Concrete worktop

[ftacarpentry]

Morning!

I have made an island unit that requires a worktop at 1300x1300mm, and the client is after concrete.

I have a good working relationship with my clients, and they are hoping to achieve a rustic looking worktop (I.e. Not polished to a mirror finish, without any air pockets etc.), I have also explained that I haven't done this before and it will be a bit of an experiment and they are fine with this.

Anybody done this before? Any tips etc?

The top will be circa 50mm thick. I plan on using rebar/remesh and some glass fibres for reinforcement. I understand that I need to keep the mix as dry as possible to restrict shrinkage/cracking but I can't really ascertain the best mix to use, or even really which aggregate would be best?

All advice appreciated!

Ta,

Pete

[mark270981]

This will be interesting work.

https://www.youtube.com/watch?v=U7GuE2O2DAo

will this video help?

[mark270981]

https://www.youtube.com/watch?v=HNmJr7cQlkQ

[furynaturre]

Go for it, it's not that hard to do, but the maintenance does have to be good, the only food safe not colouring sealer I found was Fila Hydrorep

http://www.tilecouture.co.uk/product-ca ... oC017w_wcB

I've attached some pics of a kitchen I made recntly, flakey was the name of the game!

Super plasticisers and loads of vibration when in the mould are your friends. Watch the Vids Mark-Numbers posted.







Just have a go, it's good fun

James

[houtslager]

you have two options - in situ or in your shop/in the clients' garden
natural colour or coloured, if the latter then you need to use white cement dust, mix with sand / water / and colouring powder of choice.
Mix to a stiff mix, and "pour "

Note to remember - BLOODY HEAVY ! once set, and will take more ppl to lift into place then you think DAMHIKT !

For any through the top fittings, reduce the thickness by 50% from the underneath, this will allow you to use standard tap / waste fittings.

Don't forget to post pics - or it never happened

IF more info needed - just shout out loud, I'll try to help more.

hth

Karl

[tusses]

I've seen it done on telly ! lol

looks easy

[ftacarpentry]

Thanks for all the responses.

Mark- cheers for the links to those videos, they were interesting viewing.

James- that whole kitchen looks pretty amazing. The worktops are incredible, but is that also a workbench with a hob set in it?!!

Karl- cheers! I'll be sure to post pics as progress occurs... It's pretty much just a 1300mm square, but I'm sure I'll find a means of turning it into hardcore!

Tusses- yeah, saw it in TV too... Looked easy but now push has come to shove I'm a little more wary! Just got to resist the urge to stick all sorts of objects in it...

Thanks again gents!

Pete

[ftacarpentry]

Me again!

I still can't seem to settle on a suitable ratio for the mix...

Currently I'm thinking one part cement, one part sharp sand (to keep it a bit rustic and not too smooth), three parts builders sand.


Does that sound about right?

Cheers!

[tusses]

without aggregate, it's just mortar ? surely ?

I'm sure the one I saw used pea gravel

As mentioned before, plenty of vibration to smooth the top surface

[furynaturre]

You will need an aggregate, concrete is only strong because of the aggregate.

You need as much big stuff as you dare, without it jamming the mould and not allowing the fat to get to the outside. You are basically looking at 4 or 5 to 1 mix

For your top... 1.3x1.3x50mm

about 25kg cement

100kg gravel your choice, 10mm pea shingle is fine, you could use some silica fume as well but it's a faff to get hold of. Any aggregate a good deal larger than the sand will be ok, Seen some done with recycled glass!

50kg sharp sand

That's About 2 mixer loads

15 litres of water, with super platiciser this will vary depending how wet the sand and gravel are.

Add fibres

Dry enough it doesn't slop about, wet enough to move around. Neatly silicon the corners, knock the living daylight out of the mould (Best made of MFMDF or MFC) constantly, if you think you've knocked it enough, you haven't, keep knocking.

Trowel the back of the as it cheeses up.

Have a go, make the form nicely and if it goes wrong you can have a couple more goes.

[ftacarpentry]

Cheers James- I had hoped the sharp sand would be aggregate enough, but had a feeling I was wrong! Sounds good, I'll have a stab in the next week or so.

This is going to be heavy!

Thanks,

Pete

[colg]

There's a good book by a guy called FU-TUNG CHENG called concrete countertops - now why do I thinks it's a yank book???

[ftacarpentry]

Well... after hours spend on my knees (ahem) she left the shop and is proudly sat atop the island...

All the pics look kinda the same, but since everyone was so helpful, thought the least I could do was post a couple of pics!

Former made from Melamine faced chipboard, on some 6x2"s that I had flattened and screwed into a rigid torsion-box type o' thing...



I had made a grid of rio-rods (12mm diameter) tied on approximately 200mm centres. Dumped about an inch of muck in the former, tamped it like crazy, then floated the reinforcing on this, with some wire tied to the sides to stop it sinking when I gave it a good old shake! Dumped the rest on top to give me circa 50mm of 'depth'. The mix was as advised... three bags of pea shingle, three bags of sharp sand, a bag of dust, and as little water as possible.

I thought my vibrating device was inspired... an sds drill set to chisel mode with a very blunt chisel in it held against the former.



After about 10 days, popped the sides off the former. Couldn't bring myself to flip it over... so left it another 5 days...



Was really pleased to turn it without it folding in half, but initially concerned about the 'ghosting' of the rio rods... Left it another 5 days!!!

Spoke to an incredibly helpful chap at ATS diamond tools, who talked me through the polishing process, selling me the bare essentials to get it done without going bananas and buying all the gear.

I managed to use my electric polisher (grinder is too fast) with their copper-bonded discs (4") with just a brush to sluice water over the surface.

Boom!


As always... handles to follow!!!

Thanks again to all of you for your help.

[chippy1970]

Nice job turned out well. Looks really crisp, is it ?

[ftacarpentry]

Thanks!

It is crisp, but not without air dimples and the odd pin-hole. Fortunately my clients wanted a more rustic look, so SUPER crisp wasn't a requirement, and I only needed to polish it to circa 200/400 grit for a honed finish.

If I was going for a flawless finish, I would use densifiers in the mix, and make sure I could get under the whole former to vibrate it...as I did it on the floor I was limited to only knocking the edges.

Pete

[PABLO123]

Well done that man, super job

[chippy1970]

I like it when they put glass, marbles and bits of tile in the mix. Looks amazing when they're polished up but I bet they're a real pain to do.

[mcluma]

real nice job

I like it

[mark270981]

I like that a lot - very nice work.

[houtslager]

good un

[Neil_C]

Beautiful job, I really like it.

[siafins]

Nice job of that! Really like it.

[ftacarpentry]

Thanks for all the thanks!

I am gagging to have another go now...

[promhandicam]

Hi Pete. Odd question, but are you from the Bexleyheath area by any chance?

[ftacarpentry]

No... Afraid not! I'm based just outside of maidstone.

[billybuntus]

Nice effort. Not my cup of tea but I can see the appeal.

I thought you'd snook in and cleaned my kitchen floor for a second when I first saw it. I have exactly the same floor. Could you ask your client what they've sealed them with?

Mine never look that good.

[emir01]

@ftacarpentry

Awesome work. I just wonder if you polished the edges on the top? I think that the edges would be very sharp if they are not grind a little bit.

[Meccarroll]

Very nice, thank's for posting.

Mark

[asselin22]

very good job, i love it

[MikeRotherham]

That looks really good.