Adelaide Northern Expressway Center Pier Steel Cage

The steel cage was pre-fabricated on site on top of the same formwork shuttering which will be used to form-up this 6 meter tall structure.

Construction Workers To Feed The Steel Cage Into The Base

Formworkers, steelfixers, riggers and supervisors work together feeding the cage into the base making sure that every steel bar in the cage is in the correct position in relation to the starter base steel.

Steel Cage Fixed Into Position

After the steel cage is fixed into position, the structure is ready to be enclosed by formwork shuttering. The finished concrete structure will be a narrow 600mm at the bottom and 1500mm at the top.

Starter steel for a 7.2 meter high concrete bridge pier which will support concrete bridge spans at Healslip Road Interchange Adelaide.

Center Pier Starter Steel

Formwork will be used to box the column just as soon as the rest of the steel is lifted into position by crane. This center pier will be 13m long, 600mm wide at the bottom and 1500mm wide at the top.

Here’s Joe surveying the exact locations of the bridge bearings which will be cast on top of the concrete bridge columns at Port River Expressway roadworks project.

Joe at Port River Expressway

Because the bridge spans will be sitting temporarily on timber packers, Joe also had to calculate the correct height of each packer for each corner of every column.

Not only that, each corner of each timber packer will be a different height because of the North/South and East/West bridge span angles.

Promise not to leave you up there when we go to lunch Joe

After each column concrete pour, the column formwork gets stripped down to be cleaned with high pressure water blasting and grinding with a wire wheel to remove all the slurry.

Cleaning Column Formwork

After cleaning, a special oil is applied to the forms which ensures they will strip off easy next time, and also helps provide a nice smooth finish on the concrete.

Here is the concrete bridge columns resulting from the use of this column formwork. The bridge will eventually span accross one railway track and one busy main road.

Concrete Bridge Columns

Formworkers are now almost ready to cast in the bridge bearings on top of these columns which will support the steel bridge spans. But first, surveyors must mark out the exact location of the bridge bearings.

Alternative View of Concrete Bridge Columns

Instead of scaffolding, elevated work platforms (EWP’s) will be used to gain access to the column tops. For safety, tube and coupler guard rails will be errected on top of each column before any other work begins.

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.

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.

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

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

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.