Pre-Stressed and Pre-Cast Concrete

Pre-Cast Concrete frames

Structural elements (columns, beams, slabs) that are cast and cured in a factory, then transported to the construction site for assembly

Advantages of Pre-Cast Concrete

• Faster construction

• High quality control (factory production)

• Reduced site labor

• Less weather dependency

• Cleaner construction site

Disadvantages of Pre-Cast Concrete

• Transportation challenges

• Heavy lifting equipment required

• Connection detailing is critical

• Higher initial cost

Common Applications of Pre-Cast Concrete

• Commercial buildings

• Warehouses

• Parking garages

• Schools and institutional buildings

Components of Pre-Cast Concrete Frames

• Precast columns

• Precast beams

• Precast floor slabs

• Connection joints

Construction Process (Pre-Cast Concrete)

1. Design and shop drawings

2. Casting in factory moulds

3. Curing

4. Transportation to site

5. Lifting and placement

6. Connecting joints

Pre-Stressed Concrete

Concrete in which internal stresses are introduced before external loads are applied, to counteract tensile stresses.

It improves:

• Load-carrying capacity

• Crack resistance

• Span length

Why Pre-Stressed Concrete?

• Compresses the concrete before loading

• Reduces tensile cracking

• Allows longer spans

• Uses less material

Types of Pre-Stressing

• Pre-Tensioning

• Post-Tensioning

Pre-Tensioning

1. Steel tendons are stretched before concrete is poured.

2. Concrete is cast around stretched tendons.

3. After curing, tendons are released.

4. Compression is transferred to concrete.

Common Use: Precast beams, Railway sleepers, Floor planks

Post-Tensioning

1. Concrete is cast with ducts inside.

2. Steel tendons are inserted after concrete hardens.

3. Tendons are tensioned and anchored.

Common Use: Bridges, Long-span slabs, Multi-story buildings

Advantages of Pre-Stressed Concrete

• Longer spans

• Thinner slabs

• Reduced cracking

• Better durability

• Material savings

Disadvantages of Pre-Stressed Concrete

• Requires skilled labor

• Specialized equipment

• Higher initial cost

• Careful quality control required