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Matching Existing Exposed Aggregate Driveway

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  1. #1
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    Default Matching Existing Exposed Aggregate Driveway

    Hi,

    I'm widening my driveway at the top where it turns into the carport. The existing surface appears to be exposed aggregate concrete, approximately 40 years old. I'd like to match it as best as possible. I'm thinking of using the 1, 2, 3, ratio of cement, sand, stones.

    My questions are:

    1. How long after I've poured the mix should I hose off the top layer to expose the stones?

    2. Do I need a high pressure cleaner or can I use the jet on a garden hose?

    Thanks in advance.
    VG

  2. #2
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    You can get an acid?/retarder that you spray on top of the slab before it goes off which prevents the top couple of mm from going hard. Then you hose it off next day.

  3. #3
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    Quote Originally Posted by stevoh741 View Post
    You can get an acid?/retarder that you spray on top of the slab before it goes off which prevents the top couple of mm from going hard. Then you hose it off next day.
    Thanks Stevoh, I'll give it a try.

    Cheers
    VG

  4. #4
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    let me know how you go, I'm planning to do one next week

  5. #5
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    After you trowel the concrete, spray on a sugar/water mix to prevent the top going off. Then you can let it go hard enough to walk on before you hose off. You can use a garden hose if you hose off early enough, if it's gone off a bit too much, get the gerni out.

    1 x 1kg bag raw sugar
    5 - 10L water

    I you don't have a sprayer for the sugar, use a soft broom to apply.

  6. #6
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    The times I have seen exposed ag laid they use a roller to flatten the stones down several times, after washing off.

  7. #7
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    Might be a Sydney thing achjimmy, i've never seen that in QLD. If it's screeded properly, floated then trowelled, there shouldn't be a need. Once it's hosed off up here, the concrete underneath is pretty much off. Can't imagine a roller making any difference.

    Another thing to note, about a week after, acid wash then apply a sealer.

  8. #8
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    Any of the concrete sites I've looked at say NOT to use suger but to use the acid?

  9. #9
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    without using a retarder it's not going to come up very well. I guess the concrete companies are just covering their butts by saying they won't cover any defects if a retarder was used.

  10. #10
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    I take it your not worried about matching new to old.....

    its hard enough to match 2 mixes poured on 2 separate days.

    use retarder, it guarantees a more controlled exposure, and you can wash it off the next day with a pressure washer at a 30-45 degree angle. Don't go straight down you might remove too much stone. Do it roughly first then detail after. This ensures it doesn't cure before you get all of it. You can do it same day with a hose and broom but this is not my preferred option.

    Final was with copious amounts of water to flush the last of the slurry, then seal when dry. After that you cut your control joints, wash and final seal.

    thats how I do it in melbourne.

    good luck!

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