The Well-Planned Driveway

1. The 18-year-old concrete drive, riddled with cracks, is broken up with a hydraulic jackhammer and hauled away. Concrete and asphalt can be pulverized and reused as roadbed, the gravelly base for pavement.

2. The ground is leveled and firmed with a "jumping jack" compactor. Whether the driveway is concrete, stone, brick or asphalt, the ground beneath must be flat and stable for good results. If you've got clay or other problematic types of soil, consult with a civil engineer.

3. Forms made from 1x6 boards are staked into place to shape and hold the concrete. These will be removed after it sets up.

4. A four-inch layer of roadbed is poured, leveled and compacted once again. This creates a firm base for the concrete. The roadbed also helps insulate the pavement from freeze/thaw movement in the ground below. In some parts of the country, where the soil is sandy or filled with clay, roadbed may be laid as thick as 12 inches. The soil here, just west of Denver, is relatively stable.

5. To add strength, wire-reinforcing mesh (10 gauge) is spread over the drive. It will be lifted into the concrete as the slab is poured. You can forgo the mesh by specifying a concrete mix that is fortified with plastic fiber. If the soil base is poor, steel-reinforcing rods (rebar) can be used to strengthen the slab.

6. Concrete is poured to a depth of four to six inches, depending upon how much traffic the driveway will carry. In some communities, codes dictate how thick the driveway slab, as well as the roadbed, must be. Check with your building department. As a rule, the thicker the concrete, the stronger the driveway.

7. A screed (in this case, an aluminum bar with handles) is used to distribute and level the concrete. The surface is then worked with a float, which resembles a trowel, to make it smooth and to release any excess water that has risen to the top of the pour. Installers must be careful not to overwork the concrete, as releasing or bleeding too much water leaves a chalky surface and compromises the strength of the slab.

8. Using a 2x4 as a guide, control joints are cut with a jointer, which resembles a trowel with a blade in the center. At this point the concrete is firm enough to support some weight but still wet enough to be worked. The joints, which divide the drive into six-by-eight-foot squares, give the concrete a place to expand and contract. The idea here is that the concrete will crack along the joints and not in the middle of the slab. If cracks do form elsewhere (usually due to shifting soil or an inadequate base), they must be patched to prevent water from working its way into the concrete and spalling it.

9. A chemical retarder that has sugar as a primary ingredient is sprayed on the surface to slow the setting time. The retarder penetrates only the top 1/16-inch, allowing the concrete underneath to set at its normal rate.

10. A film of plastic is laid on the driveway to keep the retarder from evaporating and to protect it in case of rain.

11. Two to 12 hours after the retarder is applied, the plastic is peeled back and the driveway is hosed down with water. Fine cement particles and sand are washed from the surface, exposing the aggregate beneath. Then a muriatic acid solution is applied to clean the stone. The next day, an acrylic sealer is sprayed on to protect the surface from staining and weathering. The sealer also makes the surface appear damp, bringing out the colors of the aggregate. For best results, the sealer, which is available at home centers, should be reapplied every two to five years, depending on weather conditions. In about ten days, the driveway is firm enough for traffic.