Replies

1. 
   Guest_ | Jun 22, 2000 07:06am | #1

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   Hire a pro who regularly does aggregate flat work, and don't espect a perfect match. The results will depend upon a number of factors extending from who mixed what at the plant on a given day to the curing/washing process used as the project nears completion. You can help by cleaning (i.e., power washing w/some bleach) the adjacent surfaces before getting an estimate... this will assist in determining the material and finish for the repair work.

   Good luck, Steve

1. 
   Guest_ | Jun 23, 2000 02:36am | #2

   *Rich,This is for pro's only. Don't try this yourself unless you've done it for years or are prepared to tear it back out and hire a pro.Ed. Williams

2. 
   ROGER_CUTRUFELLO | Jun 23, 2000 05:23am | #3

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   CAN ANYONE EXPLAIN THE PROCESS.

3. 
   Guest_ | Jun 23, 2000 06:35am | #4

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   Well, I was going to type an explanation, but being lazy, I mean smart, here's an excerpt form a 10/96 JLC article by Dennis Golden:

   b EXPOSED AGGREGATE

   An exposed aggregate finish has a lot
   going for it. The uniformly exposed stone
   surface is attractive, the finish is relative-ly
   easy to produce, and the cost is often
   comparable to that of a standard slab.

   b The Mix
   The appearance of an exposed aggre-gate
   slab depends entirely on the stone
   chosen for the concrete mix. Different
   concrete producers get their stones
   from different sources, and the varia-
   tion in color can be significant. The size
   of the stones will also affect the finished
   appearance - the larger the stones, the
   coarser the texture. Most concrete pro-ducers
   offer aggregate in sizes from 3 /8 to
   1 1 /2 inches, and an exposed aggregate
   mix typically has 5% to 10% more
   stone than a standard mix.
   Before agreeing to provide an exposed
   aggregate finish, you should discuss the
   appearance of the aggregate with your
   clients, and note any preferences they
   may have. If it's important that their
   slab looks like the one next door or
   matches existing work, make sure you
   know the size and source of the stone.

   b Seeding Is an Option
   An alternative to using the "straight"
   mix from the local concrete company is
   to augment the mix with stones of your
   own choosing. If your customer wants a
   particular type or size of stone incorpo-rated
   in the finish, they can be "seeded"
   into the concrete surface. The stones
   are tossed out on the freshly poured
   slab, floated into the surface, and then
   re-exposed when the concrete starts to
   set. Seeding is a tricky procedure and
   requires a finisher with a good eye as
   well as a steady arm.

   b Timing Is Everything
   An exposed aggregate slab is poured
   and floated in the same manner as stan-dard
   slab. After the final floating, the
   procedures change. Using an ordinary
   spray can, a retarder is sprayed evenly
   over the entire surface, the same way a
   curing compound is sprayed. This slows
   the set at the surface of the slab. A sugar
   water solution of 4 ounces of sugar for
   every gallon of water makes an accept-able
   retarder.
   The concrete below the surface is
   unaffected by the retarder and sets at a
   normal pace. When it's time to wash
   away the surface cement and expose the
   aggregate, the firmer concrete below
   will hold its own against the water spray.
   The slab is ripe for exposure when a
   16-penny nail will no longer penetrate
   the surface (apply the same pressure as
   when writing with a pencil).
   Exposing the aggregate is a two-per-son
   operation. Starting at the high side
   of the slab, a hose set to a fine spray is
   held a few feet off the slab, and the sur-face
   layer of cement is washed away. A
   second person gently brooms back the
   sand and cement that accumulates in
   front of the spray (Figure 5).

   b A Sealer Enhances Appearance
   It's a good idea to apply an acrylic
   sealer to an exposed aggregate finish.
   The sealer will enhance the appearance
   of the exposed stones (it creates a "wet"
   look), and prevent the slab from absorb-ing
   moisture (important in frost-prone
   climates). The sealer, available from
   W.R. Meadows (P.O. Box 543, Elgin, IL
   6012; 800/342-5976), costs between
   $16 and $20 per gallon and can be
   applied with a hand sprayer. Coverage is
   approximately 200 square feet per gal-lon.
   The sealer should be reapplied
   every year.

   b Plan for Runoff
   Runoff water from an exposed slab
   project is nasty stuff. When handled
   improperly, the diluted cement paste
   can "burn" vegetation, instantly discol-or
   a blacktop driveway, and get you in
   big trouble with the downhill neigh-bors.
   If necessary, the wash water can be
   contained with dirt or sand dams, and
   the mess can be mucked into a wheel-barrow
   for on-site or off-site disposal.
   Just be sure you have the necessary
   materials on hand before the pour.

4. 
   Rich_Grigoli | Jun 23, 2000 06:36am | #5

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   I have to repair two sections on an exposed aggregate sidewalk. I would appreciate input from anybody that has any experience with this style concrete work. Thanks all.