h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Entry: Ordering Concrete - Layman's Guide for Patio Construction - A884388
Author: Dr Montague Trout - U188966

Here we go. Completely innocent from beginning to end.

For record, I got it from Flea Market

A760079 Ordering Concrete
F91197?thread=186945 Old Peer Review Thread

I hope I've credited everyone correctly.

So what kind of cheese is this ?

Good solid stuff. Exactly what the guide needs.

Sprout

I don't think I'm going to entice "The Angry Young Men" to participate in robust debate with this am I?

Damn it, Trout!

THere's nothing wrong with this! Nothing to complain about

Same here, can't complain. Although is it really Nmm^2 or should there just be one m?

Tango

Indeed mm. But should be N/mm2.

1 Newton per square millimetre = 1 Megapascal

ah, milimeters, not meters. Pressure is normally messured in Newtons per meter squared, though, i thought. Is it just in the building trade that's its in mm, or am i remembering those boring physics lessons wrong?

Tango

I believe that "Newtons per square millimetre" is the correct SI Unit in this case, and even if it is not, it is most certainly the unit most frequently used alongside "MPa". Indeed, British Standard favours "N/mm2" over "MPa".

I might have been confused by Newton-meters, the mesure of moments (levers, etc.). I'll trust that you're right.

Tango

Maybe, maybe not.

Whilst an Engineer might use N/mm2 for concrete strength, I think he/she would most likely use kN/m2 for the pressure a structure exerts on the earth under the foundations.

Perhaps, it is a matter of choosing the appropriate units for the scale of the problem. For example, concrete's characteristic strength is probably used to some extent to calculate the ability of a beam, slab or column to resist failure under load. The cross-sectional area of steel reinforcing bars (and concrete members for that matter) are usually too small to calculalte in terms of m2, so mm2 is more appropriate. In which case, N rather than kN is the preferred unit of load.

Maybe.

DMT

Well done,, I'll try and be controversial so we can have a nice debate by asking what kind of canoe is made out of concrete!

Ah, that will be a concrete canoe.

yes the sort that can be found at the bottom of many a fine canal

http://www.seas.ucla.edu/asce/2003/Activities/Canoe.html

Don't really know what to say except I like the entry
I'm no expert on Physics/building/anything really, so for me to point out holes wouldn't be right...
Oberon2001

Anyone building a driveway this weekend?

I dunno, what with Alan Shearer creosoting his fence and you and your bloody patios...


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