Prestressed Concrete Piles

Introduction of prestressed concrete piles has reduced the weight of precast piles providing a advantage of easy handling. The weight of very large pile is reduced by casting 200 mm to 300 mm diameter fibre tubes inside the piles at the time of concreting. In casting prestressed concrete piles, the pretensioning cables required for each piles are subjected to the required pull (tension) in the casting bed. The fibre tube for forming void in the pile (if needed) is securely held in position in side the form work and the piles reinforced with the pre-tensioned cables are concreted in a row. The casting bed can be made to accommodate 2 to 5 lines of piles 120 to 150 metre long. Prestressed piles are provided with lifting hooks at 1/5 th of the pile length from each end.

In general, square prestressed concrete piles of length 50 times the thickness can be handled with a single point pick-up and up to 60 times the thickness with two point pick-up.  Piles 500 mm square and smaller are usually cast solid, whereas pile above 500 mm square may be cast with 200 mm to 300 mm diameter cored hole(void).

On account of their reduced weight, prestressed concrete piles have definite handling advantage over precast piles and as such they are getting increasingly popular these days. When compared with reinforced concrete piles, prestressed piles have proved to be extremely durable in tidal zones and for harbour installations, where unsupported lengths of the piles becomes considerable. Their load carrying capacity is high and they are capable of resisting uplift forces and combined moments. in addition, they can withstand extremely hard driving stresses which may be far more than that which a conventional type of reinforced concrete pile can bear.