small slab

G'day Folks, after some advice

I am laying a small slab 3m x 3m for a small courtyard, which will be under cover. I was originally going to pave, but the coast was way to much.

I have laid a few small slabs before so have no problem doing this one. However I am after a black colour finish and a friend suggested I use a black powder which is sprinkled on at the end and trowelled in, (Oxide I think...)

I have been through all the threads and found a couple on colouring, is it as easy as he says, and if not how can I go about getting a nice even black finish. I am mixing the slab myself by mixer.

Any Advice is appreciated. Ta muchly:D

Might be easier getting a premix delivery, it saves a heap of work. They can add the oxide and get a nice even colour. The other option is paving paint.

Cheers
Pulse

you can throw a mix of stone dust and oxide on the top and trowel it in.If you soread it roughly even to start with,it will be even.

Tools

The best way is to mix it in the concrete before you add the water. But remember if you are going to need more than one batch make sure you can replicate the amount of oxide in each otherwise you will end up with a colour variation from batch to batch. I use a cup measure when doing small jobs myself or as has been said previously get it premixed and delivered.

Good luck with it.

Pete

The best laid plans of mice and men aft gang aglay.... so it's a damned good idea to have a contingency plan. ;)

If you go the "oxide sprinkle" method, I'd suggest you also have some blue-gray(ish) and ochre(ish) oxides to hand. If you're not satisfied with the black effect (patchiness, etc.) you could artistically apply the others for a slate effect... making the patchiness work in your favour.

Just a thought. :)

Thanks guys

it sounds like oxide isn't that easy to apply, and may be more trouble than its worth, the slate effect may work but then again I would know that it is a botched effort on my part. :D

Doughboy, does adding the same amount of oxide work like you said, getting it delivered is too expensive for the small amount I am doing and I am one for saving money where I can. I can add the same amount of oxide (thats not to much of a hurdle) everytime to the load, but sometimes I know the amount of sand/gravel may vary a little. will that effect it.

and all said and done, if the colouring does not work, is painting an option, I get an idea that the paint will scratch easily.

Yours in colour

have a look at http://www.dectech.com.au. They supply oxide powders to professional concrete stencillers.

cheers
pulse

One method you can try which reduces stuff ups on solid colour is a topping dust. Just get a bag of premix sand and cement, grab a cup full (or two, or three) of oxide powder and mix through dry. After slab is poured and screeded but not trowelled throw on the dry mix, rub up with a wooden float then finish off with a steel trowel. The colour should hold as well as mixed in the slab and you will get a good finish with the topping acting as a filler as well.

John

John

Thanks for that advice it seems like it could work, well it sounds easy anyway, so I shall give it a try, I gather, as you said, that I sprinkle it on evenly, covering the slab whilst it is still moist and then finish off with a trowel. Simple:eek:

In regards to the colouring, using oxide, can you use to much or is there a set amount, which would be on the instructions (all else fails read the......)
I have the mentality, that if I want it dark, throw the lot in:D .

but thanks for the advice.

If you want to throw in a bucket of colour go for it, I rate as a concretors back side rather than a concretor so ratio's are not something I have much experience in. The colour does fade a bit and if you are using a colour like black the heavy concentration will still give a good result. I've coloured a few slabs for friends on patios and the like all seem to fade regardless of the colour in the slab or topping coat. The sun has a pretty strong bleaching effect. You can put on a lacquer to hold the colour but that seems to much like hard work to me.

In answer throw the topping mix on while the slab is wet, straight after screeding, if everything has gone a bit dry you can flick a bit of water on with a brush, or a quick sprinkle with a hose if really, really dry.

John.

When you order your concrete ask them to premix the oxide into it. They do black and red all the time so they know what ratios to use and they will be consistent over batches.

Well I thought I would post a pic of the almost finished slab, I went the way of Johnc, mixing the oxide with dry sand and cement.

As I was sprinkling it over I realised I made a basic error, (one of many I might add) and that was rushing the job to get it done, had I waited until I had a roof over it, I would have avoided the problem of precipitation late in the afternoon.

I had poured the slab and just sprinkled the dry sand/cement and oxide mix over it, and started the trowlling, mmmmmm looks good I think, at the same time casting an eye up to the dark and stormy skies, on finishing, I looked at it and with glee, thought, "God I'm good"

it was at this point that the heavens, in their wisdom, started to bring me back to earth, with the rain, came the roof run off, so not only having to contend with rian, I had the run off to deal with, so with a lot of grunting, pain and frustration I was able to cover it with plastic without touching it. (Not bloody easy)

And you can guess what happened next, it stopped raining. Aaaaaaaargh.
So the next morning I pull of the plastic and decide I don't like the finished look, "bugger it, paint the ffffing thing." So i grab the large brush and proceed to brush it, lol and behold I end up liking it.

So all I have to do now is coat it in a finish, and if I don't like that then I will paint it. Around the edge will be some cute stones, ala Back yard Blitz.

Looks great! like the stones idea. Goes well with the black pergola.

Cheers
Pulse

Looks fine, pity about the rain, it seems to have a sixth sense sometimes.