T1-1: The Reaction of Portland Cement with Water Flashcards
What is the main binding phase in concrete called?
[NAQ] table of different constituents
For Tricalcium silicate (alite), what is:
A. the chemical formula
B. shorthand
C. % of constituent in Portland cement clinker
A. see image
B. C3S
C. 50-70%
For Dicalcium silicate (Belite), what is:
A. the chemical formula
B. shorthand
C. % of constituent in Portland cement clinker
A. see image
B. C2S
C. 10-25%
For Tricalcium aluminate, what is:
A. the chemical formula
B. shorthand
C. % of constituent in Portland cement clinker
A. see image
B. C3A
C. 5-10%
For Calcium aluminoferrite, what is:
A. the chemical formula
B. shorthand
C. % of constituent in Portland cement clinker
A. see image
B. C4AF
C. 5-15%
What are the four main constituents of Portland cement clinker, corresponding to the shorthands:
- C3S
- C2S
- C3A
- C4AF
- Tricalcium silicate (Alite)
- Dicalcium silicate (Belite)
- Tricalcium aluminate
- Calcium aluminoferrite
What is the clinker mixed with and finely ground to make the cement?
It is mixed with a few % of calcium sulfate (e.g. gypsum)
In the reaction of cement with water, what are the hydration products ?
- C-S-H (calcium silicate hydrate)
- CH (calcium hydroxide)
- AFt and AFm (calcium sulfo- ferri- aluminate hydrates)
Describe the reaction of cement with water
E.g. which reactions are fast/slow
What are the two most important clinker components?
- Alite (impure tricalcium silicate, C3S)
- Aluminate (tricalcium aluminate, C3A)
Describe the Alite reaction equation
For neat Portland cement (ie. no pozzolanic additions), what does x and y approximate to?
x = 1.7
y=4
Describe the Tricalcium aluminate (‘aluminate’) reaction
What products are formed?
Ettringite - AFt
Monosulfate - AFm
What is this equation?
The hydration reaction for C3S
Describe the process of using the hydration reaction (e.g. for C3S, what useful information can be generated from the reaction)
- calculate the molecular masses, for each phase
- using the tables, now have the mass per mole and the density
- this can be used to calculate the volumes of reactants and products
- can determine the overall chemical shrinkage/expansion, and change in the volume of solids
What do the dashes in C-S-H represent?
That there is variable chemical composition
What is the difference between crystalline and amorphous structure?
Crystalline - atoms are in regular repeating patterns in 3-D space
Amorphous - irregular patterns
