PRECAST CONCRETE CONSTRUCTION

Precast concrete

•       Enables faster programme times - not affected by weather or labour shortages.

•       Improves build ability - early enclosure of dry envelope enables follow-on trades to start sooner.

•       Produces a high standard of workmanship in factory conditions - reduces potential for accidents, addresses on-site skill shortage.

•       Has a high quality finish that can be left exposed - concrete's thermal properties can be exploited in low-energy buildings.

PRIMARY FUNCTIONS                  

•       KEEP WATER OUT

•       PREVENT AIR LEAKAGE

•       CONTROL LIGHT

•       CONTROL RADIATION OF HEAT

•       CONTROL CONDUCTION OF HEAT

•       CONTROL SOUND

 SECONDARY FUNCTIONS

•       RESIST WIND FORCES

•       CONTROL WATER VAPOR

•       ADJUST TO MOVEMENT

•       THERMAL & MOISTURE EXPANSION/CONTRACTION

•       STRUCTURAL MOVEMENTS

•       RESIST FIRE

•       WEATHER GRACEFULLY

•       EASY TO INSTALL

Architectural precast concrete provides architects with an exciting medium when designing facades for a wide range of buildings, from healthcare facilities to shopping malls, commercial office buildings to sports stadiums.

    Precast concrete provides:

•          Complete thermal protection

•          Continuous air/vapor barrier

•          Effective rain screens

•          Superior lifespan

•          Reduced construction schedule and on-site

               labour

•           High quality control standards

•           Numerous finish options and colors

PRECAST BUILDING SYSTEM

•       Precast concrete frame

•       Precast concrete wall

•       Precast concrete floor

Precast concrete frame

•       Description

                                                             
Precast concrete frames involve an entire structure being fabricated off-site. In addition, structural components can be supplied for incorporation into a structure on-site. Frames can simultaneously achieve both structural and decorative design requirements - a wide variety of mixes, colours and finishes can be accommodated. Architecturally-finished precast structures can be left exposed to exploit concrete's high thermal capacity in a building's "green" energy management system.

•       Process

Precast concrete frames are cast in the same way as precast concrete cladding, but as they are designed as structural elements have heavier reinforcement than is required for non-structural cladding. Elegant connections are required between columns and beams to transfer considerable forces without adversely affecting the visual appearance of the frame.

•       Benefits

Precast concrete frames

•       Enable faster programme times - not affected by weather or labour shortages.

•       Improve buildability - structure is fabricated off-site for rapid erection on-site

•       Produce a high standard of workmanship in factory conditions - reduces potential for accidents, addresses on-site skill shortage.

•       Have a high quality finish that can be left exposed - concrete's thermal properties can be exploited in low-energy buildings.

2.Precast concrete wall

•       Precast wall are used for internal & external walls, lift shafts, central cores ect. Precast wall system are mostly used in domestic construction, both for individual housing & for apartments. The solution can be considered as the industrialized from of cast in-situ walls or classical brick or block masonry walls.

•       The precast walls can be load bearing or only partition walls. The surface of the elements is smooth on both sides & ready for painting or wall papering.

•       Precast walls offer the advantage of speed of construction, smooth surface finishing, acoustic insulation & fire resistance

3.Precast concrete Floor

•       The principle advantages of precast floors are speed of construction, absence of scaffolding, large variety of types, large span capacity, & economy.

•       Precats floors can also be classified according to their manufacture into totally & partially precast floors.

•       Totally precast floors are composed of units, which are totally cast at the plant. After erection, the units are connected to the structure & the longitudinal joints are grouted.In some cases a cast in-situ structural topping screed is added.

•       Partially precast floors are composed of a precast part & a cast in-situ part. Both parts are working together at the final stage to achieve the composite structural capacity. The main totally precast floor & roof types are described hereafter.

TENDENCIES IN PRECAST CONCRETE

•       . Structural efficiency

•       Flexibility in use

•       Optimum use of materials

•       Speed of construction

•       Quality consciousness

•       Adaptability

•       Protection of the environment

Advantages of Precast Concrete

•       Less expensive than real brick.

•       Does not require an extensive footing like a real masonry wall. Can be reset should it ever shift.

•       More durable than real masonry - no mortar joints to let water in.

•       Installs quickly and easily - most can be done in one day.

•       Maintenance free - No need to paint or periodically replace slats as you would with wood fences.

Disadvantage of precast concrete

•       System building is less flexible in its design concept than purpose-mode structures

•       Most design briefs can be fulfilled without too much modification to the original concept

•       Structural connection between the precast concrete units can present both design & contractual problems