G1 - Use Concrete Types, Materials, Additives, and Treatments Flashcards
What is the usual amount of overlap for reinforcing steel, if it is not specified by an engineer?
24 bar diameters
Pre-tensioned or post-tensioned concrete are both forms of pre-stressed concrete.
True
How should the cement paste be bonded in good reinforced concrete?
Bonded to the aggregate and the reinforcing steel
What is the additive used to help concrete resist damage from numerous freeze-thaw cycles?
Air entrainment
What are the similarities that make steel and concrete compatible?
Thermal expansion and contraction
What type of cement is used for high early strength concrete?
Type 30 hydraulic cement
What are the characteristics of aggregates in an economical concrete mix?
The largest course aggregate that is practical and a blend of smaller and fine aggregates
What does high slump concrete require?
Little or no vibration
Gunnite is a term used for concrete that is applied with compressed air. What is another term for this type of concrete?
shotcrete
Which is the easiest to cool in order to reduce the temperature of the concrete mix?
Water
What is the effect of adding extra water to a concrete mix in hot weather?
Weaker concrete
What is the most important characteristics of aggregate in good quality concrete?
Clean, hard, durable
What is LH portland cement used for?
Mass concrete pours
How are proportions measured when designing the water to cement ratio for concrete?
By weight
In a concrete mix, the maximum size of the aggregates should not exceed ______ of the smallest dimension of an un-reinforced concrete member.
One-fifth
What is the purpose of expansive cement in concrete?
Patching cracks and holes in concrete work
How does air entraining affect the behaviour of plastic concrete?
Reduces bleed water
How is the slump measured when testing concrete for consistency using a slump cone?
from the top of the cone to the top of the concrete pile
Which type of cement is used during cold weather concreting?
HE
What is the goal of a low water-cement ratio in concrete?
Strong concrete
What is the maximum size of fine aggregates?
4 mm
Which of the following lists contain materials that are detrimental to concrete?
- Acids, salts and alkalis
- Animal fats, milk, vinegar and brine
- Petroleum oils and coal tar distillates
What is the most widely used pozzolan in BC?
Fly ash
What can be the negative result of adding calcium chloride to a concrete mix?
Corrosion of on-coated re-enforcing steal
What is added to the concrete mix to increase the time for placing concrete during hot weather?
A retarder
What is the purpose of pigments?
To color concrete before or after placing
Which of the following statements about admixtures is true?
They are added to concrete during mixing
What is a drawback of metallic aggregate grouts?
They could stain the concrete in wet weather
What is “cementation”?
The use of liquid grout
