BCGBC4010A Apply structural principles to residential low-rise constructions

Structural principles - Structural members

Concrete slabs 

Ground slabs - Slab preparation
A photo shows a building site that has been prepared for a concrete pour of a ground slab. A description of the photo is provided further on. Within this photo you are asked to identify the following:
•	Formwork
•	Trench
•	Steel reinforcement
•	Vapour barrier
•	Bar chairs
•	Stiffening beam
•	Stake.
Description of the photo
Lengths of timber are arranged around the perimeter of the area to be concreted. These are held in place by star pickets that have brightly yellow plastic caps on top.
Excavation has been made around the inside perimeter of the area to be concreted, and additional excavation has been made in a grid pattern along the length and width of this area.
Black plastic sheeting has been placed over the entire area. Plastic stands have been placed at regular intervals on top of this sheeting, and these hold a metal grid in place a little above the plastic sheeting.
Identify which parts of the photo description match each of the terms listed above.

Answers
Formwork refers to the lengths of timber arranged around the perimeter of the area to be concreted.
Trench refers to the excavations around the inside perimeter of the area to be concreted.
Steel reinforcement is the metal grid that is held in place a little above the plastic sheeting.

The plastic sheeting forms the vapour barrier.
Bar chairs are the plastic stands that are placed at regular intervals on top of the plastic sheeting, and these hold the steel reinforcement in place a little above the plastic sheeting.
Stiffening beam refers to the additional excavation that has been made in a grid pattern along the length and width of the area to be concreted.
Stakes are the star pickets that have brightly yellow plastic caps on top. (These caps are used for safety both to cover the tops of the stakes and to make them more visible.)

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