In how many types can R.C.C. be classified into?
2
Classifying Reinforced Cement Concrete (R.C.C.) Types
Reinforced Cement Concrete, commonly known as R.C.C., is a composite material where concrete's compressive strength is combined with the tensile strength of reinforcement, usually steel bars. Understanding its classification helps in selecting the appropriate type for different construction purposes.
Based on how the reinforcement is introduced and acts within the concrete, R.C.C. is primarily classified into different types. This classification is fundamental in structural engineering.
Main Types of R.C.C.
R.C.C. can be broadly classified into two main types:
- Ordinary Reinforced Cement Concrete
- Prestressed Reinforced Cement Concrete
1. Ordinary Reinforced Cement Concrete
In ordinary R.C.C., steel reinforcement bars are placed within the concrete formwork before the concrete is poured. As the concrete hardens, it bonds with the steel, creating a composite material. The steel bars are primarily intended to resist the tensile stresses that the concrete alone cannot handle effectively. This is the most common type of R.C.C. used in buildings, bridges, and other structures.
2. Prestressed Reinforced Cement Concrete
Prestressed R.C.C. involves applying a pre-compression force to the concrete before it is subjected to external loads. This pre-compression is typically achieved by tensioning high-strength steel tendons or wires and then anchoring them to the concrete. When external loads are applied, this initial compression counteracts the tensile stresses that would normally develop, allowing the concrete section to remain largely in compression. This method is particularly advantageous for long-span beams, bridges, and heavy-load bearing structures as it results in more efficient use of materials and reduced cracking.
| Feature | Ordinary R.C.C. | Prestressed R.C.C. |
|---|---|---|
| Reinforcement State | Steel bars are passive until load is applied. | Steel tendons are tensioned (active) before service loads. |
| Primary Stress in Concrete | Compression (primarily under load, tension occurs) | Compression (maintained under service loads) |
| Cracking | Cracking occurs under tension at service loads. | Minimized or eliminated cracking under service loads. |
| Efficiency for Long Spans | Less efficient | More efficient |
| Cost | Generally lower | Generally higher (due to materials and technique) |
Thus, R.C.C. is classified into these two principal types based on whether internal stresses are introduced before external loading (prestressing) or if the reinforcement acts passively to resist loads (ordinary R.C.C.).
Revision Table: R.C.C. Classification Summary
| Classification Aspect | Details |
|---|---|
| Number of Main Types | 2 |
| Type 1 | Ordinary Reinforced Concrete |
| Type 2 | Prestressed Concrete |
| Ordinary R.C.C. Principle | Steel resists tension developed under load. |
| Prestressed R.C.C. Principle | Internal compression counteracts external tension. |
Additional Information: Exploring Prestressed Concrete
Prestressed concrete itself can be further classified based on the method and timing of tensioning the steel tendons:
- Pre-tensioned Concrete: The tendons are tensioned before the concrete is cast. Once the concrete gains sufficient strength, the tension in the tendons is released, and the stress is transferred to the concrete through bond. This is typically done in precast concrete plants.
- Post-tensioned Concrete: Ducts or sheaths are placed within the concrete formwork before casting. After the concrete has hardened, the tendons are threaded through the ducts and tensioned using jacks. The tendons are then anchored at the ends, and the ducts may be grouted. This method is often used for cast-in-place concrete structures.
These sub-classifications highlight the versatility and engineering considerations within the broader field of R.C.C. design and construction.
Important Questions from Introduction
In the following table, the left column contains the names of standard graph algorithms and the right column contains the time complexities of the algorithms. Here, n and m are number of vertices and edges, respectively. Match each algorithm with its time complexity.
List I List II Standard graph algorithms Time complexities A. Bellman‐Ford algorithm I. O(m*log n) B. Kruskal’s algorithm II. O(n 3) C. Floyd‐Warshall algorithm III. O(n*m) D. Topological sorting IV. O(n + m) Choose the correct answer from the options given below :
How many cards must be selected from a standard deck of 52 cards to guarantee that at least three hearts are present among them?
Match List 1 with List 2 and choose the correct answer from the code given below:
List I
(Graph Algorithm)
List II
(Time Complexity)
a) Dijkstra’s algorithm
i) Θ(E log E)
b) Kruskal’s algorithm
ii) Θ(V 3)
c) Floyd-Warshall algorithm
iii) Θ(V 2)
d) Topological sorting
iv) Θ(V + E)
Where V and E are the number of vertices and edges in graph respectively.
The solution of recurrence relation: T(n)=2T(sqrt(n)) + lg(n) is
Modulus of elasticity of concrete, E is calculated using:
