Padstone cast in place concrete mix

[an203888]

I want to cast one of my padstones in place as I can't get the right size.

Searched a fair bit and a strong 3:1 mix seems the be what I need but some have mentioned using a smaller aggigrate like 10mm rather than the usual 20mm.

Does anyone have any opinions on this?

 

[tony1851]

What size padstone do you need?

 

[an203888]

The spec on drawing is an L shaped 360 x 360 x 210 x 150 deep. They do one off the shelf for silly money which is 100 wide but not 210 wide, plus that particular Padstone seems very pricy.

Architect said I can cast in situ so just trying to find out what I should be using. Most people seem to use a standard ballast from what I can find but just use a strong mix.

 

[tony1851]

Casting a padstone that shape will be tricky, and regardless of the mix, it will not be as strong as one off the shelf.
Have you considered forming one in two-courses of engineering brick in 1:3 mortar?

 

[an203888]

Why will it be tricky exactly? Not really any trickier than a square one. Just shutter up at right height, pour, vibrate, wait?? Yes I have considered engineering bricks but architect wants to see a Padstone. @tony1851 do you know what mix should be used?

 

[^woody^]

What has a padstone got to do with an architect?

And why can't an alternative size, bricks, slab, lintel, plate be used, or rebuilds of a few course?

 

[tony1851]

Design of the beam bearing is the SE's job, not the architect's.
As well as engineering brick, you can also use cut-down pre-cast concrete lintels. Depending on how you arrange it, the padstone does not need to be in one monolithic piece - it can be built-up. It also depends on what size beam(s) it is supporting and how long the bearing of the beam(s) needs to be.
Do not be unnecessarily tied down by what your architect 'wants to see'.

 

[an203888]

Never spoke to a SE or seen any mention of one, just the architect.
Its funny, half the time on here people bleet on about following the specification the architect has set and now you guys say do somthing else.

I realise that there could be other options but the question I am asking is regarding the mix to use and more specifically the aggriate size when casting a Padstone in place. Thanyou

 

[tony1851]

A padstone is a structural item; architects are not usually competent to specifiy on structural matters.
Most likely the architect has picked a size off the top of his head, when in practice you may well be able to get away with a smaller padstone.

Have you considered asking your architect what mix you should use? - he's the one who specified the size, so presumably he should know what load the padstone is carrying and therefore what strength/mix of concrete you need.

 

[kingandy2nd]

...
Its funny, half the time on here people bleet on about following the specification the architect has set and now you guys say do somthing else.

I realise that there could be other options but the question I am asking is regarding the mix to use and more specifically the aggriate size when casting a Padstone in place. Thanyou

Don't bite the hand that feeds you mate. Tony & Woody are trying to give you genuine help to save you time and money...

It may well be that your architect is (or has employed) a structural engineer to give you a specification. The structural calcs for the beams, piers, etc will need to be given to building control so there must be an SE somewhere in your equation whether you know about them or not.

As the requested a padstone that is not and off the shelf size, you would be better off asking the architect (or their SE) to give you the exact detail they want it terms of mix etc in order to meet the specific needs they've designed. Perhaps they will come back and advise you to use engineer bricks, or pre-cast lintels or another solution - don't be afraid to as the question as you've paid them for the service.

Given that you're doing something a bit unusual which needs this non-standard padstone, I would expect that you / your builder should be supplied with plenty of details about how to do the construction itself - not just the beam sizes. Tony did mine specs for me and I've got pages of calcs and diagrams detailing the exactly how the construction should be done, for example:


ps - I don't think many people on here would say to follow an architect's spec. Sometimes the feedback is follow the SE spec. Most of the time the view is that architects are 'building something pretty but impractical to build', and SE's are 'inexperienced and/ or over-engineered solutions to simple problems', more often then not people post up for help when there's no architect, designer or SE involved and they've hit a major problem...just my experience of using this place for a decade or so

Hope this helps...

 

[^woody^]

bleet on about following the specification the architect has set

the question I am asking is regarding the mix to use and more specifically the aggriate size when casting a Padstone

Bleet, bleet, what mix and aggregate size has your architect specified?

 

[an203888]

So no Tony you don't know the answer to my question, that's what I just

Bleet, bleet, what mix and aggregate size has your architect specified?

Nothing yet, I have sent an email asking the question!

 

[dontbelieveawordofit]

don’t see why you just dont shutter it and pour it. you sound confident .
you won’t get a single definitive answer to the concrete mix in case you tw@t it and it falls down.
being as tony1851 suggested you bodge it with cut down precast lintels ,most of which are c40 , lets assume a c40 spec , which you can buy bagged premixed.

 

[^woody^]

The question should be "Who the hell designs a 'L' shape padstone?".

 

[an203888]

don’t see why you just dont shutter it and pour it. you sound confident .
you won’t get a single definitive answer to the concrete mix in case you tw@t it and it falls down.
being as tony1851 suggested you bodge it with cut down precast lintels ,most of which are c40 , lets assume a c40 spec , which you can buy bagged premixed.

This seems like a good solution, just add the right amount of water, mix well, pour, vibrate and let it cure.

Seems like a much better solution to chopping an off the shelf product to fit imo.