Why is rebar commonly used in concrete flatwork?

Reinforcing bar, or rebar, is commonly used in concrete flatwork to provide tensile strength and resist cracking. Concrete, while very strong in compression, is relatively weak in tension. When stresses occur, such as those from loads, thermal changes, or shrinkage, the tension forces can lead to cracking. By embedding rebar within the concrete, tensile forces are transferred evenly, which helps to hold the concrete together and maintain its integrity, minimizing the likelihood and severity of cracks. This enhances the durability and lifespan of the flatwork, ensuring it can better withstand various stresses over time.

The other options do not accurately represent the primary purpose of rebar. For instance, while curing processes are important, they are typically managed through moisture retention, temperature control, and other methods rather than through the incorporation of rebar. The usage of rebar does not fundamentally enhance the surface finish of concrete; surface treatments and finishing techniques are utilized for that purpose instead. Lastly, while rebar does add some weight to the concrete, it is not used for this reason; the focus is on its structural benefits rather than increasing the weight.