Short Answer:

Prestressed concrete offers many advantages such as higher strength, better crack resistance, longer spans, and reduced material usage, making it ideal for bridges, high-rise buildings, and large slabs. It allows thinner and lighter structural elements and improves durability.

However, disadvantages include higher initial cost, complex construction process, and need for skilled labor and equipment. It requires careful design and execution to avoid failure. Despite this, its long-term benefits often make it more economical in large-scale projects.

Detailed Explanation:

Advantages and disadvantages of prestressed concrete

Prestressed concrete is a modern construction material where internal stresses are introduced intentionally in the concrete to resist external loads more effectively. This is achieved by tensioning high-strength steel tendons within the concrete, either before (pre-tensioning) or after (post-tensioning) the concrete is cast. The main goal is to improve the concrete’s performance, especially in resisting tensile stresses, which concrete is naturally weak at handling.

While prestressed concrete provides several performance benefits, it also comes with some practical and economic challenges. Understanding both the advantages and disadvantages helps engineers decide where and when to use this technique effectively.

Advantages of Prestressed Concrete

1. Higher Load-Carrying Capacity
   Prestressed concrete can carry heavier loads than regular RCC structures because the concrete is kept in compression, which minimizes tension cracks.
2. Longer Spans
   It is especially beneficial for long-span structures like bridges and large roofs, reducing the need for intermediate supports and saving space.
3. Better Crack Control
   The compressive force applied through prestressing helps prevent the formation of cracks, leading to better durability and water tightness.
4. Material Efficiency
   Because of improved strength, less concrete and steel are needed, making the structure lighter and reducing dead load.
5. Improved Structural Behavior
   Prestressed members behave better under dynamic and cyclic loads like traffic, wind, or seismic forces, as the stress distribution is more balanced.
6. Reduced Maintenance
   As cracks are minimized, the structure requires less frequent repairs, increasing its lifespan.

Disadvantages of Prestressed Concrete

1. Higher Initial Cost
   Prestressing requires special equipment, high-strength steel, and expert labor, increasing the initial construction cost.
2. Complex Construction Process
   Tensioning steel tendons and anchoring them demands careful control and precision, making the process more technical compared to RCC.
3. Need for Skilled Supervision
   Skilled professionals must monitor every step – from tendon placement to tensioning – to ensure safety and success.
4. Risk of Accidental Damage
   If tendons or anchorages are damaged accidentally during construction or service, the structure may fail suddenly, unlike RCC which gives warning through cracking.
5. Limited Field Application for Pre-Tensioning
   Pre-tensioning is typically done in factories (precast), not on-site, making it less flexible for small or complex construction projects.

Conclusion:

Prestressed concrete offers significant benefits like longer spans, reduced cracking, and material savings, which make it ideal for large, demanding structures. However, it comes with higher costs, skilled requirements, and construction complexity. Despite these drawbacks, when used correctly, prestressed concrete ensures greater strength, durability, and economy over the life of the structure.