Need to put up a small concrete wall - 600mm*500mm*40mm

[alpsy]

Hi guys,

We have built this small pond and now i want to design a filter for it.

To do so, i need to put in one wall (see pic ... wall needs to go from top to bottom of pic basically seperating pond from filter).

Thinking best option is put up a little formwork put 2 pieces of vertical and horizontal rio and run my pvc pipes through sections before pouring 40mm or so thick concrete.

Will this work ... pond will hold about 1400lts and want to be sure that wall can withstand the pressure? how thick do i need to bury the concrete into the existing concrete?

Thanks,

Julie

[MrFixIt]

Hi guys,
Thinking best option is put up a little formwork put 2 pieces of vertical and horizontal rio and run my pvc pipes through sections before pouring 40mm or so thick concrete.

Will this work ... pond will hold about 1400lts and want to be sure that wall can withstand the pressure?

Yes that will work. There will not be a lot of pressure to be too concerned with as the water is not that deep.


how thick do i need to bury the concrete into the existing concrete?

Julie

You don't need to bury the new concrete into the existing concrete.

For stability and structural strength it would be a good idea to drill a few 6mm holes (4-5 holes) in the base and walls of the existing concrete, into which you will place short lengths of reo. These short bars could be tied to the reo you are going to place in the wall but it is not absolutely necessary to tie them together.

I would also suggest you use some very small aggregate (stones) in the concrete mix this will help prevent cracking and make the wall stronger (not that the wall really needs to be that strong).

When you "pour" the concrete wall, as it is quite "thin" (40mm) you will need to "agitate" the concrete by poking it with something like a piece of 6mm rod (used to tie the wall to the existing concrete). You should do this while pouring the concrete to ensure a good flow around the reo and up against the formwork.

Don't let the concrete dry out too fast as it will be liable to crack (not a good feature :) ). Keep the concrete wet or at least very damp After removing the formwork) until it cures. I would suggest at least 48 hours, but maybe someone with more concrete knowledge can suggest more info.

When the wall is ready you will then need to apply a waterproof membrane to the pool side of the wall to prevent leaks (around the pipes and wall edges) between sections.

HTH

[alpsy]

thanks hth,

shame i cant just use to a thin large paver for the wall ... scared it wont be strong enough and wont have a firm hold w/o the rio.

so how deep does the rio have to go into the existing concrete?

will try and tackle this project in coming weeks

cheers,

julie

[addo]

Am I misreading the schematic, or will the partiton have water on both sides, to similar height?

Also, with thin concrete if you want to reinforce maybe stainless is the go. Hand-placed concrete (unless it's a strong mix and you vibrate it) may well be porous enough that a 20mm cover to the reo (centred in a total partition thickness around 40mm) will be inadequate to prevent permanent wetness of the metal.

To "pin" or engage the new concrete against existing, you could even use a couple of all stainless Dyna-Bolts or stainless coach screws in Ramplugs.

Regards, Adam.

[alpsy]

Am I misreading the schematic, or will the partiton have water on both sides, to similar height?

Thats correct.

How about instead of concrete (given small thickness, I use 40mm aluminium extrusions which i dynabolt into the concrete, silastic edges and then glue tiles on walls to work as dividers?

Would this be a better solution?

Cheers,

Julie

[addo]

The reason I'd asked about water either side of the wall, was to check there's no real hydrostatic load on it - there isn't, so that makes life easier.

Not sure about the durability of aluminium in constant water exposure. I would take the assumption that any outdoor waterproofing system is bound to leak or fail slightly, so what are the consequences? (In this case, it could be oxidisation that "blew" the tiles.)

If the wall were designed thicker, a piece of 75mm Hebel might work, provided you used a tanking membrane that allowed over-tiling. If you could find a similar styled product for commercial cladding that were thinner, this could be the easiest bet.

Whichever way it ends up going, using bond breakers in the corners (as per waterproofing standard AS 3470) before the final tanking process, would be good practice.

Regards, Adam.

[MrFixIt]

thanks hth,

shame i cant just use to a thin large paver for the wall


You could, but then you may have problems making it fit and or getting the pipes through.


... scared it wont be strong enough and wont have a firm hold w/o the rio.

It would be strong enough, it just might be a little awkward attaching the paver to the existing concrete. It could be done with some stainless angle and stainless screws etc.


so how deep does the rio have to go into the existing concrete?


Maybe 20mm. It is only there to keep the "new" concrete panel in place. It will not be supporting any "real load".

If there is no problem with water seeping berween the sections and there is water either side of the panel then almost anything that is waterproof, ie even 10mm perspex could be used as the separating panel. If the water is the same level either side of the panel then there is effectively no load on the panel.

If you need to prevent seepage then a waterproof membrane or waterproof silicon adhesive (or smilar) coul be used to seal around the perspex etc.

By the way the HTH at the end of my message stands for Hope This Helps :)