NDA Chemistry · Industrial and Applied Chemistry

Cement, Glass and Building Materials

What glass and Portland cement are actually made of — their raw materials, the chemical compounds inside set cement, and the property statements (glass is a supercooled liquid; pyrex beats soda glass) the bank loves to test.

All Industrial and Applied Chemistry notes NDA Chemistry strategy

Why this matters

Six PYQs, mostly EASY/MODERATE. The bank asks the raw materials of glass or cement, the compounds present in set cement, or a 'which statement about glass is NOT correct' trap. Two reliable facts win most marks: glass is an amorphous (non-crystalline) supercooled liquid, and Portland cement is made from lime, silica and alumina.

Concept 1 of 2

Glass — nature and raw materials

Intuition

Glass is a non-crystalline solid — a supercooled liquid with no fixed melting point. It is made from sand (silica), soda and limestone. The bank tests both its physical nature and its ingredient list.

Definition

The glass facts the bank tests:

Glass is an amorphous (non-crystalline) solid — often described as a supercooled liquid; it has no definite melting point.
Raw materials: silica sand (SiO₂) — the source of silica, soda ash (Na₂CO₃), limestone (CaCO₃), and borax for borosilicate glass.
Gypsum is NOT a glass raw material (it belongs to cement/plaster).
Pyrex (borosilicate) glass contains boron oxide, making it harder and more heat-resistant than ordinary soda glass.

Aspect	Glass fact	Note
Physical nature	Amorphous, non-crystalline solid	Supercooled liquid; no definite melting point Glass is a non-crystalline amorphous solid — a supercooled liquid.
Source of silica	Sand (SiO₂)	The silica-providing raw material Sand is the source of silica in glass-making.
Other raw materials	Soda ash, limestone, borax	Borax → borosilicate (pyrex)
NOT a glass material	Gypsum (CaSO₄·2H₂O)	Belongs to cement/plaster, not glass Gypsum is the trap option — it is NOT used in making glass.
Pyrex vs soda glass	Pyrex is harder	Pyrex has boron oxide; heat-resistant 'Soda glass is harder than pyrex' is FALSE — pyrex (borosilicate) is the harder, more heat-resistant one.

Practice this conceptself-check · 4 quick reps

Try it yourself

Of soda, alumina, borax and gypsum, which one is NOT used as a raw material in glass-making?

Practice — Level 1 (4 reps)

Quick reps to lock in the method. Try each, then check.

1.
Glass is which kind of solid — crystalline or amorphous?
2.
What is the source of silica in glass-making?
3.
Which of soda, alumina, borax, gypsum is NOT a glass raw material?
4.
Is soda glass harder than pyrex glass?

From the bank · past-year question

Example 1Industrial and Applied ChemistryEASY

Glass is a

[Q61 · Apr · 2017]

Pyrex is harder than soda glass

'Soda glass is harder than pyrex glass' is NOT correct. Pyrex is borosilicate glass — it contains boron oxide, which makes it harder and far more heat-resistant than ordinary soda glass.

Gypsum is the glass trap

When asked which is NOT a glass raw material, gypsum is the answer. Soda, limestone, sand and borax all go into glass; gypsum belongs to cement/plaster.

Drill 3 more on glass — nature and raw materials

Concept 2 of 2

Portland cement — raw materials and compounds

Intuition

Portland cement is made from lime, silica and alumina, and when set it contains a fixed set of calcium silicate and aluminate compounds. The bank asks both the raw-material list and 'which compound is NOT present in cement'.

Definition

The cement facts the bank tests:

Essential raw materials / constituents: lime (CaO), silica (SiO₂) and alumina (Al₂O₃) (plus a little iron oxide).
Compounds present in set Portland cement:
3CaO·SiO₂ (tricalcium silicate, *alite*)
2CaO·SiO₂ (dicalcium silicate, *belite*)
3CaO·Al₂O₃ (tricalcium aluminate)
4CaO·Al₂O₃·Fe₂O₃ (tetracalcium aluminoferrite)
4CaO·SiO₂ is NOT a cement compound — the silicates are only the 3:1 and 2:1 ratios.
Gypsum is added in a small amount to regulate the setting time.

Aspect	Cement fact	Note
Raw materials	Lime, silica, alumina	+ a little iron oxide Essential constituents of Portland cement: silica, alumina, lime.
Alite	3CaO·SiO₂	Tricalcium silicate
Belite	2CaO·SiO₂	Dicalcium silicate
Aluminate	3CaO·Al₂O₃	Tricalcium aluminate
NOT in cement	4CaO·SiO₂	No such silicate; only 3:1 and 2:1 4CaO·SiO₂ is the trap — it is NOT a standard cement compound.
Setting regulator	Gypsum (small amount)	Slows the setting time

Practice this conceptself-check · 4 quick reps

Try it yourself

Which of 2CaO·SiO₂, 3CaO·SiO₂, 4CaO·SiO₂, 3CaO·Al₂O₃ is NOT present in set Portland cement?

Practice — Level 1 (4 reps)

Quick reps to lock in the method. Try each, then check.

1.
Name the three essential raw materials of Portland cement.
2.
Which silicate compound is NOT present in cement: 2CaO·SiO₂, 3CaO·SiO₂ or 4CaO·SiO₂?
3.
Why is a little gypsum added to cement?
4.
What is the chemical name of 3CaO·SiO₂ in cement?

From the bank · past-year question

Example 2Industrial and Applied ChemistryMODERATE

Which one of the following is NOT present in cement ?

[Q99 · Sep · 2025]

4CaO·SiO₂ does not exist in cement

Cement's calcium silicates are the 3:1 (3CaO·SiO₂) and 2:1 (2CaO·SiO₂) ratios only. A '4CaO·SiO₂' option is fabricated — it is the 'which is NOT present' answer.

Drill 1 more on portland cement — raw materials and compounds

Summary — formulas & gotchas at a glance

A revision cheat-sheet for the formulas and gotchas above. Click any concept name to jump back to its full explanation.

Reference tables (2)

Glass — nature and raw materials5 rows

Aspect	Glass fact	Note
Physical nature	Amorphous, non-crystalline solid	Supercooled liquid; no definite melting point Glass is a non-crystalline amorphous solid — a supercooled liquid.
Source of silica	Sand (SiO₂)	The silica-providing raw material Sand is the source of silica in glass-making.
Other raw materials	Soda ash, limestone, borax	Borax → borosilicate (pyrex)
NOT a glass material	Gypsum (CaSO₄·2H₂O)	Belongs to cement/plaster, not glass Gypsum is the trap option — it is NOT used in making glass.
Pyrex vs soda glass	Pyrex is harder	Pyrex has boron oxide; heat-resistant 'Soda glass is harder than pyrex' is FALSE — pyrex (borosilicate) is the harder, more heat-resistant one.

Portland cement — raw materials and compounds6 rows

Aspect	Cement fact	Note
Raw materials	Lime, silica, alumina	+ a little iron oxide Essential constituents of Portland cement: silica, alumina, lime.
Alite	3CaO·SiO₂	Tricalcium silicate
Belite	2CaO·SiO₂	Dicalcium silicate
Aluminate	3CaO·Al₂O₃	Tricalcium aluminate
NOT in cement	4CaO·SiO₂	No such silicate; only 3:1 and 2:1 4CaO·SiO₂ is the trap — it is NOT a standard cement compound.
Setting regulator	Gypsum (small amount)	Slows the setting time

Watch out for (3)

Pyrex is harder than soda glass
→ Glass — nature and raw materials
Gypsum is the glass trap
→ Glass — nature and raw materials
4CaO·SiO₂ does not exist in cement
→ Portland cement — raw materials and compounds

Mastery check — 4 interleaved questions

Try each one before clicking. Questions are interleaved across the concepts above, not grouped — interleaving sharpens transfer.

Example 1Industrial and Applied ChemistryEASY

For manufacturing of glass, which among the following is used as a source of silica?

[Q111 · Apr · 2023]

Example 2Industrial and Applied ChemistryEASY

Which among the following are essential constituents of Portland cement ?

[Q65 · Apr · 2024]

Example 3Industrial and Applied ChemistryMODERATE

Which one of the following is not used as a raw material in the manufacture of glass ?

[Q58 · Apr · 2021]

Example 4Industrial and Applied ChemistryMODERATE

Which one of the following statements about glass is

\textbf{\text{not}}

correct?

[Q57 · Sep · 2019]

Drill every past-year question on this subtopic

6 questions from the bank — paginated, with cart and Word-export support.

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