Reinforced Cement Concrete (RCC)
Definition of Reinforced Cement Concrete
Reinforced Cement Concrete (RCC) is a composite building material consisting of structural concrete reinforced with a reinforcing material like steel. The most common reinforcement used is steel, due to its complimentary properties and it is called steel reinforced cement concrete or simply Reinforced Cement Concrete.
Steel bars embedded in concrete are called as ‘reinforcing bars or reinforcement’. You can read what makes steel suitable for reinforced concrete here. Reinforcing bars are available in two major grades, mild steel and high yield strength steel. Steel fabric made from cold drawn steel wires welded to form a mesh are also used as reinforcement in RCC. Fiber reinforced concrete are also popular in construction industry.
Concrete:
Structural concrete is the most commonly used construction material, used up at a rate of about one ton for every living human being. Man uses no material other than water in such tremendous quantity. Concrete is the most important building material, playing a part in all infrastructure projects. It can be molded into different shapes using suitable formwork.
Concrete is a heterogeneous mixture of cement, fine aggregate (sand), coarse aggregate (boulders or gravels) and water which solidifies into a strong mass due to the Hydration of Cement. Apart from these components, large number of additives called admixtures are also added to enhance the properties of concrete like workability, durability, time of setting etc.
Why is Reinforced Concrete better than Concrete?
Plain concrete is strong in compression, but it is weak in bending. Too weak that its tensile strength is around one tenth of its compressive strength. When plain concrete member is subjected to bending, it develops cracks and ruptures. For the same reason plain concrete is not used where bending action can occur. Tensile strength is defined as the ability to resist bending forces. Bending forces causes tensile stresses in flexural members like beams and columns. Plain concrete when reinforced with steel, which is more than hundred times stronger than concrete in tension, the overall capacity of plain concrete in bending is enhanced.
The steel bars compensate the concrete’s incapability for tensile resistance, effectively taking up all the tension, acting monolithically with concrete. So, when concrete and steel bars combine to act against forces result in good strength. Similar to how human bones reinforces the flesh and mass around it.
Consider a simply supported beam carrying uniformly distributed load over the whole span. When the load is applied, the mode of deflection primarily occurs is bending. As a result, there will be compression on the top of the beam and tension at the bottom part. Since concrete is weak in tension reinforcing bars will be provided in the lower portion of the beams to avoid cracking of concrete in tension zone.
What is reinforced concrete used for?
Reinforced concrete is used for all structural members subject to bending. From simple building components like Beam, Columns, Slabs, shear walls and Foundations to heavy structures like bridge piers, girders and dams are constructed with reinforced cement concrete. Reinforced cement concrete can be insitu concreted or precast concrete.
What are the Advantages of reinforced concrete?
Concrete and steel bars: Since RCC have both the elements with the properties of concrete which is strong in compression and steel good in tension it gives the advantage of both.
Casted into any shape: Fresh concrete will be in the form of fluid and so it can be poured and casted into any shape. It gives easiness to the engineer to decide the shape of structure based on architectural aspects.
Resistant to fire and weather: RCC with proper cover will withstand to fire for about 3 – 4 hours. RCC will also survive any type of weather with proper quality control and durability considerations.
Maintenance: After the completion of work low maintenance is needed for concrete structures compared to the other (steel and timber) type of structures.
Availability: Steel and Concrete are a commonly used construction material and so it is easily available to prepare reinforced cement concrete.
Economical: It is economical compared to the other materials like steel structure.
Rigidity: Reinforced Concrete members are good in rigidity due to their stiffness.
Challenges of using RCC
Time: Longer duration is needed for this type of construction. Reinforced concrete (RC) structures will attain its maximum strength only after 28 days. Therefore, it is a slow process and cannot be used for immediate works. Even though the strength gain can be accelerated with admixtures.
Requires form works: The process of forming involves the construction and removal of formworks. the proper forms must be constructed at the particular size and shape and pouring of concrete is done. After hardening of concrete, the forms are removed. For both the process labors are labor intensive.
Volume change: Concrete changes its volume with time due to shrinkage. This may cause cracking issues if not properly considered in design.