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When the concrete in compressed at early stages the air voids will close and we will have less voids, hence the air void decrease the compressive strength of concrete so reducing it will increase the strength!
No it helps in tensile strength mainly.
When a concrete slab is subject to compression and the steel into tension before any substantial service loads are applied, puts both building materials into their strongest states. The result is a stiffer concrete slab that actively is compressed and has more capacity to resist tensile forces.
The compressive strength of concrete is the same but the load carrying capacity will definitely increase when it is post-tensioned slab.
yes through triaxial behavior of the material
when you post tension the concrete basically you are increasing the strength of concrete to bear the more tension when there is huge loading like bridges etc and steel can have less tension forces. so by post tension the concrete you increase its strength to take more load.
Absolutely it can, because due to posttensioning both steel and concrete are at the peak of their strengths (increased strength), thus making its possible to resist loads when applied.
Because post tensioning will induce some negative moment into slab/beam which means compression fibre is receiving some tension and tension fibre is receiving some compression. What this does is when you have the slab/beam loaded it will have additional strength because of some negative moment already induced so your positive moment would be lesser compared to your traditional beam/slab. Also this will help you out with deflection as well.
Post tension slabs require high grade concrete strength thus increasing the strength capacity of concrete at compression fiber.
