Garage base slab & expansion joints. - 5.6m x 5.4m base

[crawfy58]

Hi,

I am preparing the base for a concrete sectional garage.

It is 5.6 m by 5.4 m.
100mm concrete on type 1 sub base with DPM and A142 mesh.
Concrete will be 300mm at edges.

I have looked at the pages on this website and understand that i probably need some sort of expansion or crack control joint.

At the moment I have the formwork in place around the edges and some type 1 in place.

Can anyone advise what sort of joint I need if at all.

Cheers,

Iain

[lutonlagerlout]

well crawfy i would say if you use a pavemix concrete (one with fibres and high strength,and flexel all round the perimeter there would be no need for a joint in the slab
its only about a 4.5m3 pour,so if it has expansion all round and the steel and the fibres it should be ok
only an engineer could say 100%
cheers LLL

[crawfy58]

Thanks LLL.

Not having done this amount of concreting before but being reasonably handy do you think this amount can be handled and tamped by a relative concrete novice?

I am looking at using a readymix service with a chute as its only about 10 feet from access road.

Cheers,

Iain

[TrevorL]

I recently put down a 5.52m x 4.84m x 150mm slab in two sections with just my son-in-law to help me, and at the time I thought we had made the right decision splitting it into two.
I would say that if you do it in one hit you will need about another 3 helpers.

[crawfy58]

Thanks for your advice.

If I do it in two sections do I just leave DPM in place and put timber formwork across middle ?

What do I do with steel mesh - I presume this is now split into two seperate sections as well ?

Also when the first side has hardened do I remove timber and pour directly against concrete or use some sort of joint ?

Sorry for all the questions - trying to do the best job I can.

Cheers,

Iain

[IanMelb]

There's a whole section in the main website about jointing concrete pads

[very simple simon]

You can leave the polythene in one big sheet, but watch you don't tear it barrowing and walking on it. Probly better to cut it off 12" after shutter and lap and tape in new section once first bay has gone off and shutter is struck.

Mesh, yes in 2 sections. Very advisable to dowel between joints, bitufibre required as minimum I would reckon

see the website as well. Might be worthwhile to think about some extra bars in the edge thickning, but its only a garage so don't think too hard.

[crawfy58]

Cheers for the suggestions -

I think I will go for it in 2 sections.

Will cut DPM and rejoin after 1st section done.

Also will use Dowel bars and some form of jointing board.

Cheers ,

Iain

[TrevorL]

Iain
Here are some pictures from when I laid my slab. They might help you. I didn't use dowel bars.
Cheers
Trevor

[crawfy58]

Cheers,

Looks like a neat job.

Did you use any sort of joint between your two sections?

Iain

[TrevorL]

Yes, I did, I used 12mm Filcrete, as I did around the edge. It also enables the shuttering to be removed without a release agent.
I filled the gap with Polysulphide sealant about a month after the slab was laid.
Cheers
Trevor