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tom1st 07-08-2006 04:38 PM

stone veneer formula
Anybody know of a proven formula for lightweight stone veneer for a diy project/

redline 07-08-2006 04:48 PM

Mixing Concrete:

1. You can buy pre-mixed bags of ready-to-mix concrete. These simply require water and mixing; the measuring is already done for you. An 80 lb bag will, on average, will make 4 sq. feet x 2.5" thick. A more economical method is to make your own concrete, using this simple time-tested formula as a guide - 1:2:3 parts by dry volume - one part Portland cement, two parts sand three parts coarse aggregate. For molds under 2" in thickness, use aggregate that is no more that 1/4" in size. Concrete can take anywhere from 15min to 24hrs to set it all depends on what concrete mix is used, weather conditions, the size of the mold, and the amount of water used, the cycle time can be reduced further by using only enough water in the mix as is absolutely needed, or using a faster setting concrete mix, professional concrete casting company's will use a small of amount of water, between 5 to 15 percent, this will aid in hardening the mix as fast as possible.

2. A light weight concrete mix can be used for a wall veneer stone, or patio applications to make light weight concrete, substitute some of the aggregate with pumas stone , styro-foam beads or perlite - even wood chips.

3. Coloring and texture can be done several ways, there are many types of powders and liquid color additives available; you can even purchase colored concrete. For the look of real stone, color the concrete first then use one, or two different colors of the powder type sprinkled and smudged around in the mold before pouring in the concrete, this will give a very random look from one stone to the next, also there are many types of concrete stains that can be applied to the finished stone, if you prefer a rougher texture to the finish stone, sprinkle a small amount of baking soda in the mold before pouring.

4. Using a shovel mix these ingredients into a wheelbarrow or onto large tarp or bucket, It is wise to start with a moderate amount of dry mix as it gets exponentially harder to mix as water is added. Be sure it is evenly and completely mixed. Use the minimum amount of water possible while still keeping the mixture workable. The less water used, the stronger the dried, finished product will be, and will cure faster.

5. Try to use the same amount of water for additional batches to be mixed, and work fast to keep dry lines from forming. This is where the concrete is already drying and the transition to the new, wetter mix will be clearly visible and create a weak point.

Pouring Concrete:

Using a mold release agent is not required for some molds, but using some sort of mold release spray wax or caster oil will help to release deeper castings .

1. , After pouring, shaking side to side and tapping the sides will draw most air and water away from the surface of the mold helping to avoid surface voids. and air bubbles.

2. During pouring, the molds do not require backing - though it is recommend that, to achieve the best results when pouring molds over 3" thick, they be packed into sand for support.

3. When only half or a partial part is required, simply insert a divider wall into the wet mix. this will enable you to make any shape without breaking the finished stone after it is already cured, this is extremely helpful for veneers if you need a special shape to fill a gap.

Releasing Castings:

1. Concrete can take anywhere from 15min to 24hrs to set it all depends on what concrete mix is used, weather conditions, and the size of the mold. After release additional drying can be done out of the molds, the cycle time can be reduced further by using only enough water in the mix as absolutely needed, or using a faster setting concrete mix

2. Molds are made from a polyethylene material, a flexible type of plastic that allows the concrete castings to be released quite easily - you may find deeper castings may require a little more effort, if a mold release is needed you can simply smear a very small amount of motor or castor oil in a clean mold before pouring.

3. Make sure that the concrete has dried and hardened before you release it from the mold; concrete will shrink slightly, during the hardening process, and will be easier to remove.

4. Clean the mold with water, after each use.

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