OUR PATIO STONES

On the Master Gardeners' tour last spring there was quite a lot of interest in our paving stones. We made all the pavers in our vegetable garden, English garden and Spanish oak garden. Although I had planned to do a post on the "how to" it was not until Central Texas Gardener asked me this week if I had ever done a post on the stones that I actually got round to it.

The pavers in the vegetable garden were made using the above frame, the English garden using the round form and the larger pavers in the Spanish Oak garden were poured in place.

D has provide me with the following.

"First a disclaimer. If you can find the right size and pattern of stepping stone at Home Depot or Lowe's, buy don't make. We could not find an 18" square stone, so we decided to make. We already had a concrete mixer so we were not faced with an initial capital outlay of about $400 to get started. We used the standard concrete formulation: 3 parts gravel, 2 parts masonry sand and one part portland cement. If your project is modest you may want to use concrete premix; our project warranted bulk purchase of the ingredients. For enough to make three 18" square stones (2" thick), we mixed 6 shovels of pea gravel, 4 shovels of masonry sand, 2 shovels of portland cement. To vary the color of the stones we used gray cement and white cement in varying proportions and concrete pigment in varying amounts. We cannot offer precise color formulations; it was very much "trial and error". Since we made almost two hundred stones, we had plenty of scope for color variations; the more the better. We found the best order of mixing to be: water first, gravel next and then sand. As the mix dried out with the addition of sand, we added more water for desired consistency. Experience will guide you on the initial charge of water; I cannot remember. Our technique was quite tolerant of varying consistency of the mix but too thin made for a slow set and a weaker stone; we suffered no broken stones. 

We started with a single mould, increased to a double and ended with a treble. The key to building the mould is screw, don't nail, the sides together. We used 1 7/8 X 3/4 inch wood for the frame and 3 1/2 inch screws to assemble it. The easiest way to release the stones from the mould was by unscrewing the sides and dismantling the mould. We reused the same triple mould about fifty times. We laid the mould on a level bed of sand; it’s important to level the mould. Just prior to pouring the concrete we sprayed WD40 on the inside surfaces for easy release. We emptied the mix into a wheelbarrow and from there we transferred it into the moulds by shovel and garden trowel. We filled each mould half full, leveled it, and laid a pre-cut heavy gauge 2” mesh screen (16” square) onto the concrete as “rebar”. Then we filled the mould to the top. We dragged a 2 X 4 across the surface of the mould to remove excess concrete and form a level stone. Then we inserted a flat 2 inch trowel down the inside surfaces and worked it around the mould to "finish" the sides of the stone. Now came the most important step. When the surface water had disappeared, typically 20-30 minutes, we "finished" the surface to a smooth sheen with a 11 X 4 1/2 inch trowel. Finally, when the surface was firm, we used flat rocks to imprint a pattern on the stone. We then left the stones to cure for 24 hours.

For the large diameter circular stones we used black plastic planters. We filled the planter to within 3” of the top with sand and then followed the same procedure to form the stones. We upended the planters onto a thick cushion to release the stone from the mould; the larger mould was quite a challenge."

It all took a lot of time and effort! Thanks D for a great job.