Formwork Blog

Archive for the ‘Formwork’ Category

Location: A Surfers Paradise High-Rise Construction Site, Gold Coast Australia

There is nothing more disappointing than stripping the formwork from columns or walls and discovering that there is absolutely no cover from the edge of the concrete to the reinforcement steel.

No Cover Concrete Column

Experienced formworkers will see this problem in advance and therefore ensure that the steel has the specified cover before closing up the formwork. This either means fixing it yourself, or organizing it to get fixed.

Obviously this is just another one of those dodgy high-rise construction projects on the Gold Coast where there is no quality control in place. Yes, there must be a Work Method statement in place, but it seems that on this job it is only good to wipe your arse with.

What is more disturbing to think about is how many of the columns on this 50+ storey appartment tower have the steel just 5mm under the surface of the concrete and therefore not detected? If it was not detected, is was probably never repaired.

Tip: before placing the Column Steel Cage onto the Column Starters, mark out all the columns on that floor in order to see in advance how much cover there is. Then, reposition any Starter Bars that are in the wrong position.

It is extremely rare to find Starter Steel in the correct position 100% of the time. Marking out the columns before the cage is placed will make it easier to reposition the starters into the correct position. In the long-run, this is quicker, cheaper and easier than making concrete repairs.

Location: Road Bridge – Port Adelaide South Australia

All the access scaffolding is now complete on this bridge column formwork. We are not quite ready for concrete yet because city council inspectors must give the okay first.

Column Formwork Almost Ready for Concrete

City Council inspectors will climb up the access scaffolding and make sure that the column forms and reinforcement steel inside the concrete forms are positioned according to the specifications on the plan. In most cases, the inspector will give it the go-ahead.

In my experience, the only times an inspector does not approve a concrete pour is when some formworker did not do what they knew had to be done. These formworkers hope that the inspector does not see that bit of steel too close to the concrete form, or that bar-chair that fell down to the bottom.

Or worse, sometimes a supervisor will instruct a formworker “not to worry about it”, then after the inspector picks it, they rush around like a freaking idiot trying to get it fixed

See the arial view of this formwork.

Location: Project Magnet – Iron Duke Mining Construction Site Whyalla South Australia

Thrust Block Formwork being constructed around slurry and water pipes.

Thrust Block Formwork

Timber scaffolding was used for access and work platform for inspectors, supervisors, concretors and formworkers.

Thrust Block Formwork with Timber Scaffolding

Location: Prominent Hill Mining Construction Site South Australia

Four concrete forms held together with Column-Clamps and held down with spaghetti nailed plywood. The 700 mm long bolts took a bit of work to cast in due to the extra reinforcement steel positioned exactly in the center of the pedestal.

Pedestal Formwork Ready For Concrete

This job was not as bad as the nightmare pedestal, but still took extra time because the formworkers had to reposition the steel in order to fit the bolts in.

Concretors Anthony and Nev Vibrating Pedestal Concrete

To ensure the correct heights, the concrete and bolt-top heights were established from a known benchmark with a Laser Level instrument and not by just measuring up from the foundation concrete.

Location: Road Bridge – Port Adelaide South Australia

Arial view of formwork for bridge columns. The concrete forms have been braced with concrete counter-weights and scaffolding has been errected in order to provide access for construction workers to complete the formwork and steelfixing and place/finish the concrete.

Braced Column Formwork with Access Scaffolding

Location: Prominent Hill Mining Construction Site South Australia

This four tread stair formwork is held together with 4 z-bar bolts, held down with pins at the front and wedges (to the structure) at the back, and braced with one timber on each side and two timbers at the back.

Four Tread Stair Formwork

Four verticle plywood cleats were also added to the back corners to prevent the rear concrete form from blowing out.

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

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

Sump Formwork with Ladder

You’ll notice that one of the center timbers is not used to brace the formwork, 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: Road Bridge – Port Adelaide South Australia

Formwork carpenters Lenny and Simon, and crane operator Craig position this concrete road barrier which will be used to anchor the bracing at one side of the column formwork. The brace on the other side will be anchored to the foundation.

Concrete Road Barrier To Brace Column Formwork

Location: Tugun Bypass Project Queensland Australia

This little formwork job was made quick and easy because there was plenty of Blinding to place the concrete forms and to brace off. The supervisor on this job asked how much Blinding we wanted, and to our amazement, enough was supplied.

Crash Barrier Foundation Formwork

Too often, formwork foundation jobs are made difficult and time-consuming when there is not enough concrete Blinding to secure the formwork. This usually happens when earth movers or supervisors do not consult with the formworkers and go on to blind to the exact size of the job according to the drawings.

I have had supervisors get the plan out and argue that the blinding is the right size because that is the size of the job on the drawing. On the other hand, experienced civil supervisors know to allow extra blinding not only for the concrete forms, but for bracing and holding-down as well.

Location: Road Bridge – Port Adelaide South Australia

The reinforcement steel and concrete forms being placed onto the bridge foundation by cranes at Port River Expressway bridge construction site.

Erecting Formwork For Bridge Columns

After all four concrete forms are placed, bracing, scaffolding and guardrails will be erected which will hold the column forms in a perfectly vertical position and allow access to the top of the forms.