1 cement 4 sharp sand to reinforce support for RSJ?
Dec 05, 2017 9 Replies
G
George Miles
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
formatting link
george
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N
newshound
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.
G
George Miles
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
T
The Natural Philosopher
strongest is 2:1 sand:cement.
also pretty impervious to water
T
Tim Watts
I learnt 1:3 was the strongest.
G
George Miles
T
Tim+
What does it hold up? How long has it been there? Does it need anything doing?
Tim
D
Dave Plowman (News)
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.
A
Andrew
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.
G
George Miles
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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