You learn something new every day!

[XmisterIS]

And today it is all about cement/ballast ratios ...

I have just finished laying concrete for a patio (and it's damn near killed me! Never again - next time the builder is doing it!)

I often wondered what the correct ratio is; when you do a google search, you'll find all sorts of different answers!

Well, I've just learned about the "M" rating - it seems we've mixed M15, or thereabouts, for the bit that we thought was wrong, and M20 or M25 for the rest. So it's not wrong at all, and even M5 would do for a patio!

the numer after the M is newtons per square mm of compressive force after 28 days, apparently. I was very surprised by how little cement there is in M5 and M10 mixes!

 

[Dayvo]

When I was a hod carrier, we used a 7-2, or 8-2, mix of sand to cement.

 

[XmisterIS]

yeah, we were going for 8-2, but started off 8-1.5. Seems there's nothing wrong with that so long as it doesn't get too wet! (which our's didn't). My builder mate who I phoned up in a slight panic said, "Nah mate, don't worry about it!".

 

[Dayvo]

I take it you used a mixer!

I HOPE you used a mixer!

 

[XmisterIS]

I take it you used a mixer!

I HOPE you used a mixer!

I would be in hospital if we didn't .... one and three quarter tonnes!!!!!!

 

[Archie_tect]

XM, exactly what is it that you're intending to build on top of your patio?

 

[asterix]

Depends what it is for?

When I laid the floor in my barn it was all readymix in a big lorry. Spreading it was bad enough. They seem to have got the mix right! I did a small area later and it needed 15 mixer loads. Hard work indeed!

If you have any sort of volume you need readymix. And chances are you'll have some over unless you don't order enough. Too much is better IMO.

 

[Archie_tect]

.... you'll have some over unless you don't order enough.

A+

 

[XmisterIS]

XM, exactly what is it that you're intending to build on top of your patio?

A lauch pad for the starship enterprise!

Seriously, I will only be me, XmrsIS, a table, a parasol and a dainty cocktail or two ...

 

[Dayvo]

A+

 

[XmisterIS]

Depends what it is for?

When I laid the floor in my barn it was all readymix in a big lorry. Spreading it was bad enough. They seem to have got the mix right! I did a small area later and it needed 15 mixer loads. Hard work indeed!

If you have any sort of volume you need readymix. And chances are you'll have some over unless you don't order enough. Too much is better IMO.

That is a lot!! We just did it in a mixer, it took all day though. It was about two tonne bags of ballast. I'm never doing that volume with a mixer again though!

It makes me wonder, before the days of mixers and readymix, do you suppose that on big jobs they had an army of apprentices just mixing concrete by hand?

 

[asterix]

Yeah well some people think they'll get it it right. My friend was a bit mean with ordering had a huge deficit and went into panic mode, sent the wife down to the builders merchant to buy more ballast whilst he feverishly mixed more concrete. Even then they didn't get the floor level and had to do a bodge job.

I was left with enough to build foundations for a 5 metre length of wall for which I had already dug the trench having been given timely advice.

Anyway it's not what's on the patio that matters, it's what's under it..

 

[vernon]

XM, exactly what is it that you're intending to build on top of your patio?

It's not so much what he's putting on top that concerns me but what he has put underneath.

Beaten to the post.

 

[vernon]

It makes me wonder, before the days of mixers and readymix, do you suppose that on big jobs they had an army of apprentices just mixing concrete by hand?

I spent a day mixing concrete by hand for a tight fisted git. Never again!

 

[Globalti]

Two tons? Pah! About 15 years ago I helped my pal mix EIGHTEEN tons of concrete for the footings for his new house. We used two mixers and two wheelbarrows and for a full day we mixed and belted back and forth dumping each load into the trench while his wife levelled and tamped.

Just a ton would probably kill me now though, once the old testosterone levels have dropped all that muscle just fades away and goes flabby.