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This article will guide you through the process of buying a quality concrete driveway that will enhance your home’s value and provide years of low-maintenance service.
Before you start calling contractors, do a little homework. For most homes the location of the driveway is obvious, but be sure to consider factors such as adequate width, turning areas, tying in to existing sidewalks, and whether or not the driveway might do double duty as a basketball court or play area. It will generally be easier and less expensive overall to complete your project all at once, rather than in stages, so be sure to anticipate future needs such as a second (or third) vehicle, and room for parking a travel trailer or boat. Keep in mind that it will be nearly impossible to match the color of an existing driveway if you decide to add an additional area down the road.
Make sure that the ground where the driveway is to be constructed offers uniform support. With new homes, there may be a foot or more of freshly placed dirt underneath the driveway area, especially near the garage entrance. If this dirt was not properly compacted during placement, it could settle several inches in the next few years. Any driveway built on uncompacted fill will sink as the ground compacts itself, leaving you with an expensive problem. Be aware of potential settlement around culverts, pipes and other structures and make sure the driveway provides proper drainage away from your house or garage. Also be sure that your planned driveway does not cover up access to important utilities, pipes, or your septic tank.
Most importantly, clarify your expectations about your new driveway, and make a list of your top five concerns to share with all potential contractors. If your biggest concern is random cracking, slip-resistance, or drainage tell your contractor up front.
Most problems that are objectionable to homeowners are directly related to the workmanship employed in constructing the driveway: random cracking, surface blemishes, insufficient thickness, and poor detailing are all controlled by the installer. Selecting a quality-conscious contractor is your best assurance of getting a quality driveway, but how do you go about finding that contractor?
The yellow pages may be one place to start your search, but don’t neglect references from friends, your builder, or local ready mix concrete suppliers. However you come up with your list of contractors, be sure to ask them some important questions. Find out how long they have been in business, ask for references, and see if they offer any kind of warranty on their work. Ask for the location of work they have completed recently, as well as some projects from 3-5 years ago. Check out these projects, and determine whether or not the workmanship exhibited in these projects is what you expect, and see if the quality has endured in the older projects. Be sure to share your top five expectations with all potential contractors – they need this information to prepare a realistic proposal and quotation, and you need express your expectations before the job begins, not after it is completed. Be sure to get a written proposal and not just a price quotation.
Find out what kind of concrete mix the contractor normally uses. Don’t be talked into a cheaper concrete mix that will cost you money for years. Repairing problems caused by a cheap mix can be more expensive than the original cost for installing a driveway, while the additional cost of a high performance concrete mix is only pennies per square foot. Ask the contractor to quote his normal driveway mix and a high-performance concrete mix to test the difference.
Here are Ten Tips for buying a concrete driveway for your home:

• Use a high performance, air-entrained concrete mix.

The concrete should be at least 3000 psi, with 4% air-entrainment. High-performance concrete will include fly ash and water-reducing admixtures to provide long-term strength gain and initial workability without the addition of water. High-performance concrete mixes can be designed for easy placement, so your contractor isn’t saddled with a hard-to-handle concrete mix.

• Install joints at a spacing of no more than 10′ x 10′.

Spacing joints at wider intervals invites random cracking. While such cracks are generally not a structural problem, and will not reduce the service life of the driveway, they are unsightly. Also avoid joint patterns that produce rectangular or triangular sections. Concrete likes to be square, so lay out your joints to form square sections. If in doubt, make the sections smaller, not larger.

• Form the ’street edge’ of the driveway, leaving it 1 or 2 inches above the street.

This formed lip will provide a visually clean line for the end of your driveway. Make sure the concrete is at least 6 inches thick next to the street or end of your driveway. This area of the driveway takes lots of abuse as cars enter and exit the driveway.

• Thicken the edges of the driveway by 1 or 2 inches.

This provides additional structural support in the area most likely to be subject to heavy loading. All edges should be thickened if possible, with the thickened section extending in from the edge of the slab by 4-8 inches. The extra amount of concrete is very small, and the long-term benefits to the driveway are substantial.

• Use a minimum thickness of 4 inches of concrete.

Keep in mind that the 2 x 4’s often used to form driveways are only 3 ½ inches wide, so the ground inside the 2 x 4 forming needs to be removed at least ½ inch below the bottom of the form. Thickness is the major factor (even more than the strength of the concrete) in determining the driveway’s structural capacity. Increasing your driveway’s thickness from 4 inches to 5 inches will add 20% to your concrete cost, but the additional inch of concrete will add almost 50% to load-carrying capacity of your driveway. Keep in mind though, that if cushion sand is being used inside the form boards, that sand will be compacted by the weight of the concrete by 1/2” to an inch, making the concrete thicker.

• Use only a broom or other textured finish (no steel troweling).

A textured finish is desirable for traction and safety. Over-finishing the concrete increases the possibility of surface problems such as scaling and de-lamination. The concrete should be poured, leveled, then Bull-floated to ensure a uniform surface. Towards the end the edges will be rounded and the surface sealed with a trowel. Now a broom is used to texture the surface. No other finishing is necessary in most cases.

• Let the concrete dry and use quality sealer on your new driveway.

Curing of the concrete is a process, and one of the most important. Unfortunately, it is also one of the most neglected. In extreme cases, failure to cure concrete can result in reductions of strength up to 50%. Failure to let concrete cure always reduces the strength and resistance to the effects of weather. We recommend not having any heavy traffic on your new concrete for at least 7 days. After that the concrete dried enough and is ready for normal traffic. Still it takes about 21 days for concrete to dry out to the point it needs to be. At that point concrete can be sealed with a sprayer or a paint roller, and dries in one to two hours. Make sure the product lets moisture thru, but seales against stains.

 

• Don’t use salt to remove ice the first winter (sand works well).

Avoid the use of salt on your driveway if possible, but especially in the driveway’s first winter. This is especially important if your drive was built in the fall of the year, as ‘young’ concrete is generally more susceptible to the potential harmful effects of salt.

• Never use products containing ammonium nitrates to de-ice your driveway

(If the label does not tell you the active ingredients, don’t use the product) Ammonium nitrates and similar products don’t just increase the possibility of surface problems for your driveway, they actually attack the concrete. Be careful of spilling fertilizer products on your drive, as many of these contain chemicals that will attack your concrete.