Practice/Trade: Concrete Flashcards
When pouring of the concrete slab foundation, when should the subgrade be lightly moistened prior to pouring the slab?
A. One day before concrete is poured to allow the water to penetrate.
B. Prior to pouring the concrete.
C. When temperatures will exceed 90° F.
D. When Type III concrete is being used.
B. Prior to pouring the concrete.
When pouring concrete, what type of aggregate would allow concrete to pump easier?
A. Pea gravel.
B. Rounded such as river gravel.
C. Sand.
D. Crushed concrete.
B. Rounded such as river gravel.
When is it acceptable to pour concrete over frozen subgrade?
A. Never.
B. If the ground is moistened before pouring.
C. If chemical additive is added to the concrete mix to lower the freezing point.
D. If the temperature of the concrete is maintained above freezing for 48 hours after it is poured
A. Never.
Bleeding” is defined as the
A. release of trapped air in the concrete.
B. water rising to the surface of the concrete.
C. separation of sand from the finer concrete.
D. separation of the sand from the coarser gravel.
B. water rising to the surface of the concrete.
When concrete is placed during hot weather, cracks resulting from surface shrinkage can be caused by?
A. Excess wetting of the subgrade.
B. Failure to broom the surface.
C. Rapid drying of the concrete at the slab surface.
D. Excessive water in the concrete.
C. Rapid drying of the concrete at the slab surface.
When building a slab on grade, what action would be performed last?
A. Fine grading.
B. Excavating.
C. Forming.
D. Placing reinforcing steel.
D. Placing reinforcing steel.
The order in which a slab on grade is built is excavating, fine grading, forming, then placing reinforcing steel.
