How to Pour a Circular Concrete Pad

Drive a large stake into the center of the work area with a hand sledgehammer. This stake must be at least elbow height and firm enough to use as an anchor. Measure and cut a length of rope equaling the radius of your proposed circular concrete pad using a knife and a tape measure.

Screw a large paintbrush onto the end of a rolling pole, and then tie that pole to the stake through the eye-hole in the bottom. Dunk the brush in a paint can, pull the line taut and walk around the circumference of the circle. If you keep the line taut and the pole straight, you eventually paint a circle in the grass around the stake, marking the perimeter of your circular pad.

Drive more stakes with the hand sledgehammer, marking the outside of the perimeter at 2-foot intervals. Excavate the circular area by digging out the sod and dirt to a depth of 11 inches. If you intend to build a large concrete pad, use a backhoe in place of a shovel.

Install 2-by-12 form boards around the inside of the excavated area to create the mold. These boards are flexible, so bend them to match the outside edge and fasten them to the stakes with penny nails and a claw hammer. Wherever the form boards meet, drive a new stake and nail the form boards to that. Add extra stakes wherever it is necessary to reinforce the curvature of the boards.

Fashion a set of 2-foot sections of steel rebar with a rebar cutter/bender, and drive these stakes around the interior of the perimeter of the pad. The stakes must be set 6 inches back from the perimeter, placed at intervals of 6 feet, and 8 inches of the rebar must remain above the surface of the ground. These steel stakes provide a frame for a reinforcing grid of steel rebar.

Dump loads of gravel from a wheelbarrow and fill the bottom of the mold. Use an iron rake to spread the gravel, and compact it with a dirt tamper or power compacter. Continue dumping, spreading and compacting until you have a flat, 6-inch-deep layer of gravel.

Measure the distance between the steel stakes on opposite sides of the circle with a tape measure, and cut sections of rebar to match those measurements. Bridge the steel stakes by laying the rebar across the right-to-left axis (or X axis) of the circle, and then tie the rebar onto the stakes with wire ties and either pliers or a wire-tie tool, elevating them 3 inches above the gravel. Repeat the process for top-to-bottom axis (Y axis) to create a grid pattern.

Mix concrete in the wheelbarrow and dump it into the mold. Instruct an assistant to spread the concrete with an iron rake as you continue to mix and dump more concrete into the mold, filling it up to the rim. For a large job, arrange to have a truck delivery and pour your concrete.

Flatten the surface of the concrete by scraping a piece of scrap timber, such as a 2-by-4, across the top, using the timber as if it were a squeegee. Finish and smooth the surface with a bull float, raising the forward edge of the float slightly so as to avoid plowing the wet concrete. Draw an edging float around the sides of the circle if you want the pad to have rounded edges.

Watch the concrete pad's surface over the next two to three hours, so as to note when water pools on the surface and is then reabsorbed. After the water is reabsorbed, finish and smooth the concrete with a magnesium float.

Check the progress of the concrete after one or two hours by pressing it with your finger. When the concrete is hard enough to resist your pressure, but still wet enough to develop an imprint, cut a pattern of expansion grooves into the pad. Lay out a piece of scrap plywood planking to kneel on, so as to spread your weight across a larger surface area and avoid making impressions, and carve the grooves into the surface of the concrete by drawing a grooving tool across it. The expansion groove pattern is up to your discretion and the size of the pad, but as a rule you need an expansion line for every 10 square feet of concrete surface.

Allow the concrete to harden overnight before breaking down the stakes and form boards of the mold. Removing the mold will leave a thin trench around the exterior of the pad, so fill this in with leftover dirt.