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Risk of dislodged wall blocks during slab pour?


epsilonGreedy

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I am considering pouring my ground-bearing garage floor slab before the inner block wall rises above dpc, the motivation for this build order is to create a solid standing area as winter conditions turn 50% of my site into soft mud.

 

Is there a risk that the weight of the concrete during the pour will push up against the boundary blocks and dislodge them? I will give the blockwork mortar a week to reach maximum strength.

 

The technical details of the floor slab are not yet determined but a little reading around the subject leads me to think 150mm thick plus some rebar is in order.

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Is it a block on edge or onthe flat?

 

My initial reaction would be to pour, as the pressure at the edges isn’t that great.

 

If if you were concerned, You could prop the blocks temporarily, either by backfilling against them with site won material, or by using timber.

 

 

Edited by Triassic
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Wacking the sub-base in 50mm layers will almost certainly place more side load on the blocks around the edge than pouring, vibrating, levelling and floating the concrete I reckon.  I was surprised how much side load there was when just wacking two layers of MOT 1 for a path; I'd driven in stakes and fitted boards to contain the sub-base, but found they tended to push outwards a bit.

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You could infill with 100mm EPS and insulate below slab and it will also make the whole structure a bit more rigid for you. Also may help with your cavity sizing if you are DIY on the brick and block. Slope the top of it or just use 600mm DPC to make a step cavity tray as belt and braces. EPS doesn’t absorb water and is cheap too 

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