What are the different types of tension and post tension system?

Some of the popular methods of post-tensioning in prestressed concrete are:

• Freyssinet system.
• Magnel system.
• Leonhardt system.
• Lee-McCall system.
• Gifford-Udall system.

What is post tensioning in concrete?

Post-tensioning is a method of prestressing in which the tendons are tensioned after the concrete has hardened and the prestressing force is primarily transferred to the concrete through the end anchorages.

How much tension is on a post tension slab?

A post tension slab is a concrete slab with steel cables running through it that have been placed under 33,000 +/- pounds of tension. This tension makes the concrete slab and foundation much stronger than concrete without reinforcement and helps reduce cracking.

What is post tension reinforcement?

Post tensioning is a technique for reinforcing concrete. Afterwards, once the concrete has gained strength but before the service loads are applied, the cables are pulled tight, or tensioned, and anchored against the outer edges of the concrete. Post-tensioning is a form of prestressing.

What is the benefit of a post tension slab?

It reduces or eliminates shrinkage cracking-therefore no joints, or fewer joints, are needed. Cracks that do form are held tightly together. It allows slabs and other structural members to be thinner. It allows us to build slabs on expansive or soft soils.

How does post tension work in precast concrete?

Pretension is the technique in which we are imparting tension in strands before placing the concrete. Post tensioning is done by forming a duct in which strands are pulled (tensioned) after the concrete gains it’s full strength. 2. Small sections are constructed.

What is the difference between pre tensioning and post tensioning?

Pretension is the technique in which we are imparting tension in strands before placing the concrete. Post tensioning is done by forming a duct in which strands are pulled (tensioned) after the concrete gains it’s full strength. This method is done due to bonding between concrete and steel.

What is the principle of post tensioning?

Working Principle of Post Tensioning When these post tensioned steel tendons are stressed, the concrete is squeezed, in other terms, the concrete is compacted which increases the compressive strength of the concrete and at the same time the steel tendons that are pulled increase the tensile strength.

Is a post tension slab better?

First off, one could argue that post-tensioning is superior to conventionally reinforced concrete in a pure engineering sense. The reason is because post-tensioning is a method of pre-compression, which means the concrete is put into a state of compression, which allows the concrete to take on flexure without cracking.

Should a post tension slab crack?

Post Tensioning or normal concrete floors will crack as you described two hours after it was poured.

Can a post tension slab be repaired?

Post tension (PT) tendon systems are primarily used for large slab construction projects. Since the early 1950’s, post tension tendons have been used in the design of concrete structures. For such critical structural element, the repair should only be completed using a certified, experienced repair contractor.

What does post tensioned concrete mean?

Post – tensioned concrete means that the concrete is poured and then the tension is applied-but it is still stressed before the loads are applied so it is still prestressed. Most precast, prestressed concrete is actually pre – tensioned -the steel is pulled before the concrete is poured.

What is the difference between post tensioning and prestressing?

According to the Concrete Network, post – tensioning helps reduce cracking from shrinkage as the concrete dries, and holds together any cracks that do form. Prestressing simply means that the steel is stressed (pulled or tensioned) before the concrete has to support the service loads.

What is pre-stressing concrete?

Pre-stressing is the important distinction between post tension concrete and conventionally reinforced concrete. You see, conventionally reinforced concrete simply means that there are no active stresses going on within the concrete until after the load that it is designed to resist is applied.

Can I cut post tension cables from my concrete slab?

The fact that every time a tenant improvement requires saw-cutting the concrete slab it will also require an engineer and contractor with expertise in avoiding or purposefully cutting post tension cables usually deters the use.