Benefits and limitations of prestressing concrete

The prestressing of concrete offers various benefits relating to conventional reinforced concrete (RC) devoid of prestressing. A completely prestressed concrete member is generally dependent on compression throughout service life. This adjusts various imperfections of concrete.

Given below, various advantages of a pre-stressed concrete member.

A) Section stays un-cracked under service loads
1. Curtailment of steel corrosion
* Strength is improved.
2. Full section is applied
* Greater moment of inertia (greater stiffness)
3. A smaller amount of deformations (better serviceability).
4. Rise in shear capacity
5. Appropriate for being utilized in pressure vessels, liquid retaining structures.
* Enhanced performance (resilience) under dynamic and fatigue loading.

B) High span-to-depth ratios
1. Higher spans are achieved with prestressing (bridges, buildings with large column-free spaces)
2. Standard values of span-to-depth ratios in slabs are provided herewith.

For the similar span, less depth relating to RC member.
* Decline in self weight
* More visual appeal because of slender sections
* More economical sections.

C) Best fit for precast construction The benefits of precast are given below :-

* Quick construction
* Superior quality control
* Less maintenance
* Ideal for repetitive construction
* Multiple application of formwork

Though, prestressing offers several benefits, there are some negative aspects also:-

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* Prestressing requires competent technology. So, the process is not so easy as compared to reinforced concrete.
* As high strength materials are used in prestressing, so they are quite expensive.
* There is extra cost in supporting equipments.
* Prestressing requires thorough quality control and examination.

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