Replies

1. 
   Gene_Davis | Dec 01, 2006 04:36am | #1

   Here is what works for me.

   First, make three little 12 x 12 forms with 2x4s.  These will be used to make your "set-up time test pads."

   Make or order your mix with the appropriate gravel aggregate, so as to best match what you are trying to do.

   Place, screed, and float per your usual practice, doing the three little pads at the same time as the main piece of work.

   Using a garden sprayer, and a mix of sugar or molasses and water, spray the surface of the freshly floated work, including the test pads.  I use about 6 oz. of molasses or 4 dry oz. of granulated sugar per 1.5 g. 

   Sugar is a retardant, and will keep the surface fresher than the underlying crete mix, which is what you want for this.

   Now, wait until the crete starts to cure and harden, just like the wait you would do if doing a smooth trowel job.

   Using a garden hose and a fine spray under good pressure, test to see on pad #1 whether the surface has set enough to be able to hose away the cream but leave the exposed aggregate well-bedded.  Too soon and you will wash away too much.  The work will be set up firmly at this point, certainly firm enough to walk on it.  I recall doing first tests at maybe 40 minutes after float-off.

   If too soon, wait a while and do test pad #2.  Maybe you will even need pad #3.

   Once you have begun on the main piece of work, keep spraying so as to work the cream off to the edges and over form edges to get the work surface all uniformly washed.  The spray-off takes a little work and time.  Relax, you'll get it right, and will be pleased with the result.

   The first time I did one, the batch plant had no washed and smooth pea gravel, only having crushed granite, which had sharp contours and edges.  I got a few 5 g. buckets of what I needed at a landscape supply place, and seeded the surface of the work with it, after screeding and before floating.  It came out well.

1. 
   brownbagg | Dec 01, 2006 06:11am | #2

   yes, what you said.

2. 
   dovetail97128 | Dec 01, 2006 06:36am | #3

   I will make several assumptions here. First: at 1/3 yard you are going to either mix your own mud or use a "U-carry" trailer mixer. Second: you have poured flat work before.
   Matching the aggregate will be tricky unless you "seed " the top. Appropriate rock can be found in most garden/landscape supply yards that carry landscape rock.
   As for the pour itself, screed it as flat as you possibly can right off the bat. The one thing about exposed is that if you leave ridges, or any impressions in the surface they will show up in the final product.You want to place the mud as uniformly as possible, any real differances in the consistency will show up after the wash down. This includes the shovel full thown in to fill a low spot and then troweled into place. You want to work the surface as uniformly as possible but also as little as needed.( I once left a perfect impression of a knee board in an exposed slab that never showed up until we washed the slab off! I had knelt on the knee board on the wet mud prior to bull floating and trowelling it all flat. The surface had finished flat but when using the board I had pushed the aggregate down and it showed.)
   You should be able to contact a masonry supplier or concrete batch plant in your area that can guide you to a commercial product that "kills" the surface of the concrete, does same thing as the sugar mentioned earlier but much more reliable and consistent. It also doesn't require guess work about how long until you wash off.
   I don't know of any names off the cuff, but do know it is out there as my flat work guy and I just had a discussion about much easier and reliable it was over the old sugar water way. Last, be careful with the wash , it is pretty easy to be too aggresive and blast aggregate out of it's setting.

3. 
   Hackinatit | Dec 01, 2006 01:48pm | #4

   You can make the aggregate match following the previous processes, But...

   You'll have no control over the sand/cement color. In my experience, the sand/cement in the new 'crete will show differently than  the old. The old aggregate has had years to collect dirt/leaf stains/bird poo/kids' chalk/etc.

   I think the best you can do is make sure you spray the finished product with acid and wash off. It will begin to match better as it ages and "gets dirty".

   This pad has ALMOST the same appearance as the old after 18 months. I don't have a current pic, but you can see how different the two were when new.

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   Troy Sprout

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   Edited 12/1/2006 5:50 am by Hackinatit