Determine specifications. Driveways for one-car garages should be at least 10 feet wide. A two-car driveway should be 16 to 24 feet. The slab's thickness depends on the vehicles that will roll on it. A good measure is at least four inches for cars and at least six inches for heavy trucks. If the soil is soft or drainage is poor, add another one or two inches.
Design the slabs. For six-inch slabs, use a shovel to dig at least eight inches deep to accommodate for a four-inch gravel bed and raising the slab two inches above the grade. To prevent water from flowing into a garage, the slabs butting against the garage floor should be about one inch below that of the garage floor. For a six-inch slab, use 2 x 6 wood borders to create the forms.
Slope away the rain. The land should slope gently from garage to street, at least one-quarter inch per foot. A rise greater than one and three-quarter inches per foot will cause most cars to scrape the rear bumper on the driveway. If the slope is reversed, from street to garage, install a drain and drainage channel where the driveway meets the garage to divert water.
Build the slabs. Pour the concrete, smooth it with a wood float and cut the isolation joint with a trowel. Set isolation joints where the drive meets the garage, walkways and the street. Control joints should be no more than 10 feet apart. A longitudinal control joint should be included down the middle of the driveway. Cut control joints at least one-quarter of slab depth.
Curve entryways. To create a curved apron from sidewalk to street, set stakes at the edge of the sidewalk, about 15 feet from either side of the driveway. Hammer a nail into the top of each stake and attach a 15-foot string to the nail. Use the string as a radius to place additional stakes in the desired curved pattern. Dig 10 inches deep between the curves and extend the excavation nine inches beyond the stakes. Build slab forms with 2 x 2 boards, lay the gravel base, pour the concrete, smooth it and install isolation joints.