extracting tool.

Z-Bar Extractor

Simply cut a notch in the plate of a Prop-Inner, Screw-Jack or similar item. The notch should be slightly bigger than the diameter of the Z-Bars being extracted.

The length of the Prop Inner tube should be cut down to a manageable length while keeping in mind that the longer the tube (handle) is, the more effective it will be for extracting stubborn Z-Bars. (The longer the handle, the heavier the tool.)

Z-Bar Extractor In Action

To use the Z-Bar Extracting tool, remove the Z-Bar plate (washer) and replace only the nut. Then simply slide it along the Z-Bar towards yourself smashing the nut.

The photo above shows us using the Z-Bar Extractor to pull out a stubborn 4 meter long, 25 mm thick Z-Bar from a poured concrete pier. The Z-Bar Extracting tool made light work from what would otherwise have been one of those crappy never-ending jobs.

Pitfalls To Avoid

Important! Don’t be a bozo and smash your fingers into something while pulling back with the Z-Bar Extracting tool! Look around before you start smashing.

Tip: The length of the handle should be determined by your surroundings. For example, you would not have a 2400mm handle if you were working from a tight scaffold. You would cut it down to say 900mm – 1500mm max.

Tip: Using the Z-Bar Extracting tool on Z-Bars that are not so stubborn is also a good idea because it will reduce the number of times the ends need to be ground-down in order for the nut to fit properly.

Smashing Z-Bars out the regular way with a hammer will burr the ends, increase servicing requirements and produce down-time when someone goes to screw a nut onto a burred Z-Bar.

Location: Prominent Hill Mining Construction Site South Australia – Weigh Bridge Section

Timber used to brace internal sump formwork at Prominent Hill weigh bridge.

Weigh Bridge Sump Formwork

You’ll notice that one of the center timbers is not used to brace the concrete forms, rather, it is used to support the yellow ladder treads. Extra z-bars and timbers that support the external forms are also just visible in the above photo.

Sump Formwork Ladder Support

The vertical timber holds the ladder treads firmly against the plywood while the treads are wired to a nail (not visible) keeping the treads horizontal.

Sump Formwork Ladder (internal view)

You’ll also notice that there is two pieces of ply used in the center of the ladder tread instead of one which makes easy work when it comes to stripping. On the other hand, if one piece of ply is used for these types of formwork, it is a time-consuming nightmare to strip.

Location: Prominent Hill Mining Construction Site South Australia – Weighbridge Section

I bumped into a construction worker friend of mine recently at Whyalla shopping center who said he just had some formwork blow-out during a concrete pour. I asked him if he used a Bedlog to brace-off the concrete forms, and it turns out he did not.

Whenever you suspect that the pressure on your concrete forms will be more than your average driveway slab, or you are having difficulty maintaining a straight line, it could be a good idea to consider placing a Bedlog down in order to have something solid to brace your formwork off.

Formwork Carpenter Laying Down a Bedlog

A Bedlog (also known as a Dead-Man) is used to secure both walls and slabs and can be used on even and un-even ground. Use the Bedlog to push and pull your concrete forms into a perfectly straight line and hold it securely in position.

Concrete Wall Forms Braced With Bedlog

In the photo above, only the top of the concrete forms is braced onto the bedlog because the bottom of the forms is inside an excavation. If the entire job was on level ground, the bottom of the forms would also be braced back to the bedlog.

Bedlog Secured With Pins And Wire

Bedlog vs Pins Only

A Bedlog enables you to push/pull and secure the concrete forms into a nice straight line while bracing with pins/pegs only allows you to push. This allows you to totally eliminate any dog-legs while eliminating all movement from the formwork.

Using only pins/pegs can fail and cause the concrete forms to blow-out while a Bedlog is much stronger and therefore more reliable.

Using a Bedlog enables you to erect your formwork and walk away. What this means is that in most cases you will not have to be nearby “watching the concrete pour” because you are worried that your formwork will collapse under pressure.