Strength
Concrete is strong in compression and weak in tension (compressive force:tensile force = 10:1). It cracks easily when subjected to bending and tension. Steel reinforcement is also strong in tension and weak in compression. As steel reinforcement is a thin linear quantity of material, it can easily buckle when under compression. By combining concrete and reinforcing bar, which have opposite properties, it is possible to create structures that are resistant to compression and tension.
Durability
Concrete is extremely durable. However, if the reinforcing steel bars rust, they will not be strong enough. In reinforced concrete, the strong alkaline concrete prevents corrosion of the reinforcing steel bars by preventing their oxidation. By adjusting the thickness of the concrete protecting the steel reinforcement, sufficient durability can be achieved.
Thermal deformation
If materials with different thermal expansions are combined, distortion may occur. Steel reinforcing bars and concrete have a close degree of expansion due to heat and changes in temperature do not cause problems. Specifically, the difference in expansion is about 0.01 mm for 1 m of reinforced concrete.
Cost
Reinforced concrete structures are rational structures that reduce the use of expensive steel. The cross section of a reinforced concrete column shows a large proportion of concrete and a small proportion of steel reinforcement. Reinforced concrete structures are rational structures, as the use of reinforcing steel can be reduced by using concrete to take the compression.
Conclusion
Reinforced concrete structures have been widely used as a construction material because of a number of convenient properties. In the process, deformed steel bars and pre-cast concrete were introduced. High-strength concrete has also been developed, making it increasingly possible to build high-rise buildings with reinforced concrete structures.
