Concrete barrowing rates..

[The Natural Philosopher]

Hmm 20 tonnes odd.. certainly possible in dry form..but probably beyond most readymix lorries.

[The Natural Philosopher]

I cant remember how much is in my founadtions but IIRC it involved 3-5 readymixed lorries pumping when they could, and with us physically raking and barrowing to the far ends. Never did get it level properly either. about 5 blokes and most of the day. Very hard work.

[dennis]

[dennis]

That's the trouble with cowboy builders.. they don't have a clue.. they could have had a retardant mixed in and then they could have had all day to level it.

[The Natural Philosopher]

Dennis, it TOOK all day to level it. we ran out of time and we ran out of energy.

It just meant an extra days work for the brickie who laid the foundations to true it up.

The overtime on 5 exhausted blokes would have been more expensive.

But I do accept the project manager was almost as big a wanker as you which is why I fired him and took over the project myself after about 9 months.

[Jules Richardson]

Build yourself an 8m long chute - couple of guys at the front loading, one stationed partway down keeping the flow going, couple at the other end unloading and laying it out...

(OK, I was initially kidding, but part of me's now wondering aout slope angles, materials costs etc. - and even if you could make it a 9m chute and have the truck pour direct ;-)

cheers

Jules

[Roger Chapman]

My ever useful Architects and Builders Diary for 1956 has a table for "Materials per cubic yd of concrete".

For 1:2:3 mix (or 1:4.25 all in Mix) the information is as follows:

Tons (c. yds) gals. Cement Sand Gravel All in Water

.271 (.249) .601 (.499) .794 (.748) 1.395 (1.033) 30.9

So the all in aggregate is 1.35 tons to the cubic yard which is a good bit more than 1 ton but still closer than 2 tons. Gravel on its own at

1.06 is almost spot on.

TNP is well off on the water as well. 30.9 gallons is little more (29lb) than a quarter of a ton although it has to be said that concrete with the minimum amount of water tends to be very stiff and not easily laid.

Unless you add excess water. And, according to the information above, you actually get a slight shrinkage.

[John Rumm]

I thought most readymix ones were 6m^3 full load...

Don't know what those big mix on site ones can do though.

[fred]

In article , tony sayer writes

truck. The truck looked more like a tanker than a tipper and used a sealed auger at the back to mix on demand.

There were 2 men with the truck and they barrowed the lot about 10m to where we were levelling out on a mixed bag of strip found and massed concrete. The massed concrete was mixed slightly weaker.

They used oversize barrows and made it look effortless but they did insist that a path was laid with scaffold boards (just single file) to keep the rolling resistance down. We struggled to keep up with them.

I can't say I remember the exact time they spent on site but I'm pretty sure it was less than an hour.

At the time (5 or 6 years ago?) I think it might have been 120quid a cube for site mix vs 90quid for readymix. If you can find an outfit doing that sort of deal then it might be a cost effective option.

These guys were good but bear in mind that one here has reported an absolute disaster from a site mix outfit doing a shed/garage base although I don't think it was done on a large scale sealed auger mixer.

[Rick Hughes]

That is about right ... if you are having Readymix ... you won't barrow it fast enough unless you have a lot of guys and barrows.

Options ... get minimix and have it in 2 loads Specify retarder in mix to give you time to shift it. Have it pumped ... Have it delivered on conveyor mixer if that would get it where you need it .... but total volume is then down as truck has to reduce load due to conveyor weight Get motorised barrow ... these take much more than standard barrow Use a dumper Get mixamate or whatever local name is ... guy mixes it on back of truck and you barrow it

[Andy Champ]

A cubic yard is only about 90cm on a side. So only about 3/4 of a cubic metre.

Andy

[Roger Chapman]

Close enough for a back of an envelope calculation ;-) but slightly more accurate would be to multiply yards^3 by 1.3 to get metres^3.

But I was following up the earlier remark repeated below, hence yards.

"Rule of thumb is a cubic yard of aggregrate is a ton. As is a cubic yard of water. (Not exactly, but close enough for the back of an envelope.)"

Incidentally it is the cubic metre rather than the yard that approximates to a ton, ton and tonne being very similar amounts. 2240 and 2205 in lbs.