Quality Concrete Flashcards
For concrete to set quickly, Type ________ concrete should be used to produce high early strenght?
- Type III.
What is the result of too much water in a concrete mix?
- Higher Slump & Lower Strength
Which is a characteristic of air-entrainment concrete?
- Increases Workability.
When can fly ash be used in the calculation of minimum cement content for a concrete mix?
- When allowed by specifier.
Which type of foundation would generally be specified when the allowable bearing capacity of the soil is very low to great depths?
- Mat, Raft, or Floating
The maximum deliver time for ready-mix concrete is _______?
- 1.5 hours.
What would reduce the lateral pressure of concrete forms?
- Slower Placement.
The main purpose for steel reinforcement is to resist what type of force?
- Tension Forces.
A #5 bar has what characteristics?
- 5/8” or .625 Diameter ; 0.31in2 ; 1.043 lbs/ft.
What is theeffect of lowering the top bar or raising the lower bar by 1/2” more than specified in a 6” slab?
- Reduces carrying load by 20%.
Control joint cuts in a slab should be to a depth of ________ the slab thickness?
- 1/4(th).
Within how many hours after placement should concrete joints be sawn?
- 4-12(hours).
Which type of joint is used to control cracks where placement of concrete is interrupted?
- Construction Joints.
In a mat slab, generally, where below the top is the steel located?
- 2” Below the top.
Welded wire fabric is located where below the top is the steel located?
- Upper part to prevent cracks from opening.
