Which of the following is NOT an element of laying a concrete slab on grade?

Laying a concrete slab on grade involves several key elements that contribute to its stability and durability, and recognizing what is not necessary can clarify your understanding of construction practices.

In this context, while it is essential to ensure a concrete slab is properly placed and supported, there is no requirement for slabs to be raised a specific distance above the ground, such as 12 inches. Instead, slabs are typically placed directly on a well-prepared subgrade, which provides a solid foundation.

Proper leveling of the ground is critical to ensure that the slab sits evenly and to prevent future issues like cracking or settling. Similarly, the use of reinforcement bars, or rebar, is commonly employed to enhance the tensile strength of the concrete. Appropriate curing time is also essential for concrete to achieve its intended strength and durability — ensuring that the curing process is followed allows the concrete to hydrate properly.

Understanding these principles helps in laying a successful concrete slab on grade, highlighting that placing the slab above ground by a certain amount is not a standard requirement.