The document discusses the major compounds found in cement clinker and their abbreviations. The four major compounds are tricalcium silicate (C3S), dicalcium silicate (C2S), tricalcium aluminate (C3A), and tetracalcium aluminoferrite (C4AF). C3S contributes to early strength while C2S defines later strength. C3A reacts immediately with water but causes flash setting without gypsum. Hydration of the cement forms calcium silicate hydrate (C-S-H) and calcium hydroxide, which are the primary products that give cement its strength.

1. Compound Composition of Clinker /
Cement
• Four major compound Formed from the Oxides under high
temperature in the kiln
• Name (Oxide Notation ) – Shorthand
• Tricalcium Silicate (3 CaO. SiO2) – C3S
• Dicalcium Silicate (2 CaO. SiO2) – C2S
• Tricalcium aluminate (3 CaO.Al2O3) – C3A
• Tetracalcium aluminoferrite (4 CaO . Al2O3.Fe2O3) – C4AF

2. Summary of Cement Compounds
Name Formula Shorthand Weight %
Tricalcium Silicate
(Alite)
3CaO.SiO2 C3S 55-60
Dicalcium Silicate
(Belite)
2Cao.SiO2 C2S 15-20
Tricalium Aluminate 3 Cao. Al2O3 C3A 5-10
Tetracalcium
Aluminoferrite
4 Cao.Al2O3.Fe2O3 C4AF 5-8
Gypsum CaSO4.2H2O CSH2 2-6

3. Contribution of Compounds to
Strength
• C3S Contributes to high early strength - to make
high early strength concrete , higher C3S
Proposortions needed.
• C2S contributes to later age strength defines the long
term strength
• C3A reacts immediately with water - defines set
• In the absence of gypsum , C3A causes flash set

4. Cement and Hydration of Portland
Cement Schematically represent

5. Calcium Silicate Hydrate
The course of reaction of C3S and C2S with water,
calcium silicate hydrate. Abbreviated C-S-H and
calcium Hydroxide , Ca(OH)2 are formed .
Calcium Silicate hydrate are the most important
products.
Chemical Equation for gel Formulation
2(3 CaO.SiO2) + 6H2O → 3CaO.2SiO2.3H2O +
3Ca(OH)2
2C2S + 4 H → C3S2H3 + Ca (OH)2