How would you like to pave a patio, driveway or basketball court for about 10 cents a square foot? You can if you use soil cement.
Never heard of the stuff? Well, it's nothing more than plain, ordinary dirt mixed with cement. It's not as strong as concrete, but it's a whole lot cheaper. And it is strong enough for most purposes as long as you have the right kind of soil.
Best is sandy, gravelly soil generally found to the east of Washington; you can get away with a 10 per cent cement mixture. With the kind of subsoil in other parts of this area you need more cements, about a 12 per cent mixture. If your soil is almost pure clay, as in a few of the red dirt zones, forget about soil cement; clay requires lots of cement and it's the devil to mix properly.
Start by removing the sod and topsoil over the area you want to pave.
How much cement you'll need for the job depends on how deep you're going to pave - four inches for patios and walks, five inches for driveways, six inches for driveways that bear trucks. Mark off the area to be pave into a grid, with each square representing the area each bag of cement will cover: 30 square feet for four inches deep, 24 square feet for five inches deep, 20 for six (smaller if your soil is clayey or loamy). Place a bag in the center of each square. Break the bag open and rake its contents out evenly over the surface of its square.
When all bags of cement are spread, go over the whole area with a roto-tiller. To assure an even distribution of cement, till the area first in one direction, then again at right angles to the first series of passes. Keep at it until everything is well mixed. Use a shovel to dig a few test holes to make sure you are mixing to the proper depth.
When you are satisfied that your area is well mixed, spray it as evenly as possible with a garden hose. Till again, mixing the water into the blend. Add only enough water to make the mix plastic.
Now rake the area as smooth and level as possible. Tamping comes next. Screw a square-foot piece of plywood onto the end of a four-foot four-by-four. Use this tool to smooth and pack the surface.
Once the soil-cement has been tamped, scratch it up with a rake. Grade the loosened surface material with a board, scraping off the high spots and filling the low spots. Spray again very lightly with a fine mist, then tamp again.
For an even smoother surface, run a lawn roller over the soil cement. Make a series of perpendicular passes for the smoothest finish. But don't expect a finish like you'd get with real concrete; you just can't get it with this technique.
For the next several days, keep the soil cement moist. Remember, cement products harden by a chemical setting action, not by drying. And that chemical reaction can take place only in the presence of water. If you let the slab dry out it will lose strength.
So sprinkle the slab very lightly with a fine mist the first day. After that you can hose it down heavily without damage. In time your work will probably begin to develop tiny shrinkage cracks. Don't let them bother you, they are normal and won't affect the life of the slab. Soil-cement highways have held up for 40 years.