Fig. 14 shows a reinforced concrete beam used in a building structure. The beam contains steel reinforcing bars. The metal has been selected for its specifi...

(a) Reinforced concrete is classified as a composite material because it is made from two different materials combined together to create improved properties [1]. The concrete (a mixture of cement, sand, aggregate, and water) acts as the matrix, while the steel reinforcing bars act as the reinforcement. Neither material alone would perform as well as the two together.

(b) The role of the steel bars relates to how concrete handles different types of force. Concrete is strong in compression (it resists being crushed) but weak in tension (it cracks easily when pulled apart or stretched) [1]. When a beam is loaded, the top surface is compressed while the bottom surface is stretched. The steel bars, which have high tensile strength, are positioned in the lower part of the beam to resist the tensile forces, preventing the concrete from cracking and allowing the beam to support bending loads without failure [1].

(c) Two advantages of using reinforced concrete in building structures:

1. Very strong and durable [1] - reinforced concrete can withstand large compressive and tensile loads, and it lasts for decades with minimal deterioration, making it suitable for structural elements such as beams, columns, and foundations.
2. Fire resistant [1] - unlike steel, which loses strength at high temperatures and can buckle, concrete does not burn and retains its structural integrity during a fire, providing important protection for the building and its occupants.

Other valid advantages include: it can be cast into any shape using formwork or moulds; it is relatively low cost compared to an all-steel frame; and it requires low maintenance once set.