The Brew Cabin

I had a 9 section exposed aggregate patio poured and the last section set before the aggregate was added. The contractor dug about 1 inch off the top and returned the next day to add fresh concrete and aggregate to top off the slab. Am I going to have problems with this down the road and should I insist the section be removed an completely redone?

It's impossible to say without seeing the work. It may work, it may not, but from this end of a computer monitor, I could only guess.

However, I'd be somewhat concerned about that 1 inch (25mm) topping layer - that's not the 'official' way to re-do a failed section.

Could you let me know what the 'official' way is?

The conractor did not put the 25 cm topping on, but is waiting a day then using a polymer bonding agent and then doing so.

He also put on a retardant to expose the aggregate after an overnight period (this morning) -- the retardant "did not work" according to him and he is returning tomorrow with a sandblaster. It already looks like he has dislodged some of the aggregate in spots in trying to aggressively brush the surface with a green liquid.

Any suggestions?

I am fearing I will have to pay to brick over the work or get a jackhammer out and remove 40 square meters of concrete that's 200 - 250 cm thick

The 'official' way would be to break out the failed concrete and start again. If the rest of the pavement has been poured and had the surface aggs exposed in this way, then doing one section as an 'overlay', whether it's bonded or not, is likely to result in a different-looking finish, if only because of the difference in concrete depth.

I'm a bit confused about the methodology you report. I read it that, the concrete was poured, left overnight and the retarder (which is probably Rugasol) was applied the following morning. If that's what happened, then the retarder didn't fail - it never stood a chance! How can it retard the hydration of a concrete that has already hydrated?

You should get your contractor to indemnify you, in writing, in case their planned remedial work doesn't turn out as expected. I can't understand why you should be expected to fork out to rectify work that they have managed incorrectly. If the contractor believes it's the retarder that's at fault, then they should bring out the Tech Rep for the retarder manufacturer and let them explain why it failed. While they're there, they could pay for the remedial work too, but I don't believe for one minute that it's a problem with the retarder. I've been using them for 20-odd years and I've never known them not to work!

Finally, you've not quite got the hang of metric units - I doubt very much that your slabs are 200-250cm thick! I think you mean mm, as 250cm is 2.5 metre is around 8 feet! :)

Tony,

Thank you for the information. Here in California, we do need 8 foot thick slabs to avoid cracking in earthquakes. I did mean to say 250 mm not cm, but shouldn't have made the error, esp. since I was trained as a scientist and am quite familiar with the metric system. But, we don't get to use the metric system much over here since we still have a fondness for the English system.

The contractor did apply the retardant on the afternoon that the slabs were finished, but I suspect it was not applied properly or he did not use the right technique to expose the aggregate since many of the stones were dislodged.

The slabs are a mess and the contractor has apologised and admitted he had too few crew to do the job and the timing of pouring, adding aggregate, putting on the retardant, etc. was not done properly. His main expertise is supposed to be stone masonry and he has agreed to put a brick veneer over the whole patio salvage the project w/o having to remove the slabs.

Anything special that I should look out for in looking over the next phase of setting brick on a mortar bed over concrete?

I never realised your were in California: you hid the accent pretty well!

The measurements are not the 'English system': they're "Imperial" - that stops the Welsh, Scots, Indians, Canadians, South Africans etc. from being overly offended! ;)

Anyway, back to the job in hand. The contractor now proposes to lay a rigid brick pavement over the bollixed concrete. That's fine, as long as you're happy with it. The only caveats I'd mention are the choice of brick and the bedding/jointing. Have you seen what's on offer and has the contractor much experience with this paving method?