Where to place Abelflex expansion joint foam filler before pouring concrete?

[Aaron89]

Hey guys, I've got to pour this L section of concrete under my rear balcony which at the moment is filled with rocks/stones. Where and which sides should I place Abelflex expansion joint foam filler?

Cheers,

Aaron

[EricL]

Hello @Aaron89 

Welcome to the Bunnings Workshop community. It's sensational to have you join us, and thanks for sharing your question about where to place the Ableflex in your new slab.

I recommend placing the Abelflex expansion joint foam filler around the entire area of the pour except the side that faces the grass. When pouring a slab next to an existing brick wall or concrete slab, install Ableflex Joint Expansion Filler between the new and existing structures to allow for movement and prevent cracking.

If you need further assistance, please let us know.

Eric

[Jewelleryrescue]

Hi @Aaron89  

Follow @EricL suggestion of placing  the foam all around the new slab against the brick walls and existing slabs. I would liquid nails glue it to the walls and other cement slabs just to hold it in place before the concrete is poured.

Now this is a very important bit Use a  Rotary hammer drill   and 12mm tip drill bits  and  drill into the surrounding concrete foundations also through the foam expansion 100 to 150mm deep and insert 300mm lengths of cut up reinforced  rod 12mm Spaced every 500mm.  The existing  slabs and  the brick wall.

Hammer these pins into the drilled holes until they sound solid.  Sometimes people like to glue these in with Chemset epoxy I find this unnecessary for a few reasons I won't bore you with the details around shear forces.  These pins in any concrete work will tie the level of two different slabs together so if there ever is movement they must move together or not at all.

All your slabs will stay at the same level if any ground movement.

EG council foot paths are not pinned together or have properly installed expansion joints, and they are prone to bucking 

I think we all have seen dissimilar moved slab heights from time to time so let's avoid it with pins.

[Aaron89]

Thanks so much for your help @EricL  and thanks @Jewelleryrescue for the extra input on the pins will definitely add them in!

[Jewelleryrescue]

Hi @Aaron89 

Just a last tip on the Reo pins drill them in approximately halfway in the thickness of the slabs.

As these pins are sticking out all around the existing slabs and brick work they are great to wire the reo mesh sheets too as well.

So the final effect is you have a new slab poured with expansion foam all around that means the new slab is free floating and expanding and contracting happily  but  with the steel reo rod in place the slabs will stay at the same height NO slumping causing height differentials 

Dont forget your plastic sheeting on the ground it helps cement form a strong and smooth under slab and protects the slab from acidic ground attacks which can fatigue the cement over time.  It also helps control the curing time process (as Water content is held longer )  as you want the slab to cure slowly as it will be all the stronger but not brittle.

Fun  fact :  The strongest concrete cures underwater as long as it isnt diluted by the water.