How thick should cement drives be?

Concrete drives are a popular option because they are quite versatile and offer the owner a long lasting durable drive. There are several issues to keep in mind when selecting and pouring concrete for a drive, most notably the thickness, specifications and curing of the concrete itself.

Concrete dimensions

A successful and long lasting drive requires adequate specifications and dimensions. First, the drive should be about 2.4 to 2.7 m (8 to 9 feet) in width to accommodate two cars. The length depends on how far back your house is set. If you would like to double the width, plan for about 4.5 to 5,4 m (15 to 18 feet). You can plan to have the entryway of your drive be a single car width and widen as the drive approaches the house.

The base of the drive should be either soil or gravel; if it is gravel, make sure to compact the gravel to create a smooth surface. The depth or thickness of the concrete should be about 10 cm (4 inches) for a standard drive (passenger cars) and about 12.5 cm (5 inches) for heavier vehicles. This thickness should be consistent throughout the drive. Also, create a sloped grade toward the street of about 1 per cent or 3 mm per 30 cm (1/8 inch per foot).

Using quality concrete

The thickness and dimensions of the concrete are just as important as the type of concrete that you use. Concrete is specified in accordance with the American Standards for Testing and Materials (ASTM). You should select concrete with an ASTM C-94 rating. Your concrete should have the following specifications:

Compressive Strength: 27, 579 kpa (4000 psi) at 28 days Air Content: 5 to 7 per cent Slump: Request 10 cm (4 inches) of slump. Avoid anything greater than 12.5 cm (5 inches). Aggregates: You want a coarse aggregate of 1.8 or 2.5 cm (3/4 to 1 inch).

Requesting these specifications will prevent the concrete from cracking and provide the most strength given your concrete drive's thickness.

Curing the concrete to prevent cracking

Now that you have the appropriate dimensions and specifications and have properly laid your concrete, you will need to maintain it to prevent cracking and allow for proper curing. Once you lay the concrete and have smoothed it to a level, smooth surface, you will want to use form oil on the surface and moisten the surface with water. Additionally, the concrete must "cure" or dry properly to prevent cracking. You can use a curing solution or you can continuously wet the concrete. Make sure to not over water the concrete, causing puddles on the surface. Curing should last three to seven days.

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About the Author

Graham Beckett is an attorney in Los Angeles who has practiced in California since 2006, providing thoughtful analysis and writing on various legal issues. Additionally, he is an avid surfer, runner, and comedy writer, writing and performing in various sketch shows throughout Los Angeles.