Which component is essential in preventing cracks in concrete due to stress?

Rebar, or reinforcing steel bars, plays a crucial role in preventing cracks in concrete that can arise from tensile stress. Concrete is strong in compression but relatively weak in tension, meaning it can easily crack when subjected to tensile forces. By incorporating rebar into concrete structures, the tensile strength of the concrete is significantly enhanced.

Rebar works by providing additional support and stability to the concrete. When the concrete begins to crack under stress, the rebar helps to hold the pieces together and mitigates the movement that could lead to larger cracks or structural failure. This reinforcement is particularly important in areas of high stress, such as beams, slabs, and foundation walls.

While other options may also contribute to the overall durability and integrity of concrete, rebar is specifically designed for reinforcing the tensile capacity of concrete. Fiber mesh, for example, is used to improve the concrete's resistance to plastic shrinkage cracking and may provide some level of tensile strength, but it does not match the effectiveness of rebar in addressing stress-related cracking.