Urgent concrete advice wanted

We've been dudded again with a concrete slab. Not long ago we paid through the nose for a slab (25 SQM for $1600) done by a "friend" who is a professional concretor.

This time we asked a neighbour who is a reasonable concretor to finish off a smaller slab for us. We did the boxing and so on, and we just wanted him there to finish it for us on the day.

Despite the best intentions, the work was a bit beyond him (he's 65 and it was damned hot and so on). Now we're left with a slab that is OK in form, but the surface finish is terrible. I think our neighbour overworked it and it now has an inconsistent surface and a few holes, or low spots. It's in a prominent position at the entry to our house.

The neighbour says that he can fix it with slurry, but my own experiences tell me that this is a bit suspect (three days after the slab was poured).

What shoould we do?

Paint the holes with Bondcrete and fill with a slurry/bondcrete mixture?

Can we use one of those concrete sanding machines?

????????

G/day Rossluck,I think the best option is to "top"it if you are not inclined to change the surface material (tile etc)You would need an experienced tradesman to do it though as you are working with a fairly thin coating.They used to do quite a bit of it years ago on verandahs,steps etc but it is probably too labour intensive these days.It is a good finish when done correctly but as I said would need to be done by a good "old style" tradesman.Regards Terry

There are miles of different topping options available these days from your tried and true pebblecrete to new coloured and faux paved finishes.
It would seem a shame to spend good money after bad so to speak.
I would do some research on acid etching etc or the grinding that you mentioned and try to make a unique feature out of it, for a budget price.

Just thought that one option I have seen done is to paint the concrete with concrete coloured paint. I kid you not. the stuff I have seen used was a thick membrane type paint.
Try NuTech paints or Durobond paints in Sydney

Thanks fellas. One thing I forgot to mention is that whatever is done on this slab (17 sqm) needs to be continued all around the house. You can see my dilemma :mad: .

I didn't mean the new type of acrylic type products that they manufacture these days (Shieldcoat,Concoat,Stencilcrete,etc,etc)I meant the old style "topping"with a sand and cement mix.Maybe the fellow who did the job is familiar with it even if he can't do it for you.I'm sure if you ask about someone would be familiar with the method.I don't know if it's the best way out, but it could be a way out for you,as the colour won't vary much from normal concrete.Regards Terry

Thanks Terry, (by the way, SWMBO is from Wagga).

I know what you mean about the topping option. We have considered it, but some concretors have warned us that it doesn't work too well. I don't know. I can't begin to tell you the "concrete story" from around here, we haven't had much luck. This slab is just the latest disaster.

What I'm considering at the moment is a spray application of the stuff they use on stencils. I'd be happy to buy a spray gun and the coating, but I want to find out more about it.

The reason I wrote "urgent" in the title of this thread is because my poor ol' neighbour might turn up with a bucket of slurry ....:eek:

A topping coat on a three day old slab should give a solid bond. Depends on the mix but it should be strong enough to drive over etc, if it is another disaster get a spade under it the next morning while it is still weak and it will lift off and you will be left with the same mess you began with. You probably don't have anything to loose. My parents driveway was done that way thirty years ago and it is still as good as new.

John.

The guys that did the paving around my pool put in place over the concrete a thin but rich layer of bondcrete/cement paste very watery in consistency just brushed on with a scrubbing brush to give the bond face.

They then put onto this the cement mortar (or slurry in your case) which was a medium river sand - cement mix with some bondcrete added to it.

Obviously more cement gives a stronger and darker product.

They claim a jack hammer will be needed to remove any pavers.

It all looks rock solid - i know they are good tradesmen from recommendation.

So I would say you can apply a topcoat to match what you have in place with the right preparation to the existing concrete and the topping.

If you are interested in enhancing the bond with the existing slab as it is still pretty green you could use a water blaster to remove the fines back to aggregate and give an irregular surface and help bond the topping and maybe even lower the slab top so that once the topping goes onto this it is up the the top level you were originally after.