There are some important basics to know about how to pour a concrete driveway. This task is more than just excavating the driveway and pouring concrete into the area. The following will explain what to do before, during, and after the concrete pour.
Insert steel pins to define the dimensions of the driveway.
Shoot elevations with a builders level or transit.
Mark the elevations on the steel pins.
Tie a string line to the elevation marks.
Using steel forms or forms made from lumber, set the forms to the height of the string lines.
Excavate the area with a backhoe or skid steer to achieve the proper thickness. Residential driveways are generally 4” thick.
Once the grading is completed, use a gasoline powered tamper to tamp or compact the area to be poured.
Fill the area with 2” of either #304 or #57 gravel. These are the most common aggregate used as a sub base for all driveways.
Cut enough ten gauge wire to cover the entire area to be poured. Make sure the wire overlaps by 6”.
The concrete for residential driveways is a six sack limestone blend with air at 4000 PSI. The concrete batch plant creates air in the concrete by adding a chemical to the concrete. This air allows the concrete to endure cold weather better. 4000 is the strength of the concrete, and PSI means pounds per square inch.
Concrete should be ordered from the batch plant the day before it is needed.
On the day of the pour, concrete rakes are first used to get the elevations close. Then a straight edge is used to reach the exact elevation.
After straight edging, a bull float is used to close up the top of the concrete. This brings the concrete to the surface and takes the gravel down.
The surface of the concrete should then be finished with a fresno or hand float and trowel while the person is on kneeboards.
An edging tool with a ½” radius is used along the sides of the driveway to eliminate any sharp edges.
The final, non-slip finish is achieved by making figure eights or swirling motions with a hand float. Uniform, straight passes are made with a finishing broom.
A curing and sealing compound should then be sprayed on the new concrete.
The Day After the Pour
Stress cuts should be made with a concrete saw. 4” slabs should be cut at least 1½” deep. Blocks should not be any larger than 8 ft. squares.
In the spring and fall, vehicles should not be driven on the new concrete for ten days. Waiting seven days in the summer months is acceptable since concrete cures faster.
The new driveway can be walked on the next day at any time of the year.
Concrete sets faster in hot weather so it is important to keep on top of it before it gets
too hard. Dampening the base with water from an outside hose slows down the setting time.
Concrete takes longer to set in cold weather. Calcium chloride can be added to the concrete to speed up the setting time.
Concrete should not be poured if the temperature is below 32 degrees or if the ground is frozen. The reason is that the elevation drops during thawing and may cause the new concrete to break.
Using salt on a concrete driveway in the winter to melt ice will pit the concrete. It is recommended to use clean sand for traction instead.
Knowing all the aspects of how to pour a concrete driveway are important. This task requires a team effort of rakers, straight edgers, and finishers. Enough people are needed on site to properly perform all the steps in a timely manner to achieve a beautiful driveway.
This article is a guest post from a cement finisher with 30 years of experience and owns his own concrete company.