Footing advice and core fill advice for 600mm retaining wall

Jennever · Feb 18, 2024 7:04 am

I'm DIY 2x 600mm by 17 metre retaining walls as leveling sloped back yard to split level. Using interlocking Versa-lock abri masonry blocks.

After advice about concreting process for footing and core filling.

Trench 400mm wide x 200m deep - concrete with Rio bars ever 400mm. Then once set mortaring first block level on then stacking with Rio bars in 2 blo
ck horizontally along wall. Then core filled with concrete 20mm aggravate.

My main question will I be okay doing this above plan with concrete mixer? I will have my dad with me so one mixing and one pouring as don't want the trench setting in sections. Just trying to save on pump and concrete truck cost since it's not that big of a wall.

I have seen that 600mm retaining walls and under don't need concrete footing and fill just compact road base and core fill aggravate. The concrete plan is more for longevity and since I'm gap filling cracks and painting it with render paint I think with out concrete infrastructure would move a lot more. Or this just over kill?

Pulse · Feb 18, 2024 8:24 pm

Versaloc is a mortarless besser block system that still needs a properly engineered footing. If you just do a 400x200 footing it will fail in time. At 17m long you need it stable or it will crack and look horrible. The walls without footings i think are flexible gravity dry stacked walls, built with a slope, designed to move a bit if needed.

I’m a DIYer and don’t mind mixing stupid amounts by hand but I would consider a few options. I would either use dincel or cast it insitu with formwork.

Both need a decent footing about 500w x 300d minimum. Aim for 200mm wide wall. You could probably pour a 300w wall and just hope keeps it there. You could use a 2400 length of formwork and pour in sections hand mixed, reusing form as you go. If you use dincel then seriously get a pump and save a week of hard work. 17m x 2 is a massive project. Mixing that much is exhausting.

If it was me, I’d suspend the dincel above the footing in midair, get a pump, pour the footing, wait an hour, get the next load and fill the dincel. The footing will be cured enough to resist the 600mm pressure head of the wall above. All done one day, pay for pump once only, use all 4 hours you pay for.