What Is a Post-Tension Slab?

6 min readApr 15, 2022

Post Tension Slab has excessive energy in compression however is susceptible to tension. Since it’s far brittle it can crack abruptly after failure.

So, to make the concrete robust in tension and save you the unexpected fall apart of the shape we ought to offer tension-bearing substances like metal rods withinside the tension sector of the slab. Also Read: Monolithic Slab for Garage

Read Also, Detailed Estimate of the building. This technique is typically used for multistoried buildings. It is extra correct than the alternative techniques viz., the plinth place technique and unit base technique.

The price of a shape is calculated as the entire cubical contents (Volume of buildings) accelerated through the Local Cubic Rate.

But these days slabs are furnished tension with the assistance of tendons to lessen the quantity of hysteria presenting substances like metal rods. Also Read: What Is Isometric Projection

The slab that is subjected to tension with the assistance of tendons earlier than the casting of concrete for the slab or after the casting of concrete for the slab is referred to as pre-tensioned and post-tensioned slab respectively.

These kinds of slabs are used for decades for money in addition to time-saving purposes. Here we can speak best the post-tensioned slab in detail.

Tension withinside the post-tensioned slab is furnished in steps after casting of concrete for the slab. Generally, it’s far furnished in 7 days after which in 28 days, however, I advocate you to offer tension as according to design.

After presenting tension withinside the tendons we ought to grout with the assistance of cement, water, and a few chemicals (Intraplaster) for robust bonding with the assistance of a stress grouter. After that, the tendons cord is reduced and tightened with anchors. Also Read: Permeation Grouting Contractors

Require of Post Tensioning

Concrete has excessive compressive energy and metal has excessive tensile energy. Therefore, if a slab is ready for the use of this compound, the load-bearing ability of the slab is increased. It additionally will increase its efficiency.

Sometimes a heavy stay load comes at the shape whilst heavy pressure passes via its concrete slab. As a result, cracks and deformation arise withinside the concrete slab. Also Read: Folded Plates

To triumph over this problem, post-tensioning metal tendons are located withinside the slab earlier than concreting.

When the post-tensioning slab is stressed, the concrete is squeezed. In different words, compacted concrete will increase the compressive energy, and similarly, metal tendons boom the tensile energy of concrete. As a result, the energy of the concrete will increase.

Components of Post-Tension Slabs:

1. Tendons

The primary detail utilized in post-tensioning structures is referred to as tendons. Post-tensioning tendons are made of a couple of organizations of prestressing metal. Also Read: Advantages and Disadvantages of Stone

Which has a protecting coating against excessive energy. Which is located interior of a tube or casing in a concrete slab.

According to ASTM-416 TENDONS are used withinside the concrete slab. According to this, trendy sizes 0.50 and 0.60 mm are saved.

The everyday metal tendon used for post-tensioning ought to have a minimum yield of 243,000 psi.

2. Ducts

Claw coupling or welding overlap is provided as required in skinny sheet metallic pipes in post-tension slabs of five and six m in period respectively.

The tubes are related through an outside screw coupling and the outer face is sealed with PE tape. Also Read: Brick Construction Type

Watertight, abrasion-free, and fatigue-resistant plastic tubes also are to be had withinside the market. Which may be used withinside the post-anxiety slabs.

3. Anchors

Anchors are used to anchoring withinside the concrete. The primary feature of anchoring is to switch the pressure via the tendons to the concrete after the worrying manner is finished withinside the tendons.

Construction Process of Post Tension Slab

The set up of post-tensioning tendons in concrete calls for professional hard work and employees as required. Experienced in post-tension slab work.

The tendons are laid in concrete with traditional reinforcement. The role of the tendons is decided by the engineer in step with the shape design.

These tendons’ cable is held in plastic or metal tubes. So that the tendons are blanketed from touch with water withinside the concrete. Also Read: Crawl Space Footing

The post-tension slab is constant at one stop of the tendons with the use of an anchor and the alternative stop is saved open in a plastic pipe.

Where tension is emphasized through the anxiety manner. Couplers are used among tendons if a production joint is formed.

The alignment of the tendons is discovered all through concreting of the slab. So that their right role does now no longer change.

Once 75% energy of the concrete slab is achieved, or after approximately 27 days, pressure is carried out with the use of stressing jacks. Also Read: Well Points

Tensioning is finished with a strand with a pressure of 80% of the tensile energy above the tendons. For a 270 begin with a trendy 3-inch grade, the strand is given tensile energy of 33,000 pounds.

The metal expands all through the tensioning manner. And the concrete is shrinking. When the right tensioning pressure reaches the tendon, it’s far constant through the anchor.

The tendons through anchor are designed to have an everlasting mechanical connection withinside the concrete, to maintain the concrete in compression and the metal in tension. Also Read: Non Load Bearing Wall

Extra sticking out post-tension cable is reduced withinside the concrete slab. Non-decrease kind grouting is utilized in the area of anchoring.

Application of Post Tension Slab

Post-tensioning or PT slabs have to grow to be more and more famous use over the past 30 years. Initially, there have been issues with corrosion of the cables used in this technique.

But suitable substances and production techniques of tendons have eliminated the maximum of the issues.

Post anxiety slabs are utilized in a few not unusual place packages as follows:

Bridge designers have used PT slabs for each precast section and forged-in-area concrete in bridges. PT slab permits for an extended span and decreases cracks. Also Read: Silicone Roof Coating Problems
PT slabs are broadly used for slabs on grades, particularly wherein floor moves are in all likelihood to arise
PT slabs are used externally post-tensioning to enhance these days’ advanced structures. This technique is particularly used to face up to seismic forces.

Post Tension Slab Advantages

It has much less deflection after loading.
It has excessive fatigue energy
Fewer numbers of metals are used which decreases the risk of corrosion.
It is time-saving
Generally, it is ready on the web website online so no want to move it from one area to another. Also Read: How to Clean Sunbrella Cushions
It may be forged for a massive span due to the fact we ought to offer tension on the web website online.

Disadvantages of Post Tensioned Slab

Different tendons ought to be used for unique contributors like slab, beam, etc.
It is much less dependable and much less long-lasting than a pre-tension slab
It is more expensive compared to the pretension slab
Skilled human electricity is required.
Difficult to grout. Also Read: Kitchen Linoleum Flooring

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