Re-bar and mould oil.

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We've been lashing the re-bar with mould oil on a job at the moment and some areas form a critical part of the structure.
Is this acceptable?
Many Thanks.
 
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We've been lashing the re-bar with mould oil on a job at the moment and some areas form a critical part of the structure.
Is this acceptable?
Many Thanks.
Is it acceptable.. well no is the simple answer.. clean it or replace the rebar.. either that or get specific written instruction from the SE
 
Are you an SE Static?
One of the guys was just saying today he was almost put off site on another job for spraying the re -bar. :(

The current shuttering structure we've assembled has taken a week and applying the mould oil perhaps tomorrow or the next day will inevitibly result in some sections of the re-bar being sprayed.
We are hoping to reduce this down to two days for subsequent pours so spraying before placement of the shutter will happen. :D
On good straight walls we never spray the re-bar. Pours are everyday.
This job has been a real pain. :(
 
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Are you an SE Static?
Yes.

Hmm.. first thought you had painted the rebar in the oil already before fixing.. still think you should get confirmation that the SE is happy with some splashes.. but i dont know how critical your critical bits are
 
It looks something like this.
We have a 5cu/m pour tomorrow morning inside the dotted lines if you can see it..
There's about another 16 pours like this. :D
We were awaiting the arrival of suitably rated special high tensile steel (or so we thought) holding bolts for the rear strut of the roof trusse which will be anchored into the concrete.
They arrived today a week late.
Anyway what we have been given is 25mm threaded bar with no rating , (Probably brittle chinese dirt) that we could have gotten hold of in the local hardware store.
Were none to happy but the roofing engineer and SE have given the go ahead for their use. :(
So on their heads be it if anything goes wrong!
Its a small football grounds with the seated capacity on the east side being increased from 5000 to 20,000 people.
 
Thats some cantilever!

I'm suprised to hear that standard stud is ok as a replacement for HT holding down bolts. Especially if the stud is no larger than the spec HD bolts. Get it in writing and make sure BCO sees it.
I assume you'll use bolt boxes and washer plates, it gives movement with the full embedment depth.

Nice job!
 
Bloody chinese plasticine.. glad to see someone else doesnt like it..
Looks like quite an interesting job..
 
Why the hell would you want to treat the rebar with mould oil!!!

Mould oil is for treating the internal timber faces of the formwork so that the concrete does not adhere to the formwork and makes removal of the formwork once the concrete has cured that much easier.

Surface corrosion of the rebar is not a problem, especially when its encased in concrete, I would suggest that you get hold of some degreasing agent and try and undo what you have done!

You live and learn and in this instance your on a steep learning curve!

Regards
 
Hi More woes!!

Following on from my earlier comments:

I cannot believe that the SE has condoned the use of anything less than HT steel - The canopy is designed as a cantilevered structure and the HT steel bars between the roof structure and the mass of the concrete to the new section of the stands (which you are about to pour) will act in tension to hold the roof canopy in place - ordinary mild steel will not be capable of withstanding the tensile loads during the design life of the building and what with your 'mould oil' - the finished canopy is going to be a disaster waiting to happen - maybe not overnight, but eventually something will fail and a whole section (if not all) of the roof will come crashing down onto the terraces below! Hopefully, for everyone's sake there will not be a public audience in the stands at the time!


You may wish to pass these and the earlier comments that I have made on to the Principal Contractor and Client, as you will all likely be in the 'dock' if you continue down the current path!
In all honesty - I cannot believe that a group of professional people have been so naive and amateurish in allowing works to progress in such a haphazard fashion. If necessary it may mean undoing work that has already been done!

Final point - the SE should double check their calculations - the steel rods will not break, but they may stretch beyond design tolerances and cause other safety critical problems.

Regards
 
I would suggest that you get hold of some degreasing agent and try and undo what you have done!

It's a bit late.
The pour has taken place and stripped today.
Applying the mould oil without spraying the re bar was impossible on this first section. Degreasing the rebar deeply embedded inside the shutter would also have been impossible, at least not without degreasing the shutter and then your back to square one.
Subsequent pours will hopefully be faster as a large shuttering section is now assembeled and the oil will be applied beforehand.
Given the amount of reinforcing though in this structure Im confident the roofing engineers threaded bar ( passed by the SE) will snap before the re bar fails inside the concrete.
In any case it says this in the link above....

The Aberdeen Group tests were
made with 100% contaminant coverage
of the reinforcing steel, they
represent the worst possible case.
Under these severe conditions, the
contaminants didn’t adversely affect
bond.

A little respect wrote
the steel rods will not break, but they may stretch beyond design tolerances and cause other safety critical problems.

May I ask what qualifications you have to make such a statement?

If the steel rods try to stretch at all they will very quickly break and the entire structure may go like a zip. That's my opinion anyway.
 
Norcon, the use of unrated steel sounds very dodgy to me. Especially in critical locations.

Assuming you are a main contractor or subbie I would be inclined to clarify the instruction in writing. That should really be done through your contractual employer - which depends if you are main or sub? Either way it won't be the SE.
 
The SE has contacted the main contractor today telling him the threaded bars he OK'd last week are not up to the job and that he cannot sign them off.
It's taken him a week to realise this unfortuanetly. He has accepted full responsibility.

Two huge columns are concreted and he now tell us the (chinese re-cycled coke tins lol??) threaded bar will be removed using breakers and the correct bolts set in place and re-concreted in.
Probably cost about £2k to rectify and will mess up the aesthetics of the columns.

Pouring tomorrow again with the correct anchor bolts. We took two days off the shuttering assembly this time.
So were speeding up. :D :D
 
Whey - hey!!
Result!!

Well done diynotters - give yourselves a pat on the back. Major life-threatening tragedy avoided!
 
Hi

Not wishing to cause any offence, but £2k sounds a ridiculously low amount of money to cover the reinstatement works.

I assume that in order to guarantee the integrity of the structure that the whole of the affected structure would have to be taken back to 'ground zero' and be rebuilt, rather than simply replacing a section of one or two columns?

As an aside I would like to mention that insofar as this discussion forum is concerned I am only making impartial comments and not providing unsolicited advice in any shape, manner, or form on what should or should not be done, and for these reasons the reader should place no reliance or relevance upon the comments that I make.

Regards
 

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