1 cement 4 sharp sand to reinforce support for RSJ?

Dec 05, 2017 9 Replies

Today I found a steel RSJ sitting on only one brick. Luckily this time it seems to be an engineering brick with portland cement. I want to reinforce it, is



1 cement 4 sharp sand a good mix? With a temporary board in front so it doesnt fall out.

photo at

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george


Photo is not very clear, it looks to me more as though there are three bits of paving slab between the RSJ and the outermost brick. Is that a half brick, or is it a 9 inch wall?

I agree, the RSJ could perhaps be coupled a bit better to the "inner" brick. I'd say quite a lot depends on how much structure the RSJ is supporting, i.e. what's the likely load going down through the supporting wall? I'm not a structural engineer (well not for buildings, anyway) but someone here will know the codes.

That aside, your ratio sounds OK to me. Maybe even 1:3? But maybe builders sand? Not too much water.

I thought builders sand was softer and not to be used here, but i'm not an expert.

It's a corner, the bricks seem quite hard and the mortar seems to be portland.

I dont want to jack it up and remove the stones, the floor underneath wouldnt take the weight!

I plan to just reinforce it with lots of cement/concrete of a hard mix.

Unlike another RSJ which is on the end of crumbly brick with lime cement!

george

strongest is 2:1 sand:cement.

also pretty impervious to water

I learnt 1:3 was the strongest.

What does it hold up? How long has it been there? Does it need anything doing?

Tim

For strength, yes. Although I'm not sure what you intend doing. The normal way to support an RSJ in a 9" brick wall is to remove about 6 bricks of the inner layer, shutter up, and cast a padstone in situ from concrete. But a structural engineer is best used to calculate the actual load hence size of padstone needed.

It looks like a rotten timber lintel has been removed and replaced by (a not very well protected) steel. hence the gap above, below and around the end.

Is this a house or outbuilding ?. If the latter, with humidity levels likely to be higher, and without the benefit of heating then I would hack off all the plaster around that steel and give it couple of coats of anti-rust paint before doing anything structural.

I think a double brick wall was removed to knock two rooms into one. Its ho lding up an upstairs room full of tools and above that a lot of roof.

Someone on facebook suggested: "Get as much crap out from all around the end and dry pack it with 2 sharp sand to 1 cement. Put just enough water to dampen the mix ... little as pos sible to prevent shrinkage ram it right in bit by bit. That?ll sort it."

Which seems a good idea. I dont want to remove what's already there, but re inforce it with some mix of concrete....

There is another RSJ in the kitchen in a far worse state which I may jack u p and rebuild.

[george]

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