I'm now ready to pour my floor slab. 5 inch thick slab over 3 inch
kingspan.
I'm getting readymix pumped to the site. What mix should I ask for
(C20, ST4 etc) ?
Also, will I need reinforcment in this (fibres, steel mesh
reinforcement) ?
Thanks,
Simon.

sm_jamieson  wrote:

>I'm now ready to pour my floor slab. 5 inch thick slab over 3 inch
>kingspan.
>I'm getting readymix pumped to the site. What mix should I ask for
>(C20, ST4 etc) ?
>Also, will I need reinforcment in this (fibres, steel mesh
>reinforcement) ?


If you don't tell us what you intend to put (or build) on this slab,
how can anyone possibly tell you what you need?

Bruce wrote:
> sm_jamieson  wrote:
>
>> I'm now ready to pour my floor slab. 5 inch thick slab over 3 inch
>> kingspan.
>> I'm getting readymix pumped to the site. What mix should I ask for
>> (C20, ST4 etc) ?
>> Also, will I need reinforcment in this (fibres, steel mesh
>> reinforcement) ?
>
>
> If you don't tell us what you intend to put (or build) on this slab,
> how can anyone possibly tell you what you need?

It's a floor, hence the subject title of 'floor slab', coupled with the 
opening line: 'I'm now ready to pour my floor slab.'

HTH

1) If he was building on it, it would require footings, even for an internal 
wall, ergo it wouldn't be a floor slab.
2) What kind of things do people normally put in extensions?

My guess is either a bathroom or a kitchen, possibly a bedroom, so the 
heaviest thing it's likely to hold up is a washing machine.

To the OP, no you don't need reinforcement, nor fibrin.
When you ring to ask for premixed, they will ask you what it's for and 
deliver the correct mix, or if you decide to mix it yourself, a standard 
6:3:1 mix is more than strong enough

On 20 Aug, 16:59, Bruce  wrote:
> sm_jamieson  wrote:
> >I'm now ready to pour my floor slab. 5 inch thick slab over 3 inch
> >kingspan.
> >I'm getting readymix pumped to the site. What mix should I ask for
> >(C20, ST4 etc) ?
> >Also, will I need reinforcment in this (fibres, steel mesh
> >reinforcement) ?
>
> If you don't tell us what you intend to put (or build) on this slab,
> how can anyone possibly tell you what you need?

Oh sorry, its easy to forget not everyone else knows what you are up
to !!
Its the floor slab of the extension I am building. Slab on top of 75mm
kingspan,
with 25mm kingspan up the sides.
Thanks,
Simon.

On 20 Aug, 17:40, Bruce  wrote:
> sm_jamieson  wrote:
> >On 20 Aug, 16:59, Bruce  wrote:
> >> sm_jamieson  wrote:
> >> >I'm now ready to pour my floor slab. 5 inch thick slab over 3 inch
> >> >kingspan.
> >> >I'm getting readymix pumped to the site. What mix should I ask for
> >> >(C20, ST4 etc) ?
> >> >Also, will I need reinforcment in this (fibres, steel mesh
> >> >reinforcement) ?
>
> >> If you don't tell us what you intend to put (or build) on this slab,
> >> how can anyone possibly tell you what you need?
>
> >Oh sorry, its easy to forget not everyone else knows what you are up
> >to !!
> >Its the floor slab of the extension I am building. Slab on top of 75mm
> >kingspan,
> >with 25mm kingspan up the sides.
>
> No need for mesh reinforcement as it isn't loadbearing.  Addingfibres
> might help to distribute future shrinkage of the slab into a myriad of
> tiny harmless cracks rather than a small number of wider ones, but
> they are not essential.
>
> If you tell the readymix company what theconcreteis for, they will
> recommend a mix, or a choice of mixes.  They will also offer
> admixtures that help make compacting and finishing easier.

Thanks. Its to have a screed over later (when levelling up to rest of
the house), so a fine finish is not required.
I assume stamping around in it a bit and tamping as usual with a long
bit of wood will be enough to compact it ?
Someone will suggest a vibrating poker I'm sure but thats got to be
overkill for a slab.
Simon.

sm_jamieson  wrote:
>On 20 Aug, 17:40, Bruce  wrote:
>> sm_jamieson  wrote:
>>
>> >Oh sorry, its easy to forget not everyone else knows what you are up
>> >to !!
>> >Its the floor slab of the extension I am building. Slab on top of 75mm
>> >kingspan,
>> >with 25mm kingspan up the sides.
>>
>> No need for mesh reinforcement as it isn't loadbearing.  Addingfibres
>> might help to distribute future shrinkage of the slab into a myriad of
>> tiny harmless cracks rather than a small number of wider ones, but
>> they are not essential.
>>
>> If you tell the readymix company what theconcreteis for, they will
>> recommend a mix, or a choice of mixes.  They will also offer
>> admixtures that help make compacting and finishing easier.
>
>Thanks. Its to have a screed over later (when levelling up to rest of
>the house), so a fine finish is not required.
>I assume stamping around in it a bit and tamping as usual with a long
>bit of wood will be enough to compact it ?
>Someone will suggest a vibrating poker I'm sure but thats got to be
>overkill for a slab.


If you ask the readymix supplier to tell you what admixtures are
available, one will be a super-plasticiser that makes the mix
effectively self-compacting.  You just need to screed it off to the
finished level.