The Rail Track was removed and the Slab demolished after the crane passed through. There is 6 Ball Mills so this process was done several times.

Click the images for a larger more detailed picture.

Bolt Template

The bolt template is made from steel in order to support the weight of the bolts. The template must have the Center Lines scribed into it in order to place it into the correct position.

The template is clamped onto aluminium formwork beams. The beams are secured onto the formwork shutter with a timber and Z-Bar holding-down assembly.

The center of the bolts was marked onto each side of the forms and a string line was stretched across.

Then we used either a plumb bob, or spirit level to align the string line with the scribed centers on the template.

Doing this positions the bolts pretty close, but not close enough for a mining job. Later surveyors will come and check the bolt centers and each bolt position.

The total weight of the bolts is 480 kg. It is essential to get the assembly positioned as close as possible so that it makes it easier to lever into a spot-on position with the surveyer.

The Bolts

For safety reasons, we found it necessary to lift these bolts in one at a time with a crane.

Tolerance Tubes

After the bolts are in, polystyrene Tolerance Tubes must be added to the bottom of the bolts at the correct height. The height was established and scribed onto the formwork shutter, then transferred onto the bolts with a spirit level.

Adding the Shear Key and Bottom Template

The Shear Key was added next. After that the bottom template made from form ply was added.

A hanging assembly made with timber and z-Bars was used. The Z-Bars were used to wind the Shear Key up until it buts up tightly into the Spreader Bar timber holding it firmly in position.

The Z-Bars are also used to “Crack’ the Shear Key after the concrete is poured. Crack the Shear Key while the concrete is soft (Don’t wait till the next day).

Concrete Finished

One down, 7582 to go Personally, I’d rather be fishing.

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Obviously you would not cut these down to size from a brand new length, but because cutting Z-Bars to size is common, there will always be lots of Off-Cuts which can be used for this.

Z-Bar Pin And Wedge

To use the pin and wedge system, you must first have location pins on the inside of the formwork. This will prevent the formwork going over the line when the wedge is hammered in. These location pins are usually some thin steel around 10mm, but some projects do not allow steel so fiberglass pins are used.

Next, drill a hole larger than the Z-Bar to allow for a pretty loose fit. You’ll know the hole is too small if you have to use a hammer to drive them in.

Ensure there is a nice gap for the wedge to fit in. I often use a piece of plywood as a packer between the forwmwork and the drill bit. This leaves a gap of around 20mm which is heaps for a wedge.

After the hole is drilled, tap the wedge in until the formwork hits the location pin on the other side. Then secure the wedge with a nail wrapped around the pin to ensure the wedge stays in while the concrete is being vibrated.

Z-Bar Pin And Wedge

Using Z-Bar pins and wedges ensures that the formwork stays in the correct position while the concrete is being poured, plus, it’s fast and is easy to strip.

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Pedestal Base Formwork

After the base concrete is poured, the formwork is stripped leaving the pedestal steel starters exposed. After the steelfixers fix the remaining steel to the starters, it is time to assemble the pedestal formwork.

Typical Pedestal Base

On this job there are many pedestals this particular size (1200mm H x 1100mm x 1100mm) so we are using conventional timber and plywood formwork along with prefabricated steel forms.

Example #1 – Conventional Pedestal Formwork

One box composed of four small formwork shutters held together with z-bars and strong-backs.

Conventional Pedestal Formwork

Example #2 – Prefabricated Steel Pedestal Formwork

One box composed of two steel forms held together with nuts and bolts.

Prefabricated Steel Pedestal Formwork

There is several of these steel forms on this job because there are lots of these typical (exactly the same) pedestals.

Prefabricated Steel Pedestal Formwork

A closer look at the bolt template, bolts, tolerance tubes and shear key.

Pedestal Bolt Template and Shear Key Formwork

Here is the finished pedestal. If you look closely, you will notice that the shear key formwork is yet to be stripped.

Finished Pedestal

The pedestal formwork will be assembled after the concrete base is poured and set.

Dimensions: 2000mm x 2000mm wide x 1200mm high.

Precasting six cone shaped concrete structures 2 at a time for the Adelaide Aqua Port Stanvac Desalination project.

Scaffolding

The 400 mm thick bases for the concrete units was poured first and the 2600 mm cone shaped section will be added on top. After the bases are poured, the scaffolding is added to enable steel fixing, formwork erection and pouring of concrete.

Tube and Fitting Scaffold

Internal Formwork

The internal formwork is 1800 mm diameter (not cone shaped) which includes 2 x 6mm plywood layers bent into shape and screwed into the vertical timbers one layer at a time.

Cone Formwork Internal

External Formwork

The external formwork below is cone shaped. It will also be skinned with 2 x 6mm plywood layers. It will take a bit longer to screw the ply to the external formwork because of all the extra cutting into the cone shape.

Cone Formwork External

Below we see the skinned external formwork being added to the structure in 2 parts. There is no way this formwork would fit around the steel in one piece, so we split it in half, lifted it in two crane lifts and joined it all up in position.

Cone Formwork

Finished Precast Concrete Unit

Below we see the finished 30 tonne pre-casted concrete unit. It will later be placed on a barge with the other 5 units and floated out to Port Stanvac Desalination Project.

Cone Shaped Pre Cast Concrete

Plain old circular formwork is a bit easier than cone shaped formwork.

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.

While this slab formwork “may” hold the concrete, it could be done a bit more professionally by using plywood rips and a bedlog to straighten the edgeform instead of wire. I can’t believe the formworkers that did this job recon it was ready for concrete.

Dodgy Formwork

Using wire back to a single pin to pull the formwork into line is dodgy and time-consuming because the pin can flex (or the wire can break) and put a “dog leg” in the formwork.

Dodgy Formwork Braced without a Bedlog

Tip: If it is important to have nice straight formwork (it should be), always use a bedlog. A bedlog enables you to push and pull the formwork into the exact position, secure it properly and “walk away”.

Even if it is not important to have nice straight formwork because the crooked concrete will “never be seen”, it is not a good look to have dog-legs in a concrete slab. By the way – It will be seen before it is never seen. It will be seen by bosses and inspectors.

Here’s another thrust block formwork job we had to do, but this time it was below the water table which means that water would be continually pouring into the job the whole time.

Thrust Block Excavation

Imagine arriving at this job and they say they want a couple of thrust blocks around these pipes, and they want it quick coz it’s “just a couple of thrust blocks”

Pumping the Water Out

Not only that, Des had to be very careful while digging out this watery goop to avoid damage to the fiber optic telecomminications and electrical cables while the pump pumps water out all day long. Des named this job The Swamp Monster

Concrete Thrust Blocks (Pump Still Pumping)

Finally the job is done and the Concrete Thrust Blocks are in position. The formwork for this job was almost the same as this other thrust block formwork we did.

This is the formwork which will be used to cast the bridge bearings into position on top of the concrete columns. Silicon sealer was used to completely seal the formwork in order to stop any grout leakage, while at the same time holding the formwork securely in position.

Bridge Bearing Grout Formwork

You’ll notice that the original holes that were voided out during the concrete pour have been filled in with grout and new holes have been core-drilled. Why? ..

This happened because either the wrong hole centers were supplied to the formworkers, or a different size Bearing Pad was supplied in the end. Every column top had to be core-drilled in this way

You’ll also notice that the surface has been scabbled. This is specified as part of the job to ensure that the grout bonds properly to the concrete.

Tip: Don’t try and get away without scabbling the concrete if instructions were not given to do this job. Treat it as part of the job and do it without being told.