Precast Concrete
Precast quality versus on site methods
- Controlled environment- alleviating all environmental factors sun, wind, rain.
- Control mix designs in house- high quality durable concrete (low W/Co ratios).
- Quality Assurance systems, post and pre pour checks.
Pre pour & Post pour audits- key manufacturing stages
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- Drawing
- Mould table to be clean and free of imperfections prior to set up
- Form work
- Set up dimensionally correct
- Reinforcement and cast in items respecting drawings
- Concrete preparation
- Placement of concrete
- Stripping
- Handling & storage
- Final inspection
Quality
- AS3610 for off-form concrete
- Class 2
- Always view samples or similar projects to create the right expectation
- Understand you are dealing with natural products
Timing
- Accurate scheduling, providing documentation is complete and sufficient lead times allowed for workshop detailing 9-12 weeks lead time currently
- Not effected by weather
Planning Production
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- Greater synergies could be realized in the manufacture of precast if repeat panels on elevations were able to be cast from bottom to top in a single mould. Current practice is level by level around the building.
- For this to happen give the manufacture greater lead times.
- Repetitive and standard features.
- Ensure documentation is complete, including workshop drawings; this allows for better planning at manufactures facilities.
- Be prepared to pay manufacture for off site payments for panels manufactured.
- Standard panel thickness
- Standard cast plates and fixings
Decorative concrete
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- Requires high degree of quality control.
- On site manufacture allows control and conditioning of raw materials, avoids contamination of materials; often experienced with premixed suppliers.
- Gives you control of water demand in concrete, maintaining integrity of water cement ratios. Inconsistent water demands and the practice of adding water will change colour and texture of concrete.
Panel Sizes
- Maximise panel area, panels @20m² or better, target 10 tonne for flat lift out of beds; also dependant on crane size and area on site.
- Minimise number of panels, effectively reducing labour, truck movements and cranage.
Lifting procedures
- Greater consideration required by all on lifting procedures to match site environment and practices of riggers.
- Design for lifting precast.
- Design to use proprietary lifting systems.
- Include erection teams in at early stages of project.
Safety awareness culture
- Employ correct lifting procedures.
- Use proprietary lifting system.
- Internal audits on safety procedures and JSA’a.
- Maintain housekeeping.
- Regular scheduled maintenance of cranes and equipment.
Transport
- Erection sequence determines loads.
- Site access for trucks.
- Planning will reduce transport costs.
Transport Restrictions
- Maximum height of panels in A frames 4.3 metres.
- Length to suit trailer configurations generally 12 metres, consider site application for riggers.
