Chemistry · Chapter 22
Study notes aligned to the official NEB syllabus.
Cement is a finely powdered material that, when mixed with water, sets and hardens into a strong, adhesive mass capable of binding other building materials (sand, gravel, bricks) together. It remains stable in water and resists chemical attack once set, which is why it is the basic binding material of modern construction (concrete, mortar, plaster).
A typical Portland cement clinker has approximately the following oxide composition by mass: $CaO$ 50-60%, $SiO_2$ 20-25%, $Al_2O_3$ 5-10%, $Fe_2O_3$ 1-2%, $MgO$ 2-3%, with small amounts of $Na_2O$/$K_2O$ and $SO_3$.
| Category | Source materials | Supplies |
|---|---|---|
| Calcareous materials | Limestone, cement rock, chalk | $CaO$ |
| Argillaceous materials | Clay, shale, blast furnace slag | $SiO_2$, $Al_2O_3$, $Fe_2O_3$ |
| Gypsum | $CaSO_4\cdot 2H_2O$ | $SO_3$, added at the final grinding stage to control setting time |
Cement is a finely powdered material that, when mixed with water, sets and hardens into a strong, adhesive mass capable of binding other building materials (sand, gravel, bricks) together. It remains stable in water and resists chemical attack once set, which is why it is the basic binding material of modern construction (concrete, mortar, plaster).
A typical Portland cement clinker has approximately the following oxide composition by mass: 50-60%, 20-25%, 5-10%, 1-2%, 2-3%, with small amounts of / and .
| Category | Source materials | Supplies |
|---|---|---|
| Calcareous materials | Limestone, cement rock, chalk | |
| Argillaceous materials | Clay, shale, blast furnace slag | , , |
| Gypsum | , added at the final grinding stage to control setting time |