What is post tensioned slab?
Post-tensioned (PT) slabs are typically flat slabs, band beam and slabs or ribbed slabs. PT slabs offer the thinnest slab type, as concrete is worked to its strengths, mostly being kept in compression. Longer spans can be achieved due to pre-stress, which can also be used to counteract deflections. Post tension slab is a combination of conventional slab reinforcement and additional protruding high-strength steel tendons, which are consequently subjected to tension after the concrete has set. This hybridization helps achieve the formation of a much thinner slab with a longer span devoid of any column-free spaces.
Why post tensioned slab used?
The benefit of a post tension slab is it’s higher Strength. Post-tensioned concrete is stronger and more flexible than conventional steel-reinforced concrete. According to the Concrete Network, post-tensioning helps reduce cracking from shrinkage as the concrete dries, and holds together any cracks that do form.
Advantages of Post Tension Slab
Post tension slabs are advantageous in many ways. Some of the major benefits of post tension slabs are as follows.
1. Reduced cost: Post tension slabs are excellent ways to construct stronger structures at an affordable price. There are many structures like parking garages as well as stadiums, since they are required to hold much more weight than average buildings, this slab becomes a viable option.
2. Flexibility in design: The designs made with this slab are sleek, require lesser space and give way to dynamic contours. All this makes them ideal for the expression of creativity in the building design.It lets us design longer spans in elevated members, like floors or beams.
3. Lesser usage of materials: Since the post tension slab is thin, the materials used with it are also lesser. Be it the thin beams, walls or supporting pillars of buildings, this compact concrete slab does not need bulky materials.It allows slabs and other structural members to be thinner.
4. Durability: Being a very strong substitute of the normal concrete, it lasts longer.It reduces or eliminates shrinkage cracking-therefore no joints, or fewer joints, are needed
Disadvantages of the post tension slab
Here are a few disadvantages of post tension slabs:
1.Corrosion: Since there are a number of tendons and wires spread inside the post tension slab, it can result in corrosion. But largely, this tendency to corrode depends on the quality of the material used.
2. Complexity of work: The post tension slab can be made only by skillful professionals. The local workers may not have the necessary skills required to prepare this complex slab.
3. Poor workmanship can lead to accidents: The main problem with using post tension slab is that if care is not taken while making it, it can lead to future mishaps. Many a times, ignorant workers do not fill the gaps of the tendons and wiring completely. These gaps cause corrosion of the wires which may break untimely, leading to some untoward events.
The post tension slab is one of the building blocks of the modern architecture and builders cannot think of making skyscrapers, longer bridges and marvelous structures without using it. A skilled and experienced work is one of the key requirements while making these slabs, on the other hand, carelessness in the manufacture process may lead to disastrous results.
Basic concept of Post Tensioned Slab
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Design of Post-tensioned Slab
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