Precast Casting, Finishing and Curing Procedure

Purpose. Describes how precast concrete elements are prepared, cast, finished, cured, stripped and recorded at Bundamba to meet the drawings, the mix design and the Australian Standard for precast concrete elements.

1.Scope

This procedure covers every element cast at the Bundamba yard from mould preparation to placement in the storage yard. It must be read with the reinforcement fabrication work instruction, the lifting insert work instruction and the batch plant operating instruction.

2.Pre-pour inspection

Before concrete is ordered, the leading hand must inspect the mould against the pre-pour checklist and the current drawing revision. Reinforcement, cover, cast-in items, lifting inserts and void formers must be checked and the checklist must be signed by the leading hand and the quality inspector. Concrete must not be batched for a mould that has not passed the pre-pour inspection.

• Mould dimensions and squareness within tolerance
• Release agent applied and excess removed
• Reinforcement grade, spacing and cover as drawn
• Cast-in items and lifting inserts of the specified type and position
• Drawing revision recorded on the element record

3.Batching and placing

Concrete must be batched to the approved mix design for the element and the batch record must show the actual quantities, slump and concrete temperature. Concrete must be placed within the time limit on the mix design and compacted with vibrators in the pattern shown on the work instruction. Test cylinders must be taken for each pour as scheduled by the laboratory.

4.Finishing

The exposed face must be finished to the surface class on the drawing. Finishing must not start until bleed water has gone. Edges must be tooled and identification, including the element number, batch number and pour date, must be marked on the element in the position shown on the drawing.

5.Curing

Elements must be covered or steam cured immediately after finishing. Curing temperature and duration must be recorded on the element record at the intervals stated in the work instruction. Elements must not be stripped until the laboratory confirms the stripping strength from the matched cylinders.

6.Stripping and lifting

Only lifting inserts of the type shown on the drawing will be used and only with the matching lifting clutch. The crane operator and dogger must check the lifting plan and the element weight before the lift. Damaged inserts must be reported and the element must be held until an engineer confirms the lifting method.

7.Post-strip inspection and records

The quality inspector must inspect each element for dimensions, surface finish, cracks and honeycombing and must record the result in the quality test register. Nonconforming elements must be tagged and moved to the hold area. The element record and the batch record must be filed on the day of stripping.