Polished concrete worktops....How to?

[cannyfradock]

Members & Mods...

I know quite a few of you have cast and polished your own concrete worktops. The most recent Vault oven build by DuncanM has a beautiful polished concrete worktop..



...this is the link to that build.. ukwoodfiredovenforum.proboards.com/thread/136/new-build-woking?page=8

I have been asked to produce something like this on my current build.. ukwoodfiredovenforum.proboards.com/thread/1811/kate-humbles-90cm-pompeii-monmouth

Could anybody please tell me.......

What suitable stone/glass can be purchased for a mix of perhaps 2 colours? Garden centers have a good choice of those 25kg bags but I'm not sure what is suitable.

Apart from the decorative stone(s) I'm thinking of using 6mm granite chippings, sand and normal opc cement at ratio of 4:2:1 for the concrete bulk of the slab.....would this be OK?

Added complication....I've been asked to inlay 3 letters in the polished concrete. I hope to do this by using different coloured stone, but how do I keep the letters in place when pouring the slab (I'm hoping Duncan can find a solution for me)

I intend using the same system as Duncan i.e....melamine board with triangular quadrant on the edges, with fine mesh re-bar. I'll probably just use an electrical sander (without the sandpaper) to vibrate the shuttering.

Any suggestions or tips will be gratefully received.

I've looked on Utube but the vids I have seen haven't been very good.

Terry

[rivergirl]

I remember asking about this years ago on the old site. Hopefully will be able to get it done when I do my new build .......,.......

[spinal]

I wanted to do this on mine, and tried a few sample bits (pictures on here somewhere I think) - for the inlaid stuff (I was going with a triforce) I simply used some spray-on glue, and glued the bits to the board. Then poured gently. The glue gets sanded off in due course.

Regarding what to use, I found that just about anything works - but the more porous stones need a sealant afterwards.

M.

[cannyfradock]

When (or maybe if) I get round to doing it I'll post lots of pics...the good, the bad...and ugly (hope not)....maybe come in handy for you Lesley when you cast yours......I'm bound to have a few probs...and I'll post them.

Thank-you M....I was thinking along those lines but was worried that the adhesive used wouldn't sand off. Can you please (it'll be quicker for you to find it) post the link of your thread with this topic in it. I've seen quite a few threads with polished concrete as a topic, but finding them is a nightmare.

[DuncanM]

Hey Terry,

I've got lots of advice!

As mentioned in my post, I used pre-bagged (and most importantly - high strength) concrete. This product: www.travisperkins.co.uk/p/hanson-40n-concrete-mix-maxipack/804542/3893445 I'd be sure - if you are mixing it yourself, which appears to be the case, to use a high strength cement, not your standard portland. It will cost a bit more but worth it in my opinion. ALL pre-bagged concretes in the US where this is "normal" are high-strength mixes.

My mix was this:
For every 2 x 25kg Prebagged Hanson 40N concrete
100ml Sika Black liquid colouring
20ml Sika concrete waterproofer
100ml superplasticiser

I could only find the superplasticiser online (ebay I think it was). You may have more luck being in the trade already. All I could find was "normal" plasticiser, and to ensure a very strong mix I wanted to reduce the water quantity as much as possible.

You'll be absolutely fine using an orbital sander to vibrate. Just make sure you keep it on each part for a good long while. I still had plenty of air pockets with my petrol poking vibrator.

How close are you to Woking? Reason I ask is that I have LOADS of spare glass, of both colours, you'd be surprised how little you actually use. Do not buy big bags (25kg) at all.

If you follow my photos it shows it fairly well how I constructed it. Here's my guide for you.

1. Make form using melamine board. You do not need to use mould release oil when using melamine.
2. Sort out reinforcing as necessary - depending on if it's a cantilever like mine or a beam. Any thinner than 2" and you shouldn't use normal rebar mesh in my opinion as you run the risk of ghosting. Use brick ladder, it's perfectly suited and should be easy for you to get. It was a pain in the backside for a non-tradesman like me to get hold of though.
3. Use either silicone caulk, or a spray adhesive to stick the aggregate you want placed to the bottom of the form. REMEMBER IT'S INVERSE! Once this is done, pour the concrete and add the rebar.
4. Allow to dry for 2 or so days, flip form over (carefully). Remove the melamine mould carefully.
5. Start grinding/sanding/polishing immediately with a 50grit. The sooner you start doing it, the less time and effort it'll take.
6. If using a sealer like mine, you can leave the finish at 50 grit. It'll create it's own smooth surface.
7. After 2 weeks+ lift and secure into place.

It really is pretty simple. Just sped the time making the form right, and make sure you are happy with the placement of the stones to form the letters as you glue/silicone. (I used silicone - but make sure it's as absolutely thin as possible - as you'll need to grind it off later.

Also about the sealer - I could probably sell you enough to cover my whole countertops again at a cheap price (enough for 2 coats 4M2).

So the offer is there:
If you can and want to come and visit, you can inspect mine, and buy some glass and sealer for cheap.

If you update the build thread with any problems/specific questions I'd be happy to post replies when I see them.

I don't think many people have seen my countertops on my post though, only you Terry commented.

[edinburghman]

DuncanM wrote

"Sort out reinforcing as necessary - depending on if it's a cantilever like mine or a beam. Any thinner than 2" and you shouldn't use normal rebar mesh in my opinion as you run the risk of ghosting. Use brick ladder, it's perfectly suited and should be easy for you to get. It was a pain in the backside for a non-tradesman like me to get hold of though."

Is this the stuff - www.screwfix.com/search?search=brick+mesh if so, what do I need please, anyone?

[DuncanM]

Hi Edinburghman it's the stuff that looks like a little ladder, NOT stuff that looks like a mesh.

look at the link below, it's the top bit (power-tie Flat Wire Ladder Reinforcement) with the different coloured versions denoting the size of the wire.

www.expametconstruction.co.uk/masonry_reinforcements.html

[matthewcove]

Hello,

I was wondering if anyone seals the concrete or puts additives in the mix to make it more weatherproof? The worktops I have made for my indoor kitchen have a PVA like additive, plasticisers and are sealed with a 2 part clear urethane. Plasticiser will certainly help get the air bubbles out more easily

Matthew

[DuncanM]

Yes as I mentioned above I use a waterproofer, superplasticser and when it was all finished, I applied a sealer.

[zack]

hi duncanm i'm looking for a sealer for my concrete worktops, please could you give me the name of the one you used.

[DuncanM]

Hi Zack,

Firstly, I found it difficult to get as much clear advice around sealers as people in the US seem to be able to get. There doesn't appear to be many off the shelf products for your average joe. That being said, the one I went for was this:

DekoSeal + Biomaster antimicrobial agent from DekoFlake.co.uk

I emailed [e-mail] asking for a concrete sealer, and I had phone calls and skype conversations with two guys, Malcolm Davies and Keith Wilson, both of whom were excellent. I explained I was way above my depth and outlined what I wanted - they explained in terms I could understand, and even gave me skype chats to explain the application for such a novice.

Essentially I couldn't speak any higher of the DekoFlake team or product. It's been outside for 6? months now with zero wear.

I'd be interested to see what you are doing/planning Zack. Any photos to share?

[zack]

hi
thanks for your reply,sounds very promissing as you said in the uk there doesn't seem to be very much available.
i 've just finished making concrete worktops and sink for an indoor kitchen, and i'm now building the cabinets from osb, i've got some steel splash backs to put on too, we want an idustriel loft look...
i'll post some pictures asap

[nulph]

May 8, 2014 19:58:39 GMT DuncanM said:

Hey Terry,

I've got lots of advice!

As mentioned in my post, I used pre-bagged (and most importantly - high strength) concrete. This product: www.travisperkins.co.uk/p/hanson-40n-concrete-mix-maxipack/804542/3893445 I'd be sure - if you are mixing it yourself, which appears to be the case, to use a high strength cement, not your standard portland. It will cost a bit more but worth it in my opinion. ALL pre-bagged concretes in the US where this is "normal" are high-strength mixes.

My mix was this:
For every 2 x 25kg Prebagged Hanson 40N concrete
100ml Sika Black liquid colouring
20ml Sika concrete waterproofer
100ml superplasticiser

I could only find the superplasticiser online (ebay I think it was). You may have more luck being in the trade already. All I could find was "normal" plasticiser, and to ensure a very strong mix I wanted to reduce the water quantity as much as possible.

You'll be absolutely fine using an orbital sander to vibrate. Just make sure you keep it on each part for a good long while. I still had plenty of air pockets with my petrol poking vibrator.

How close are you to Woking? Reason I ask is that I have LOADS of spare glass, of both colours, you'd be surprised how little you actually use. Do not buy big bags (25kg) at all.

If you follow my photos it shows it fairly well how I constructed it. Here's my guide for you.

1. Make form using melamine board. You do not need to use mould release oil when using melamine.
2. Sort out reinforcing as necessary - depending on if it's a cantilever like mine or a beam. Any thinner than 2" and you shouldn't use normal rebar mesh in my opinion as you run the risk of ghosting. Use brick ladder, it's perfectly suited and should be easy for you to get. It was a pain in the backside for a non-tradesman like me to get hold of though.
3. Use either silicone caulk, or a spray adhesive to stick the aggregate you want placed to the bottom of the form. REMEMBER IT'S INVERSE! Once this is done, pour the concrete and add the rebar.
4. Allow to dry for 2 or so days, flip form over (carefully). Remove the melamine mould carefully.
5. Start grinding/sanding/polishing immediately with a 50grit. The sooner you start doing it, the less time and effort it'll take.
6. If using a sealer like mine, you can leave the finish at 50 grit. It'll create it's own smooth surface.
7. After 2 weeks+ lift and secure into place.

It really is pretty simple. Just sped the time making the form right, and make sure you are happy with the placement of the stones to form the letters as you glue/silicone. (I used silicone - but make sure it's as absolutely thin as possible - as you'll need to grind it off later.

Also about the sealer - I could probably sell you enough to cover my whole countertops again at a cheap price (enough for 2 coats 4M2).

So the offer is there:
If you can and want to come and visit, you can inspect mine, and buy some glass and sealer for cheap.

If you update the build thread with any problems/specific questions I'd be happy to post replies when I see them.

I don't think many people have seen my countertops on my post though, only you Terry commented.


DuncanM

You mention in point 2. that getting the ladder wire was a pain, where did you source it in the end? - having the same problem. - was looking at using a strong mesh as an alternative (http://www.tfmsuperstore.co.uk/shop/weldmesh-general-purpose-panels-weld-mesh-galv-2-x-2-x-10g-x-4-x-8-13756.html) but the tensile strength of ladder wire is supposed to perfect - so i would prefer it if i can source it.

[DuncanM]

I contacted the manufacturer (Expamet Building Products - expamet.co.uk) who advised it could be ordered through a number of building merchants, I went with Travis Perkins in the end. Problem was, I had to pay for delivery to the store which was in the region of £50 if I remember correctly, and then delivery to my house, so very expensive and a pain in the arse.

[nulph]

Thanks for the pointer!