What is the primary material used in reinforced concrete masonry units (CMUs)?

The primary material used in reinforced concrete masonry units (CMUs) is cement. CMUs are made primarily of concrete, which is a composite material that consists of cement, aggregates (such as sand and gravel), and water. Cement acts as the binding agent in concrete, providing strength and durability.

Reinforcement, typically in the form of steel rebar, is added to these units to increase their structural integrity and resistance to tensile stresses. This combination of cement and aggregates gives CMUs their characteristic strength, making them suitable for various construction applications, including load-bearing walls, partitions, and foundations.

Other options like metal, wood, and glass do not form the primary composition of CMUs. Metal is often used as reinforcement, wood might be used in certain applications alongside concrete but is not a component of CMUs, and glass is not utilized in traditional concrete masonry units. Therefore, recognizing cement as the main ingredient emphasizes the role it plays in the overall functionality and performance of reinforced concrete masonry units.