Polishing concrete samples : guess whose job it is?

[ToughButterCup]

Right first time.

 

I'm making  a set of foot square samples of concrete so  @MrsRA can  choose her favourite mix of glass and concrete, and then agonise over which colour she wants. 

 

I have yet to polish one sample, let alone the half dozen I'll need before making a choice. I have a decent Bosch angle grinder. 

My usual approach is to look at videos and I fancy this approach

 

But I'm not a fan of mixing sparks and water.

Advice, please!

[Construction Channel]

wear wellies 

im gonna have to do it one day and i hadn't really thought about it, 

be careful with the water, possibly rubber gauntlets?? 

 

I'm probably not the best guy to ask

[Calvinmiddle]

I thought the important thing was to have a grinder like he had that supplies water as well.

 

i the early days of our build I wanted to make my own worktops.  I found one like it here

[PeterW]

Standard grinder at 10k rpm will destroy the diamond pads - 2-3k at most, even slower with coarse stuff otherwise you will just rip the pads to bits. 

 

And lots and lots of water ..! 

[TheMitchells]

Wow, I am almost convinced by that video - it looks really good. The OH is quite keen on concrete but I thought it would look horrible. I may have to reconsider.

[jack]

We have polished concrete on top of an MBC slab. Let me know if you want some photos.

[jfb]

If it is only a few square feet you could always just do it dry.

 

if you are going to try and expose the aggregates it might be easier to use pretty fine stones like in the example in the video. If you have normal ballast it will be a lot more work.

[sussexlogs]

polished concrete shower tray

[Calvinmiddle]

1 hour ago, jack said:

We have polished concrete on top of an MBC slab. Let me know if you want some photos.

 

I'd like to see some photos, did you get it polished or just a really good power float

[ToughButterCup]

If only I had known how much hard work there is in polished concrete.

@MrsRA probably did before she fluttered her eyelids.  Still, I've got be kept off the streets somehow.

 

6 samples being cast this weekend and the polisher has been ordered. Thought I'd make the samples into tie-downs for tarpaulins by sticking a bit of bent re-bar in the top. No point in wasting good concrete is there?

 

Piccys to follow.

[SteamyTea]

I can understand using polished concrete for a floor, but what is the advantage for smaller areas like counter tops and around showers?

I must be easier to get a professional to knock up something from a suitable stone in his workshop.

[Barney12]

1 hour ago, recoveringacademic said:

If only I had known how much hard work there is in polished concrete.

@MrsRA probably did before she fluttered her eyelids.  Still, I've got be kept off the streets somehow.

 

6 samples being cast this weekend and the polisher has been ordered. Thought I'd make the samples into tie-downs for tarpaulins by sticking a bit of bent re-bar in the top. No point in wasting good concrete is there?

 

Piccys to follow.

 

One on each foot and you should sink nicely when you next upset @MrsRA  

[Barney12]

55 minutes ago, SteamyTea said:

I can understand using polished concrete for a floor, but what is the advantage for smaller areas like counter tops and around showers?

I must be easier to get a professional to knock up something from a suitable stone in his workshop.

 

I have to agree. Polished concrete does look lovely when done properly but it's a huge amount of work and skill to make something like a worktop look good. 

 

The issue is you just can't keep a handheld polisher with a small head horizontally aligned with the peice to create a good result. The pro's polish on a huge bed with a fixed arm. 

 

Ive been lucky enough to visit the factory of these guys https://www.mass-concrete.com and they turn out some stunning work in concrete. 

Edited August 16, 2016 by Barney12

[jack]

9 hours ago, Calvinmiddle said:

 

I'd like to see some photos, did you get it polished or just a really good power float

 

Bit of a long story, but the slab concrete didn't set right (combination of unexpected squalls followed by freezing weather in the following two days).  MBC suggested raising the entire house by a stud width (38mm) and then flowing in a screed.

 

In the end, we decided to go with concrete.  We'd allowed for 25mm floor coverings, and that plus the 38mm gave us just enough to squeeze in ~65mm of concrete which was then power-floated to within an inch of its life and then polished and sealed.  65mm is less than the recommended minimum of 75mm and we do have a couple of cracks.  Still worth it.

 

I'll post some photos later.

[Ferdinand]

I would think that the time in the setting process is crucial.

 

If yuo start while it is 6 hours hard, rather than 6 days hard, does that help?

 

I always think that it would be nice with marbles.

 

Ferdinand

 

Edited August 16, 2016 by Ferdinand

[ToughButterCup]

4 hours ago, SteamyTea said:

I must be easier to get a professional to knock up something from a suitable stone in his workshop.

 

Easy? What's the point?

Hard? Needs energy fizz, effort..... worth it.

 

 

[jack]

2 hours ago, Ferdinand said:

I would think that the time in the setting process is crucial.

 

If yuo start while it is 6 hours hard, rather than 6 days hard, does that help?

 

From memory, the guys that did ours said it's best to let it go off for a few days after power floating, but no more, before polishing.  There's a balance - you want it hard enough to take a polish, but not so hard that polishing takes forever.

[ToughButterCup]

Thanks Jack. Ian

[Stones]

I was visiting a WW2 gun emplacements the other day.  Inside, was a beautifully cast concrete worktop.  An everyday utilitarian surface put in quickly with an expected service life of only a few years, looks, 75 years on, perfect.  I've seen other wartime examples up here of worktops with drainage grooves cast into them, concrete 'kitchen' units with caithness stone roof slate shelves.  All of it done in a hurry with what was available.  Shame those same skills are not readily available today.

[SteamyTea]

2 hours ago, Stones said:

Shame those same skills are not readily available today.

Or the asbestos fibres that hold is together so firmly

[janedevon]

Ours was laid 2 weeks ago 3 more weeks until polishing takes place

[ToughButterCup]

12 hours ago, Stones said:

I was visiting a WW2 gun emplacements the other day.  Inside, was a beautifully cast concrete worktop.  An everyday utilitarian surface put in quickly with an expected service life of only a few years, looks, 75 years on, perfect.  I've seen other wartime examples up here of worktops with drainage grooves cast into them, concrete 'kitchen' units with caithness stone roof slate shelves.  All of it done in a hurry with what was available.  Shame those same skills are not readily available today.

 

That's really interesting. I wonder what effect that level of permanency would have on the kitchen furniture sector?

[ToughButterCup]

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]

 

[SteamyTea]

Concrete is a composite material i.e. made of many things.

It is not unusual to put chopped glass fibres in it.

Hemcrete uses hemp fibre, CRP uses carbon fibre, brake pads used to use asbestos, really all comes down to the properties wanted.

[jack]

This sort of thing: http://www.lbsbmonline.co.uk/product-details.asp?Auto_ID=193455

 

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