What is the method used for placing rebar in vertical applications?

The correct answer focuses on the proper method for placing rebar in vertical applications, which involves positioning it at specified spacing and filling cores with high slump concrete. This approach ensures that the rebar is adequately supported and incorporated into the structure, providing the necessary tensile strength to the masonry.

Rebar is critical in vertical applications as it helps reinforce the walls and enhance their load-bearing capacity. By properly spacing the rebar and filling the cores with high slump concrete, the material can effectively flow around the rebar, ensuring a strong bond and structural integrity. This method also allows for adequate coverage of the reinforcement, which is essential for preventing corrosion and ensuring durability over time.

In contrast, placing rebar flat on the surface or coiling it inside blocks does not provide the necessary structural support and can lead to weak points in the masonry. Embedding rebar in mortar is not a standard practice for vertical applications as it does not provide the same level of reinforcement as proper spacing and concrete filling do. Therefore, the first option represents the most effective and correct method for rebar placement in vertical masonry applications.