"Locke" - C5 & C6 Concrete Specification?

[jhardy1]

I just watched the movie "Locke" with Tom Hardy - it's a brilliant "thriller" following a construction manager trying to organise a massive concrete pour over his phone while driving on a motorway. (Now - that's not a movie pitch that you hear every day!) Highly recommended - and not just for Civil Engineers. (Watch it with your "other half", so that they can learn just how exciting your day to day job can be!)

Anyway - at several points in the narrative, the importance of using C6 concrete rather than the inferior C5 comes up. ("What does it say on the whiteboard, Donal? C6, not C5!") These are not terms that mean anything to me as an Australian Civil / Structural Engineer. Are these common specifications for concrete in the UK? It's pretty obvious from the dialogue that C6 > C5, but it would have been just as clear to a non-engineer that 40 MPa > 32 MPa, for example.

It's hard for me to imagine that this was just an example of sloppy writing that you might see in a Bruce Willis action movie, given the accuracy of the other technicalities that come up (slumping the mix, checking the shuttering, organising the traffic management etc - all nail-biting stuff in this context!)

I've tried Googling it, but all I can find are references to the movie "Locke".

http://julianh72.blogspot.com

 

[Ingenuity]

I thought (possibly mistakenly) that UK concrete was specified as "CXX", as in "C60" where "C" is for cube strength (not the more common cylinder strength of North America and AU, etc), and "60" was the specified compressive strength in MPa.

I have not idea what C5 or C6 refers. I would like to know...and I shall try and catch the movie too. Thanks.

 

[cvg]

google found this, see tables 2 and 3:

http://www.scielo.org.za/scielo.php?script=sci_arttext&pid=S1021-20192013000300002

 

[jhardy1]

Thanks cvg - but that's an academic paper where thee simply identify their 8 test mixes as C1 to C8 - plenty of papers around where that is done (or something similar). "Locke" is about a major construction project, with concrete coming from a number of batching plants around the city, so it would be far more likely that the mix designs would be to BS or Euro code.

WARNING - SPOILERS AHEAD!!!

DONAL (Voice on the phone): But I just got off the phone with the plant in Stafford and they said they know it’s a C6 mix, but how far toward C5 can it go. In other words, if one truck has some C5, how badly would that be taken?
Ivan lets the silence express his disbelief...
DONAL: Ivan, are you still there?
IVAN LOCKE: Donal, what does it say on the whiteboard?
DONAL: It says C6.
IVAN LOCKE: What does it say on every piece of paperwork and every sign off sheet?
DONAL: It says C6.
IVAN LOCKE: It says C6. And you know why?
A pause.
IVAN LOCKE: Because, eventually, when my building is complete, it will be fifty five floors high. It will weigh two million two hundred and twenty three thousand metric tons. My building will alter the water table and squeeze granite. Now...
A pause....
IVAN LOCKE: ...If the concrete at the base of my building is not right, if it slips a half inch, cracks appear. If cracks appear they will grow and grow and the whole thing will collapse.
DONAL: Ivan, look....
IVAN LOCKE: You make one mistake, Donal. One, little f***ing mistake, and the world comes down around you. So...
Silence.
IVAN LOCKE: Tell Stafford...
A pause.
IVAN LOCKE: C6.
DONAL: C6 it is.
Ivan cuts the call.

http://julianh72.blogspot.com

 

[jhardy1]

PS: I also wondered about a 55-storey building that would weigh two million tonnes, but I put that bit of hyperbole down to Ivan Locke's stressed state of mind!

http://julianh72.blogspot.com

 

[cvg]

its just a fictional movie, of course they made things up.

https://en.wikipedia.org/wiki/Locke_(film)

so apparently 225 concrete trucks are to access the site which amounts to a paltry 2200 cubic yards for the foundation of did you say a 55 story building? I don't think so. I'm thinking there would be some piles involved and the foundation would be much larger. and Birmingham is founded on iron ore, coal and limestone, but not granite...