Which statement describes the recommended spacing for control joints in driveways?

Which statement describes the recommended spacing for control joints in driveways?

• A. Exactly 20 feet on center.
• B. Spacing equal to the slab width.
• C. At a distance equal to the width of the slab.
• D. No joints are required.

Answer: (B)

Control joints are placed to guide where cracks will form as concrete shrinks and temperature changes, so cracks stay in predictable lines rather than randomly across the surface. The best spacing is about the width of the slab, which makes the panels roughly square and helps keep cracks from running long distances. This approach reduces unsightly cracking and makes maintenance easier. A fixed distance like 20 feet doesn’t adapt to different driveway widths, and having no joints at all leads to uncontrolled cracking. So, spacing the joints equal to the slab width best achieves the desired result. For example, if the driveway is 8 feet wide, place joints about every 8 feet along the length.

Control joints are placed to guide where cracks will form as concrete shrinks and temperature changes, so cracks stay in predictable lines rather than randomly across the surface. The best spacing is about the width of the slab, which makes the panels roughly square and helps keep cracks from running long distances. This approach reduces unsightly cracking and makes maintenance easier. A fixed distance like 20 feet doesn’t adapt to different driveway widths, and having no joints at all leads to uncontrolled cracking. So, spacing the joints equal to the slab width best achieves the desired result. For example, if the driveway is 8 feet wide, place joints about every 8 feet along the length.