Concrete Flashcards
Cement is
a finely ground material,
chemically active when combined with water, and
provides the binding medium.
Three main components of concrete
Cement
Water
Aggregates
Water
that is free of excessive amounts of salts, dissolved organic matter or extra impurities that will interfere with the hydration process of the cement.
Aggregates
are the filler material, usually in two size ranges, coarse and fine. Course aggregates are obtained as a quarried product and the fine ag is naturally occurring sand or gravel.
Compressive strength of concrete
15-50 Mpa (mega pascals)
Tensile strength of concrete
3-5 Mpa
Name of chemical reaction when cement is mixed with water
Hydration process
Plastic state/stage of concrete means
that it is not yet set or cured.
Why is it important all constituents of plastic concrete remain uniformly distributed?
To ensure uniform level of strength throughout the concrete.
Purpose of slump test on a concrete batch
To evaluate the workability and consistency of the concrete.
Why is concrete strength measured on a 28 day period?
Because at 28 days it has achieved 99% of its final strength.
Two main types of sample obtained from concrete delivered on site:
- Representative sample
- Uniform sample
