Prestressed concrete has more or less replaced reinforced concrete as most suitable material for bridge construction due to its inherent advantages of high strength coupled with durability, energy absorption under dynamic loads, ability to resist repetitive loads, freedom from cracks, easy mould ability to desired shape, economy and ease of maintenance.

Anor planning example of planning an aircraft hanger is Boeing hanger at santa curv airport is in: Bombay prestressed hanger provides an uninterrupted area of 101m by 45.73m and roof consists of 10 barrel shells of 45.75m span with 12.2m chord width supported on longitudinal prestressed concrete edge beams and frontal beams are also prestressed and span over clear door openings is 48.8m and overall depth of beam is 6.1m soffit of beam and aircraft hanger was planned and designed and constructed by gammon Indian limited for international airports authority of India.

Concrete may be mixed using stationary mixes on job site or central mixes as used in ready mix plants and under usual conditions up to about 10% of mixing water should be placed in mixer drum before solid materials are added and re after water should be added uniformly with solid materials leaving about 10% to be added after all or materials are in drum.

The salient feature of basic reactor vessel of madras atomic power project and prestressed vessel consists of an inner containment monolithic structure made up of prestressed concrete wall and dome designed for maximum pressure and practically complete leak tightness is ensured by introduction of an outer reinforced masonry wall separated by an annular air space and is kept under small positive pressure intensity so that effective leakage into atmosphere is almost zero.

When concrete is deposited in layer it is allowed to sink due to its own weight to bottom of layer and n slowly withdrawn and during vibration of succeeding layers, vibrator should preferably penetrate surface of preceding layer by at least 150mm and good vibration should result in a surface without honey combing, aggregate or mortar pockets or excessive air bubbles.

Reinforced concrete are widely used for energy structures like dams, surge shafts in hydroelectric power stations and use of prestressed concrete biological shields for nuclear reactor and containment vessels of few several advantages and prestressed concrete pressure vessels can be triaxially prestressed resulting in higher load factors against limit states of service and ultimate failure and structural form normally used comprises a cylindrical concrete vessel capped with a shallow dome and cylindrical and spherical shapes have been used for oldbury and wylfa pressure vessels.

When vibrators are used for horizontal and vertical operation, spacing of points of vibration should be such that ir zones of influence overlap and when concrete is deposited in layers such as that in column, vibrator should be inserted vertically.

Prestressed concrete is ideally suited for construction of medium and long span bridges and at present reinforcements and prestressed concrete bridge decks from a major percentage of several types of bridges constructed throughout world.

The Bhima aqueduct constructed near solapur, Maharashtra has a continuous precast concrete circular tube prestressed both longitudinally and circumferentially and circular shape was planned to reduce Rugosity coefficient facilitating easy passage of water and aqueduct is 947m long with spans of 41.5m having a truncated circular cross section of 4.8 diameter with 3.75m roadway at top and average thickness of circular tube is 200mm and this aqueduct is an excellent example of planning hydraulic and highway elements in a single structure.

The Narora atomic plant consists of a double containment vessel and inner unit is a prestressed concrete cylindrical wall capped by a prestressed concrete cellular slab and outer wall is rigidly connected to foundation raft at base while inner prestressed wall is made monolithic with raft after stressing.