Polishing concrete samples : guess whose job it is?

[Crofter]

Very interesting topic. I am contemplating concrete for the worktop, but I was going to just use snowcrete, pour it upside down in a mould, and vibrate the heck out of it with my vibrating poker. Grinding it down by hand sounds a bit tricky!

 

By the way did anybody see the episode of 100k house where the two guys poured a concrete kitchen island? It was their first ever DIY concrete pour and it was... interesting. Presenter said it looked rustic and honest, or similar euphemisms; I would have been angle grinding it into little bits and throwing it a skip before anybody saw it!

[PeterW]

47 minutes ago, Crofter said:

Very interesting topic. I am contemplating concrete for the worktop, but I was going to just use snowcrete, pour it upside down in a mould, and vibrate the heck out of it with my vibrating poker. Grinding it down by hand sounds a bit tricky!

 

 

Cheap formica that has lots of wax on it works really well - it is the corner radius that causes problems normally with any moulding. Rebar in the back and plenty in the edges gives the reinforcement. 

 

There are some really good videos on YouTube that show how it's done from the inside out and they start with a pretty flat surface and then polish rather than grind.

 

This is one - plenty more though 

 

Edited August 17, 2016 by PeterW
Added link

[Ferdinand]

4 hours ago, recoveringacademic said:

Folks, the guy who is coming to lay the concrete said to me yesterday  that he'd put some  '...fiber...' in it to save me putting reinforcement in it myself. At the time I paid no attention. 

 

What does he mean by 'fiber' ?  [  @SteamyTea above]

 

I think my fibres came from Wickes.

 

BTW you need very little of it.

 

Mine came in a packet smaller than a bag of salted peanuts, and I seem to remember that it cost £3.50 or so, and were more than enough for a 25sqm 125mm slab. Check your numbers or you may have half a kilogramme kg of fibres to leave to your grandchildren's grandchildren, minus the 4.5g you have used.

 

Ferdinand

Edited August 17, 2016 by Ferdinand

[ToughButterCup]

3 hours ago, jack said:

This sort of thing: [...]

We have it in our screed in a couple of rooms.  

 

Given my guy's approach to the production process ....

 

at the time, I joked  that I suspected him of getting cheap fiber from the local charity clothing shops. Or his wife's 'smalls' drawer.

Nothing so prosaic; I am glad of the explanation. But I'll check for M&S labels sticking up out of the mix.

[PeterW]

Fibre can sometimes cause the concrete to thicken so you will need to keep an eye on the slump and how fast they work the slab. It's usually so fine it doesn't cause problems with polishing as the fibres get trimmed off by the process.

 

For the added price per load my supplier gives, it may even go in the foundations ..!

[Crofter]

4 hours ago, PeterW said:

 

Cheap formica that has lots of wax on it works really well - it is the corner radius that causes problems normally with any moulding. Rebar in the back and plenty in the edges gives the reinforcement. 

 

There are some really good videos on YouTube that show how it's done from the inside out and they start with a pretty flat surface and then polish rather than grind.

 

This is one - plenty more though 

 

 

Thanks for the link, I hadn't really looked into this much before now- I had done some reading which suggested a DIY worktop was certainly feasible.

I am quite surprised by how dry the mix is. I had assumed that you would use a fairly normal mix that would flow, especially with a bit of vibration. 

[jack]

As promised, some photos of our concrete.

 

First, our entrance and hall:

 

 

 

Next, a couple of photos of the the concrete itself:

 

 

 

One thing you need to be aware of if you're getting it polished after your studwork goes up is that the power floating and then polishing doesn't give you the same effect at room edges as in the middle.  We were warned about this, although I must say that the differences extend much further into the room than I expected.  These are two of the worst affected areas:

 

 

 

We're still happy with the result though.  Concrete is an industrial product, so an industrial result is fine.

 

From memory we paid around £90/sqm laid and polished.

[Ferdinand]

Having just chased a small squirrel off the cat's lunch, I am in the mood to use squirrel tail hair.

 

Though the (18 yo) cat caught the squirrel's sister yesterday, so perhaps it is revenge.

 

Ferdinand