Introduction to Concrete Flashcards
List the four main components of concrete.
- Fine Aggregates
- Coarse Aggregates
- Cement Paste (Portland cement)
- Water
Concrete has a very high tensile strength.
A) True
B) False
False
Concrete sets as the chemical process ________ begins.
Hydration.
High early strength Portland cement is known as type __________ cement.
3A-air-entraining
The __________ possible size of coarse aggregate should always be used.
Largest
A simple test for the mixing water when creating concrete is that the water should be ___________.
Potable (drinkable)
In mixing concrete, the ratio of _______ to _______ is the most critical.
Water (1) to Concrete (2)
What are the five strengths of concrete?
- High compressive strength
- Good wear resistance
- Low porosity
- Low Maintenance
- Ability to be moulded into any shape
What are the four weaknesses of concrete as a building material?
- Low tensile strength
- Tendency to shrink upon curing
- Brittleness
- High weight
What is concrete?
Concrete is a mix of cement paste and natural rock aggregates.
What is cement paste?
Cement pasts is a mix of cement and water that fills the void between every aggregate material and acts as a glue that bonds the ingredients together.
What are the possible legal outcomes if a concrete truck driver is asked to add water to the mix at the site?
The driver will record the request for additional water on the delivery ticket and the concrete supplier will not be responsible for any reduced quality.
Concrete is designed to attain its full strength in _____ days.
28
The compressive strength of concrete is denoted in ______ in the imperial system and _____ in the metric system.
Psi
MPa
The test for consistency of concrete is called the ______ test.
Slump
What is Porosity?
The ratio of voids in the concrete to the total concrete volume.
What is the mix of aggregate by volume in 1:2:3?
1 part cement
2 parts sand
3 parts gravel
Concrete gains _____ of its strength in the first 3 to 7 days.
50%
The amount of air-entrained air is usually between ____ and ____ of the volume of the concrete.
5% and 8%
The test for the consistency of concrete is called the ______ test.
Slump
In cold climates, the additive ________ must be ordered for all concrete that will be exposed to freeze-thaw cycles.
Air-entrainment
Concrete that is to be pumped should have _______ coarse aggregate and ______ sand content.
Smaller
Higher
The maximum time allowed for placement of the concrete from time the water is added is _________.
2 hours
What personal protective devices should a worker wear when working with concrete?
Safety glasses and long pants, rubber boots and gloves.
