Formwork Blog

Posts Tagged ‘Tips’

The photo below shows a formworker using a dodgy welding unit which was supplied by a plant hire company in Adelaide. What is wrong with this picture?

Dodgy Welding Unit

It is dodgy because the handpiece cable is only 1500 mm long! Therefore, the formworker must position this stinking, petrol-powered welder right next to himself so he can breathe in exaust fumes all day long.

When this issue was raised with management, the exact reply was: “That’s all they had”. That excuse does not make this safety issue go away! Send it back and tell the plant hire company not to send out unsafe, sub-standard equipment.

When requesting plant from a plant hire company such as this petrol powered welder, you should show that you know what you are talking about by telling them to supply long handpiece cables instead of just getting what CRAP they send you.

Why pay full price for sub-standard plant?

Don’t Be A Bozo

Don’t be a bozo and breathe in petrol exaust just because management cannot organize safe plant and equipment. You are better off getting fired than breathing in that shit for a day, a week or even months.

A common excuse construction supervisors give is “that’s all they had” or “that’s all we’ve got”. That’s is not your problem! Don’t be a bozo and use dodgy, unsafe plant and equipment.

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: Bolivar Water Treatment Plant SA

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.

Location: Port Adelaide South Australia

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.

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.

If you are building a mining industry website and are not ready to step through the web design mine field, then why not pick up some free mining web templates just to get your feet wet.

Mining Industry Website Templates

There is general web templates suitable for making small web sites and sales pages, plus there is also Wordpress themes so you can make your own mining blog.

Picking up some free website templates and getting your own web hosting is an inexpensive way to learn how to build your own web sites without paying a web designer if you have the willingness to learn.

Iron Duke Mining Construction Site South Australia

Avoid injuries by using a star picket driver to drive in star pickets when erecting safety barricades. Avoid back injuries by using the star picket extractor (also called star picket puller) to extract those star pickets from hard ground.

Star Picket Extractor and Driver

The ground was so hard at Iron Duke mining construction site that many of these star pickets bent over at the “bite point” before they would budge. Here is a star picket being extracted from hard rocky ground with the star picket extracting tool.

Star Picket Extractor in Action

Tip: That part of the star picket extractor that “bites” onto the star picket can be extended with a short chain which makes it much easier to use.

Star picket drivers and extractors can be hired from most good plant hire companies. They can also be purchased at all good stores which sell rural fencing supplies, and other good outlets which specialize in roadworks equipment.

I have been doing a bit of looking around Online at certain rural outlets for these items and have found that many Rural Supply outlets along with Plant Hire companies say on their web site “no photo available”. Hell, if they actually have the item for sale or hire, then there *is* a photo available, all they have to do is take a picture and upload it to their web site.

Tip: If there is no photo available, I think they are not a “good” store. You need to actually see what you buy or hire Online, else you’ll have to settle for what they send (which could fall short of your expectations).

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: A Construction Site In Sydney Australia on the 26th of September, 2008

Brand new (nine day old) 250 tonne Leibher Crane crashes through concrete floor on a Sydney Construction Site. I have not been told of any injuries or fatalities. If you know anything about this incident, your comments are welcome.

Photo 01 – Crane Crash 26-September-2008 Sydney

It would appear that the concrete floor did not have enough Back Propping underneath, and I cannot make out if large enough Sole Boards were used (if any) under the outrigger pads.

This concrete floor would also have a safe working load limit. If the crane exceeded the safe working load limit, the entire path where the crane traveled should be back propped underneath in order to increase the safe working load of the floor.

Photo 02 – Crane Crash

In most cases, a crane coordinator from the crane hire company usually sees things like this in advance and makes the necessary arrangements. At other times, experienced crane operators, riggers and doggers are competent enough to anticipate back-propping requirements.

Photo 03 – Crane Crash

The next photo reveals an outrigger pad with no sole-boards underneath it!

Photo 04 – Crane Crash

To me, Sole Boards are standard and should be placed underneath outrigger pads whenever the crane is setup. I was always told that outrigger pads can penetrate concrete floors and to always use sole boards underneath outrigger pads when setting up a crane.

Photo 05 – Crane Crash

Tip: Always position plenty of back-propping under a concrete floor directly underneath the outriggers, and always use big solid sole-boards underneath the outrigger pads in order to distribute the weight over a larger area.

Even when sufficient and correct back-propping is in place, outrigger pads have been known to penetrate concrete floors where sole boards have not been used.

Extra Sole Boards In order to distribute the weight over a larger area, it can be a good idea to stack two rows (instead of just one row) of hardwood sleepers under the specific outriggers which will be under the most load.

If you are ever unsure, ring the crane coordinator and demand an official decision.

Thanks for the photos Joe

An Invisible Beam Laser Level is used to determine an elevation from a known Datum Point. An Invisible Beam Laser Level is a handy tool used often by formworkers and concretors to set concrete heights, formwork heights and excavation depths.

Invisible Beam Laser Level, Tripod, Grade Pole, Receiver, and Grade Pole Level

Tip: Always calculate an elevation from an official Datum Point or RL (Reduced Level), not from some part of a building or structure which is “supposed” to be at a particular elevation.