Precast in particular

This Issue This is a part of the Concrete feature

By - , Build 142

As prefabrication comes into its own, so does precast concrete with its prefab benefits, design versatility and ease of use on difficult sites.

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WITH APPROPRIATE design and the correct use of materials and manufacturing processes overseen by skilled personnel, precast concrete provides the strength and durability that is synonymous with concrete.

Manufactured in a dedicated off-site facility, precast concrete can meet tight quality controls, while its portability is ideal for transport and rapid on-site erection.

Precast is all around

Precast concrete components can be found throughout the built environment with building applications including offices and residences, correctional facilities, retail complexes and multi-level car parking structures.

For specific building components, precast concrete can be used for floor, wall, column, service core and stairway requirements.

Precast prestressed concrete is also used in highway construction, rail and pedestrian bridges and in civil applications for tunnels and mining infrastructure. Familiar precast elements include concrete poles and retaining and noise walls, as well as road barriers.

Many benefits

Precast concrete offers a range of advantages that differentiate it from in situ concrete construction. Combined, they provide a cost-effective construction solution.

Enhanced durability

Concrete’s ability to resist the ravages of the environment is well recognised. Fabrication in a controlled setting, where mix design, compaction and curing can be closely monitored, serves to enhance the durability of precast concrete.

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Fire resistance

Precast concrete is non-flammable and non-combustible and an extremely effective fire shield. Most concrete structures survive fire and can be repaired to reduce inconvenience and cost.

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Thermal and acoustic properties

The mass of internal precast concrete helps reduce temperature fluctuations – when exposed to the sun, it absorbs heat during the day and releases it through the night. This mass also provides sound separation between adjoining rooms and from exterior sources.

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Design versatility

The initial plasticity of concrete allows for complex structural and architectural shapes to be formed. This, combined with a myriad of colours, formliner profiles and surface finishes, means precast concrete remains popular with designers.

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Fast construction

As soon as drawings have been approved, the manufacture of precast components can begin off site while on-site foundation work gets underway. The process overlap means a shortened construction timeline.

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Structural capability

Loadbearing precast concrete wall panels and columns form a critical part of the structural frame, providing support for floors and roof. Reinforcement, including prestressing, ensures the structural capability of precast components as required, while connections are constantly evolving.

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Sustainable aspects

Precast concrete’s sustainability features include using greywater and recycled concrete aggregate, while off-site manufacture means optimum use of constituent materials and reducing on-site health and safety hazards.

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For more

Visit www.ccanz.org.nz and www.precastnz.org.nz or see the Precast concrete handbook (2009) published by NPCAA and CIA.

Download the PDF

More articles about these topics

Articles are correct at the time of publication but may have since become outdated.

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