how thick for readymix?

GERMAN ROCKS

Have a shed that I have turned into a workshop. Need to put concrete down inside. How thick would it need to be? Would 5 inches be enough? Heaviest machine entering would be the backhoe (weighing about 10 tonne at most). Also 35n or 30n?

Jack the Stripper

6 inches minimum with steel reinforcing. Let's keep the cowboys riding horses.

Genghis Cant

We put in a good bit of concrete over the years and one thing I came to understand was that in most jobs the difference between doing a top of the range job and a middling job is often very little.

pedigree 6

5 inches is nothing.
As said here 6 inches minimum and then with some reinforcing.
Any concrete I get now is 35 or 40N.
For a workshop, no harm getting in a powerfloat as well.

Do it once. Do it right.

foxy farmer

pedigree 6 wrote: »

5 inches is nothing.
As said here 6 inches minimum and then with some reinforcing.
Any concrete I get now is 35 or 40N.
For a workshop, no harm getting in a powerfloat as well.

Do it once. Do it right.

My structural engineer recommends 8 inches of 50N just to be on the safe side

Jack the Stripper

It had to happen.

foxy farmer

Of course it did. As sure as night follows day.

Nekarsulm

https://m.youtube.com/#/watch?v=4x23l6BGu3w

mythos110

More important to have the base right first. Get some good quality fill (actual clause 804 not whats normally sold as 804) and a vibrating roller. With the base right, you'd hardly need the concrete but as others have said, may as well but 6 inches as 4 when doing a job like that which will last a lifetime.

3 the square

If some one was replacing a yard outside a milking parlour where the milk lorry pulls to collect the milk what depth of concrete and what strength of concrete should be used??

Sam Kade

foxy farmer wrote: »

My structural engineer recommends 8 inches of 50N just to be on the safe side

It's a wonder he doesn't recommend a foot, 6" of 40N with reinforcing is strong enough unless you're building a rocket launching pad.

Sam Kade

3 the square wrote: »

If some one was replacing a yard outside a milking parlour where the milk lorry pulls to collect the milk what depth of concrete and what strength of concrete should be used??

6" 40N with reinforcing.

Bass Reeves

If put down right as another poster said and base properly compacted in layers or if old floor that is well compacted I would see no real need for concrete some lads are talking about.. It is unlikely you will be putting a truck with 25 ton in it or a low loaded with a track machine on it. If you are putting mesh in it a strong four inches is plenty. If you are getting concrete from a good supplier 30 N is adequate as well I noticed a few time lately with small loads I ordered 30 N and got 35N as that was what was set for the jobs that were on.

A back hoe is hardly 10 ton, but even a 10 Ton machine will be at most 6 ton/ axle. A backhoe is less than 4 ton/ axle. If I wanted to spend extra money I would go for fibres so floor would never wear and I am not sure I would do that if I was capable of putting it in without extra water.

pedigree 6

Farmers who don't put down the right depth and proper strength of concrete.

pedigree 6

Sam Kade wrote: »

6" 40N with reinforcing.

They're putting in 6 to 7 even 8in around here with reinforcing for the artic lorries around here now.
How many yards do you see being broken up with the big artic lorries now.
Those little rigids are long gone.

As I say do it properly and futureproof it.
Concrete's only dear the day you put it down worse if you do a half assed job and have to tear it up and do it again.

Jack the Stripper

Is it any wonder that all the housing estates built in the boom times are falling apart when people are arguing over an extra inch or two of concrete.

3 the square

any one know how u calculate how many meters of concreate u need for a job ??
just wondering how much a job would cost.

pedigree 6

3 the square wrote: »

any one know how u calculate how many meters of concreate u need for a job ??
just wondering how much a job would cost.

Measure in metric for a start.

(I'm just using these measurements for an example).
So say 6in roughly 0.15m is the depth.
Say 10ft roughly 3.05m is the width.
Say 12ft roughly 3.66m is the length.

So 3.66m x 3.05m x 0.15m = 1.67cubic metres of concrete.

So Length x Width x Depth = amount of m3 of concrete.

foxy farmer

pedigree 6 wrote: »

Measure in metric for a start.

(I'm just using these measurements for an example).
So say 6in roughly 0.15m is the depth.
Say 10ft roughly 3.05m is the width.
Say 12ft roughly 3.66m is the length.

So 3.66m x 3.05m x 0.15m = 1.67cubic metres of concrete.

So Length x Width x Depth = amount of m3 of concrete.

If you're doing a job with your own mixer a cu m will need about 2.25 tonnes of gravel. 20t load should do close to 9 cu m.

Sam Kade

pedigree 6 wrote: »

Measure in metric for a start.

(I'm just using these measurements for an example).
So say 6in roughly 0.15m is the depth.
Say 10ft roughly 3.05m is the width.
Say 12ft roughly 3.66m is the length.

So 3.66m x 3.05m x 0.15m = 1.67cubic metres of concrete.

So Length x Width x Depth = amount of m3 of concrete.

Or you could do it the lazy way using google, http://www.calculator.net/concrete-calculator.html

I was getting readymix last year for a wall but there was a slope of 1.5 feet from one end to the other, the builder got bogged down with his calculations because of the slope. I calculated it at 9.5 m2 the readymix crowd said 10 m2 so the builder decided on 9.75, when the shutters were filled we had .25m2 left over.

foxy farmer

Let's not forget the consistency of the ready mix. If you like spreading "soup " ie plenty added water, your cured concrete won't have the strength of the original specified mix. Laying a damp proof course will hold the moisture and slow the setting process

Nekarsulm

foxy farmer wrote: »

. Laying a damp proof course will hold the moisture and slow the setting process

Gets rid of those holey old silage covers as well!

foxy farmer

Sam Kade wrote: »

Or you could do it the lazy way using google, http://www.calculator.net/concrete-calculator.html

I was getting readymix last year for a wall but there was a slope of 1.5 feet from one end to the other, the builder got bogged down with his calculations because of the slope. I calculated it at 9.5 m2 the readymix crowd said 10 m2 so the builder decided on 9.75, when the shutters were filled we had .25m2 left over.

Can't go too far wrong with quantities for a shuttered wall. Would never take quantities supplied by ready mix suppliers to be gospel. Neighbour had issue regarding shortage in a load supplied for shed wall a few yrs back. They came out measured the wall checked the docket questioned driver scratched their heads and came up with some BS about batching plant working by weight and wet ingredients weighing more for specific volume. The consignment was 0.75 cum short in a 6cu m order.

foxy farmer

3 the square wrote: »

any one know how u calculate how many meters of concreate u need for a job ??
just wondering how much a job would cost.

If you watch to be really awkward measure in feet, get your cubic ft total and either divide by 35.32

Or multiply by 0.028 to get the cubic m equivalent

patsy_mccabe

Sam Kade

foxy farmer wrote: »

Can't go too far wrong with quantities for a shuttered wall. Would never take quantities supplied by ready mix suppliers to be gospel. Neighbour had issue regarding shortage in a load supplied for shed wall a few yrs back. They came out measured the wall checked the docket questioned driver scratched their heads and came up with some BS about batching plant working by weight and wet ingredients weighing more for specific volume. The consignment was 0.75 cum short in a 6cu m order.

But this wall was on top of another wall that had a 1.5 foot fall both sides, you add the depth at both ends and divide by 2 to get the average depth, the builder didn't have a clue how to measure it.

Who2

5" of concrete with fibre in it is more than adequate for nearly any shed floor. 35n with extra sand and you should have a decent job. if expansion joints are put in the proper places and the base is put in right youll have no issues. we have a yard here put in over twenty years now at just over 4" deep, theres regularly 34 ton crossing and turning on it and not so much as a crack. put in 6", 8" or 12" if you want as its you who'll be paying for it. but i think its overkill unless there,s a piss poor job done on the base and then its still likely itll crack even with 8".

Bass Reeves

I think some lads would want to read the question it like the leaving certificate. I was always advised to read it twice and then again. OP says it a shed conversion. It is unlikely there will be 20 ton loads crossing it. As well he mentioned that the largest machine that will be on it is a back hoe. Now there is not much future proofing here. It is u likely he be knocking the shed, or have a road through it for HGV or Volvo dumpers unless he is going to take the f@@king roof off.

If I was giving any advice about future proofing I say put a pit into it but that is another matter. If you are really good with concrete you would get away with 3.5'' with steel and fibres. Get a road saw to cut the slab while it is still fresh ( after 24 hours ) you would nearly get away with a single blade for expansion channels. Put in your mesh and fibres. But personally I go with the four inches. The reason we had shoddy build during the boom had nothing to do with skimping with concrete. It was all to do with bad workmanship. Most buildings are structurally sound, it firesafety, cheap filling materials and shortcuts that were all the problem. It was the load of mortor that was dropped of on the one go at 7.30 am and lads adding washing up liquid to it to keep it pliable after lunch and even often at 6 or 7 pm was the issue.

Jack the Stripper

Good to have experts to share their advice.

pms7

What annoys me is guys thinking a track machine driving up and down will compact stone.
The grant spec for a silage slab is only 5'', but the important part is, "on a well compacted base"
My builder said concrete will always crack, when we were looking at an old slab, and he was extending it. I'm doing the current extension to it myself, and wont be using thin watered down concrete. He was looking at me when I was curing the slab with plastic on top. At concrete ten years and never cured a slab!

Sam Kade

pms7 wrote: »

What annoys me is guys thinking a track machine driving up and down will compact stone.
The grant spec for a silage slab is only 5'', but the important part is, "on a well compacted base"
My builder said concrete will always crack, when we were looking at an old slab, and he was extending it. I'm doing the current extension to it myself, and wont be using thin watered down concrete. He was looking at me when I was curing the slab with plastic on top. At concrete ten years and never cured a slab!

You may as well let us all into the secret, what compacts the base?

Jack the Stripper

A roller.

larthehar

We had a flat lane here.. redone every 3-4 yrs compacted with a track machine.. the last time i did it.. 5yrs ago, i hired a vibrating 2 ton roller.. IMO, it is the vibration that makes it..
Used a whacker plate for a floor in a new shed and questioned if i needed concrete at all when it was done!

Jack the Stripper

larthehar wrote: »

We had a flat lane here.. redone every 3-4 yrs compacted with a track machine.. the last time i did it.. 5yrs ago, i hired a vibrating 2 ton roller.. IMO, it is the vibration that makes it..
Used a whacker plate for a floor in a new shed and questioned if i needed concrete at all when it was done!

+1, cowboys seem to be driving diggers by that lad.

Water John

Whacker plate, great job on 804. Hire one for a half day.
4/6" of 35N concrete. Mesh 1.5" up from the base. Not in the middle of the concrete!!

O.A.P

Track machines can travel on bog.
@ Sam Kade
any builder that cant measure something so easy is at the wrong job.
How did you measure what was left over though ?

Jack the Stripper

Can't pour concrete on bog.

O.A.P

Jack the Stripper wrote: »

Can't pour concrete on bog.

Why?
A track machine wont compact stone ,804 3 inch down, or quarry run though.

Jack the Stripper

I never said it did, we need the expert foxy farmer for advice on this.

Reggie.

O.A.P wrote: »

Track machines can travel on bog.
@ Sam Kade
any builder that cant measure something so easy is at the wrong job.
How did you measure what was left over though ?

Tbf them track machines have large oversize tracks but still sink sometimes

patsy_mccabe

A track machine is designed to spread the weight as much as possible. Even a tractor would be better at compacting the base. It would have higher ground pressure. Use the proper machine, a wacker.

st1979

Friend of mine worked with builder for 15yrs was helping me lay concrete. He taught I was very lucky it was so sunny. He reckoned the concrete would dry out nice and fast and be better for it. He never knew concrete should be cured slowly for strenght

st1979

Vibrating rollers are actually great value to hire around 100 a day. If you got a decent amount to do.

3 the square

Ok chaps let's say a guy puts the concrete down at 8 inches tick
How long before the milk lorry drives over the new concrete if it's put down on summer months ??

Reggie.

3 the square wrote: »

Ok chaps let's say a guy puts the concrete down at 8 inches tick
How long before the milk lorry drives over the new concrete if it's put down on summer months ??

I was always taught that concrete takes 3 weeks to full cure

Bullocks

st1979 wrote: »

Friend of mine worked with builder for 15yrs was helping me lay concrete. He taught I was very lucky it was so sunny. He reckoned the concrete would dry out nice and fast and be better for it. He never knew concrete should be cured slowly for strenght

Ah now, he must've been pulling your leg! 15 yrs? What was he doing for the builder I wonder?

Water John

Concrete is curing over a year. The rule was for silage slabs to give them 28 days.
If its a handy size area, esp in a shed, a whacker is more manouverable and will do fine.

patsy_mccabe

3 the square wrote: »

Ok chaps let's say a guy puts the concrete down at 8 inches tick
How long before the milk lorry drives over the new concrete if it's put down on summer months ??

Wasn't 6 weeks to cure, the time recommended for back filling on the slatted tanks.
A lot of people out there think setting and curing are the same thing. "You could drive on that tomorrow" - heard that a lot.



http://www.cement.org/for-concrete-books-learning/concrete-technology/concrete-construction/curing-in-construction

foxy farmer

I've seen a 6" slab laid on a Saturday morning taking a twin axle artic tanker driving over it the following Monday afternoon. Far from ideal but couldn't be avoided. Sub base was dug out of ground carrying heavy traffic for years. Could you do it in sections and keep the lorry off the fresh section?

Bass Reeves

Water John wrote: »

Concrete is curing over a year. The rule was for silage slabs to give them 28 days.
If its a handy size area, esp in a shed, a whacker is more manouverable and will do fine.

Concrete keeps curing for years and years. The dome of the Pantheon in Rome is made of concrete with no steel in it. It is considered to be strong now than when it was orginally build. Concrete reaches it 75% of it strength after 28 days curing. However it will continue to cure after that. Most specs for concrete are specified for 28 day stage. So in theory 35 N concrete is 35 N strong at 28 days. But it will cure as it hydrates and get stronger and stronger.

However you can spec Concrete for a shorter duration ie 35N at 7 days. This means that this mix will be 35N at 7 days but it will be over 40N at 28 days. 35N concrete will max out at over 45N over time.

patsy_mccabe

There was a guy on the Journal a while back that was grooving concrete. He was saying that the older yards, as in 30 years old were may harder to cut than the more recent ones.