Cement – Complete Study Notes for GATE, ESE & SSC JE

🏗 Cement 🔥 Day 1

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Cement — Complete Study Notes

10 chapters · GATE, ESE (IES), SSC JE, State PSC, RRB JE

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Cement is the single most critical topic in Building Materials for GATE Civil, ESE (IES) and SSC JE. This chapter covers everything — from raw materials and manufacturing through hydration chemistry, Bogue's compounds, physical & chemical tests, all types of special cements, admixtures, IS codes and exam-focused numerical values.

Learning Objectives

After studying this chapter you will be able to:

Identify the two raw-material groups of cement and compute the Lime Saturation Factor, Silica Modulus and Alumina Modulus from oxide analysis
Describe the dry and wet manufacturing processes and the temperature zones inside a rotary kiln
Calculate Bogue's compounds (C₃S, C₂S, C₃A, C₄AF) from oxide percentages and explain how each compound governs strength, setting and heat of hydration
Explain the mechanism and stages of hydration, and distinguish setting from hardening and flash set from false set
Recall the IS 4031 test apparatus, procedure and acceptance limits for fineness, consistency, setting time, soundness and compressive strength
Select the correct type of cement (OPC/RHPC/LHPC/SRPC/PPC/PBFSC/HAC/SSC/etc.) for a given site condition, and cite the governing IS code
Classify chemical and mineral admixtures by mechanism and know their typical dosage and effect

Exam Relevance

ESE★★★★★

GATE★★★★★

SSC JE★★★★★

State PSC★★★★☆

💡 Cement is tested in nearly every civil engineering competitive exam — Bogue compound calculation, IS-code acceptance limits, and "which cement for which situation" are recurring MCQ/NAT question types.

Concept Map

Raw Materials (Calcareous + Argillaceous)

↓

Manufacture (Dry / Wet Process → Rotary Kiln → Clinker)

↓

Chemical Composition → Bogue's Compounds (C₃S, C₂S, C₃A, C₄AF)

↓

Hydration (Setting → Hardening)

↓

Physical Tests (IS 4031) — fineness, consistency, setting time, soundness, strength

Chemical Requirements (IS 269) — LSF, MgO, SO₃, LOI, alkalis

↓

Types & Special Cements (OPC/RHPC/SRPC/PPC/HAC/SSC/…)

↓

Admixtures (Chemical + Mineral)

Where This Fits

Prerequisite: the Building Materials Overview introduces the general testing framework (water-cement ratio, IS-code acceptance limits) this chapter goes deep on.

Leads into: cement properties feed directly into Concrete Technology and Design of RCC/PCC Structures.

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Ch 1 · Raw Materials of Cement

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Two Principal Groups

Group	Chemical Nature	Sources	Provides
Calcareous materials	$CaCO_{3}$-rich	Limestone, chalk, marl, calcareous shale, sea shells	CaO (lime) — 60–67% of cement
Argillaceous materials	$SiO_{2}$, $Al_{2}O_{3}$, $Fe_{2}O_{3}$-rich	Clay, shale, laterite, blast furnace slag	Silica, alumina, iron oxide

Approximate Oxide Composition of OPC

Oxide	Symbol	% Range	Effect if Excess
Lime	CaO	60–67%	Unsoundness (free CaO), expansion
Silica	$SiO_{2}$	17–25%	Slow-setting, weak early strength
Alumina	$Al_{2}O_{3}$	3–8%	Quick setting, low durability
Iron oxide	$Fe_{2}O_{3}$	0.5–6%	Dark colour; flux during burning
Magnesia	MgO	< 4%	Delayed unsoundness (periclase)
Sulphur trioxide	$SO_{3}$	< 2.5%	Expansion, sulphate attack
Alkalis	$Na_{2}O + K_{2}O$	< 1%	Alkali–silica reaction (ASR)
Loss on Ignition	LOI	< 4%	Indicates pre-hydration / adulteration

⚠ Free lime (f-CaO) and free magnesia (periclase, f-MgO) are the main causes of unsoundness — they expand after setting and cause cracking. Detected by the Le Chatelier test (CaO) and Autoclave test (MgO).

The Three Raw-Mix Moduli

Three moduli control clinker burnability and quality — LSF (lime content), SM (ease of burning), and AM (which aluminate phase forms). See the Formulas tab for the equations.

LSF > 1.02 → excess free CaO → unsoundness; LSF < 0.66 → insufficient clinker formation → weak cement
High SM → hard to burn, slow setting; Low SM → easy to burn, but poor strength
AM > 0.637 → $C_3A$ forms (normal cement); AM < 0.637 → no $C_3A$; $C_4AF$ dominates (sulphate-resistant cement)

💡 GATE/ESE Tip: LSF, SM and AM are the three moduli used in raw-mix design. Questions on these appear regularly in GATE as numerical-answer-type (NAT) problems — always identify which oxide % is being substituted before calculating.

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Ch 1 · Raw-Mix Moduli — Formulas

Lime Saturation Factor

$$ LSF = \frac{CaO}{2.8\,SiO_{2} + 1.2\,Al_{2}O_{3} + 0.65\,Fe_{2}O_{3}} $$

Ideal range 0.66–1.02; IS 269 limit 0.80–1.02

—

Silica Modulus

$$ SM = \frac{SiO_{2}}{Al_{2}O_{3} + Fe_{2}O_{3}} $$

Typical value 1.7–4.0

—

Alumina Modulus

$$ AM = \frac{Al_{2}O_{3}}{Fe_{2}O_{3}} $$

Typical 1–4; > 10 for white cement

—

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Ch 1 · Solved Examples

GATE CE / ESE level

A clinker's oxide analysis gives CaO = 65%, $SiO_2$ = 21%, $Al_2O_3$ = 5.5%, $Fe_2O_3$ = 3%. Compute the LSF, SM and AM, and comment on whether the raw mix is within the IS 269 LSF range.

Approach hint

Substitute directly into the three moduli formulas; compare LSF against the IS 269 range 0.80–1.02.

$LSF = \dfrac{65}{2.8(21) + 1.2(5.5) + 0.65(3)} = \dfrac{65}{58.8+6.6+1.95} = \dfrac{65}{67.35} \approx 0.965$
$SM = \dfrac{21}{5.5+3} = \dfrac{21}{8.5} \approx 2.47$
$AM = \dfrac{5.5}{3} \approx 1.83$
LSF ≈ 0.965 lies within 0.80–1.02 → raw mix is acceptable; AM > 0.637 → $C_3A$ will form normally

✓ LSF ≈ 0.965 (within IS 269 range), SM ≈ 2.47 (typical), AM ≈ 1.83 (normal cement, $C_3A$ forms)

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Ch 1 · Quick Quiz

3 questions · tap an option to reveal answer

Question 1

Which raw material group supplies most of the CaO in cement?

Calcareous materials (limestone, chalk) are $CaCO_3$-rich and supply 60–67% CaO ✓

Question 2

If AM < 0.637, which compound dominates the aluminate phase?

Below AM = 0.637 there isn't enough alumina relative to iron oxide to form $C_3A$; all the aluminate reports as $C_4AF$ instead — this is exactly how Sulphate Resisting Cement is engineered ✓

Question 3

An LSF value greater than 1.02 indicates:

LSF above the IS 269 range (0.80–1.02) means more lime than the silicates/aluminates can combine with, leaving free CaO that causes unsoundness ✓

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Ch 2 · Manufacture of Portland Cement

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Two Main Processes

Feature	Dry Process	Wet Process
Raw material moisture	Low (< 1%)	High (30–40%)
Grinding	Dry grinding in ball mills	Wet grinding; slurry formed
Raw mix form	Dry powder (raw meal)	Slurry (33–40% water)
Kiln length	Shorter (50–90 m)	Longer (150–200 m)
Heat consumption	Lower (3.5 GJ/t)	Higher (5.0–6.0 GJ/t)
Capital cost	Higher (pre-heater)	Lower initial cost
Product homogeneity	Lower (requires blending)	Better (slurry mixing)
Current use	Predominant worldwide	Declining; used where raw materials are wet

Steps in Dry Process (Modern)

Quarrying & crushing: Limestone and clay crushed to <25 mm
Pre-blending & storage: Stacker-reclaimer beds
Proportioning & grinding (Raw Mill): Ball mill or vertical roller mill; raw meal to ~90 µm
Blending silos: Homogenisation of raw meal
Pre-heater tower (cyclones): 4–6 stage; heat exchange raises meal to ~800°C
Pre-calciner: 60–95% decarbonation; $CaCO_3 \rightarrow CaO + CO_2$
Rotary kiln (burning zone): Peak temperature ~1450°C; clinker formation
Clinker cooler: Rapid cooling to <100°C (grate cooler)
Cement grinding (Finish Mill): Clinker + gypsum (3–5%) + any additions; ground to fineness
Storage & dispatch: Silos then bags or bulk tankers

Reactions in the Rotary Kiln (Temperature Zones)

Temperature (°C)	Zone	Reaction
100–300	Drying	Evaporation of free moisture
300–600	Pre-heating	Removal of absorbed water; clay dehydration
600–900	Calcination	$CaCO_3 \rightarrow CaO + CO_2$ (endothermic)
900–1200	Solid-state reaction	$C_2S$ formation; beginnings of $C_3A$ & $C_4AF$
1250–1280	Exothermic	Liquid phase appears; rapid formation of $C_3S$ from $C_2S$ + CaO
1350–1450	Burning / Clinkering	$C_3S$ fully formed; peak clinker temperature; nodule formation
Cooling	Clinker cooling	Rapid cooling preserves $C_3S$; slow cooling causes $C_3S \rightarrow C_2S$ + free CaO (belite reversion)

⚠ Slow cooling of clinker causes $C_3S$ to revert to $C_2S$ + free CaO → reduced strength and unsoundness. Therefore rapid cooling is essential.

Clinker Composition

Clinker nodules: 3–25 mm diameter; dark grey
Free lime content in clinker must be < 1.5%
Gypsum addition: controls setting time by reacting with $C_3A$ to form Ettringite
Over-addition of gypsum: > 3.5% $SO_3$ in cement causes false set and expansion

💡 GATE Tip: The temperatures 1450°C (clinkering), 900°C (calcination) and the reaction $CaCO_3 \rightarrow CaO + CO_2$ are frequently tested in MCQ format.

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Ch 2 · Manufacturing — Key Numbers

Clinkering (burning zone) temperature

1350 – 1450°C

Peak temperature where $C_3S$ fully forms

°C

Calcination reaction temperature

$$ CaCO_3 \xrightarrow{\sim 900°C} CaO + CO_2 $$

Endothermic decarbonation, the largest single heat demand in the process

°C

Heat consumption

Dry: 3.5 GJ/t | Wet: 5.0–6.0 GJ/t

Wet process needs extra heat to evaporate 30–40% slurry water

GJ/tonne

Gypsum addition

3 – 5% by mass at finish mill

Controls $C_3A$ reactivity via Ettringite; >3.5% $SO_3$ causes false set

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Ch 2 · Solved Examples

GATE CE / ESE level

A cement plant producing 1000 tonnes/day switches from the wet process (5.5 GJ/t) to the dry process (3.5 GJ/t). Find the daily heat energy saved.

Approach hint

Multiply the heat-consumption difference per tonne by the daily production.

Saving per tonne = $5.5 - 3.5 = 2.0$ GJ/t
Daily saving = $2.0 \times 1000 = 2000$ GJ/day

✓ 2000 GJ/day saved — illustrates why the dry process dominates modern cement manufacture

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Ch 2 · Diagrams

Click any diagram to zoom

Temperature rises progressively along the kiln from feed end (drying) to burning zone (1450°C clinkering)

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Ch 2 · Quick Quiz

3 questions · tap an option to reveal answer

Question 1

The peak clinkering temperature inside a rotary kiln is approximately:

1350–1450°C is the burning/clinkering zone where $C_3S$ fully forms ✓

Question 2

Slow cooling of clinker after burning causes:

Slow cooling allows belite reversion — $C_3S$ breaks back down to $C_2S$ + free CaO, reducing strength and causing unsoundness ✓

Question 3

Compared to the wet process, the dry process has:

Dry process needs no water evaporation (3.5 vs 5.0–6.0 GJ/t) but the pre-heater tower raises capital cost; it also uses a shorter kiln ✓

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Ch 3 · Chemical Composition & Bogue's Compounds

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Bogue's Compounds — Complete Table

Compound	Abbreviation	Full Chemical Name	Formula	% in OPC
Alite	$C_3S$	Tricalcium Silicate	3CaO·$SiO_2$	40–50%
Belite	$C_2S$	Dicalcium Silicate	2CaO·$SiO_2$	25–35%
Celite (aluminate phase)	$C_3A$	Tricalcium Aluminate	3CaO·$Al_2O_3$	5–12%
Ferrite phase	$C_4AF$	Tetracalcium Aluminoferrite	4CaO·$Al_2O_3$·$Fe_2O_3$	8–14%

⚠ GATE PYQ format: Given oxide % → find Bogue compound %. These are direct substitution problems. Always use the Bogue formulae in the order $C_3S \rightarrow C_2S \rightarrow C_3A \rightarrow C_4AF$.

Properties of Each Compound — Comparison

Property	$C_3S$	$C_2S$	$C_3A$	$C_4AF$
Rate of hydration	Moderate–fast	Slow	Very fast	Moderate
Early strength (1–7 days)	High	Low	Very high (minor)	Low
Long-term strength (28 d+)	High	High	Low	Low
Heat of hydration (J/g)	~502	~260	~867	~419
Resistance to sulphate	Moderate	High	Very low	Moderate–high
Colour contribution	None (white)	None (white)	None (white)	Grey/brown
Role of gypsum	Delays set slightly	Minor	Critical (prevents flash set)	Minor

Strength Development (% of 28-day strength)

Age	$C_3S$	$C_2S$	$C_3A$	$C_4AF$
1 day	~46%	~6%	~53%	~30%
7 days	~72%	~20%	~92%	~60%
28 days	100%	100%	100%	100%
1 year	~110%	~160%	~105%	~106%

💡 $C_2S$ continues gaining strength for years beyond 28 days — 1-year strength can be 160% of 28-day strength. This is exploited in Low Heat and Portland Pozzolana Cements.

Heat of Hydration (HOH) Order

$C_3A > C_3S > C_4AF > C_2S$ (867 > 502 > 419 > 260 J/g)

Total HOH of OPC at 28 days ≈ 375–525 J/g
Low Heat cement target: ≤ 272 kJ/kg at 7 days; ≤ 314 kJ/kg at 28 days

Cement Notation (Abbreviated Oxide Notation)

Oxide	Full formula	Notation
Calcium oxide (lime)	CaO	C
Silicon dioxide (silica)	$SiO_2$	S
Aluminium oxide (alumina)	$Al_2O_3$	A
Iron oxide	$Fe_2O_3$	F
Water	$H_2O$	H
Sulphur trioxide	$SO_3$	S̄

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Ch 3 · Bogue Calculation Formulae

From oxide analysis (all oxide % by mass)

$C_3S$ (Tricalcium Silicate)

$$ C_3S = 4.071\,CaO - 7.600\,SiO_2 - 6.718\,Al_2O_3 - 1.430\,Fe_2O_3 - 2.852\,SO_3 $$

Calculate first — all other formulas may depend on it

$C_2S$ (Dicalcium Silicate)

$$ C_2S = 2.867\,SiO_2 - 0.7544\,C_3S $$

Uses the $C_3S$ value computed above

$C_3A$ (Tricalcium Aluminate)

$$ C_3A = 2.650\,Al_2O_3 - 1.692\,Fe_2O_3 $$

Independent of $C_3S$/$C_2S$

$C_4AF$ (Tetracalcium Aluminoferrite)

$$ C_4AF = 3.043\,Fe_2O_3 $$

Simplest of the four — direct proportion to $Fe_2O_3$

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Ch 3 · Solved Examples

GATE CE / ESE level

Oxide analysis of a cement clinker: CaO = 64%, $SiO_2$ = 21%, $Al_2O_3$ = 5%, $Fe_2O_3$ = 3%, $SO_3$ = 2%. Compute the Bogue compounds $C_3S$, $C_2S$, $C_3A$ and $C_4AF$.

Approach hint

Apply the four Bogue formulas in order — $C_3S$ first, then $C_2S$ (which needs $C_3S$), then $C_3A$ and $C_4AF$ independently.

$C_3S = 4.071(64) - 7.600(21) - 6.718(5) - 1.430(3) - 2.852(2)$
$= 260.5 - 159.6 - 33.6 - 4.29 - 5.70 = 57.3\%$
$C_2S = 2.867(21) - 0.7544(57.3) = 60.2 - 43.2 = 17.0\%$
$C_3A = 2.650(5) - 1.692(3) = 13.25 - 5.08 = 8.2\%$
$C_4AF = 3.043(3) = 9.1\%$

✓ $C_3S \approx 57.3\%$, $C_2S \approx 17.0\%$, $C_3A \approx 8.2\%$, $C_4AF \approx 9.1\%$ — sum ≈ 91.6% of clinker mass (remainder is free lime, MgO, alkalis, minor oxides)

Using the compound percentages from Example 1, estimate the total heat of hydration of this cement at 28 days (use HOH values $C_3S$=502, $C_2S$=260, $C_3A$=867, $C_4AF$=419 J/g).

Approach hint

Weighted sum: multiply each compound's mass fraction by its HOH value and add.

$C_3S$: $0.573 \times 502 = 287.6$ J/g
$C_2S$: $0.170 \times 260 = 44.2$ J/g
$C_3A$: $0.082 \times 867 = 71.1$ J/g
$C_4AF$: $0.091 \times 419 = 38.1$ J/g
Total ≈ $287.6+44.2+71.1+38.1 = 441$ J/g

✓ Total HOH ≈ 441 J/g, within the typical OPC range of 375–525 J/g

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Ch 3 · Diagrams

Click any diagram to zoom

Bogue compound proportions in a typical OPC clinker — C₃S and C₂S (the calcium silicates) make up ~70–75% of the mass

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Ch 3 · Quick Quiz

3 questions · tap an option to reveal answer

Question 1

Which Bogue compound has the highest heat of hydration?

$C_3A$ has the highest heat of hydration (~867 J/g) — that's why low-$C_3A$ cements are used for mass concrete ✓

Question 2

Which compound continues gaining strength the longest, reaching ~160% of 28-day strength at 1 year?

$C_2S$ hydrates slowly but keeps reacting for years — this long-term gain is exploited in Low Heat and Pozzolana cements ✓

Question 3

In the Bogue calculation order, which compound must be computed first?

$C_3S$ must be computed first because the $C_2S$ formula subtracts $0.7544 \times C_3S$ ✓

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Ch 4 · Hydration of Cement

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Definition & Mechanism

Hydration is the chemical reaction between cement compounds and water that produces binding products (C–S–H gel) and causes setting and hardening. The process involves both dissolution (ions dissolve from the clinker surface) and precipitation (products crystallise from solution).

Hydration Reactions (Complete)

Compound	Hydration Reaction	Products
$C_3S$ (Alite)	$2C_3S + 6H \rightarrow C_3S_2H_3 + 3Ca(OH)_2$	C–S–H gel + Portlandite
$C_2S$ (Belite)	$2C_2S + 4H \rightarrow C_3S_2H_3 + Ca(OH)_2$	C–S–H gel + less Portlandite
$C_3A$ (initial, with gypsum)	$C_3A + 3C\bar SH_2 + 26H \rightarrow C_6AS_3H_{32}$	Ettringite (AFt phase) — prevents flash set
$C_3A$ (after gypsum exhausted)	$2C_3A + C_6AS_3H_{32} + 4H \rightarrow 3C_4A\bar SH_{12}$	Monosulphate (AFm phase)
$C_4AF$	$C_4AF + 2Ca(OH)_2 + 10H \rightarrow C_6AFH_{12}$	Calcium aluminoferrite hydrate

💡 C–S–H gel (Calcium Silicate Hydrate) is the primary binding phase in hardened cement paste, constituting ~60–70% of the hydration products. $Ca(OH)_2$ (Portlandite) constitutes ~20–25%; it is responsible for the high pH of concrete (~12.5) that passivates steel reinforcement.

Stages of Hydration (Le Chatelier Stages)

Stage	Time	What Happens
Pre-induction / Initial	0–15 min	Rapid dissolution of $C_3A$; first ettringite forms; early heat release spike
Induction / Dormant	15 min–3 hrs	Slow reaction; cement remains workable; ion concentration builds
Acceleration	3–8 hrs	$C_3S$ hydration accelerates; C–S–H nucleates rapidly; initial set
Deceleration	8–24 hrs	Reaction slows as products form a diffusion barrier around grains; final set
Slow / Long-term	24 hrs onwards	Continued hydration; gradual pore refinement; strength development for months/years

Setting vs Hardening

Feature	Setting	Hardening
Definition	Loss of plasticity / stiffening of paste	Development of strength and rigidity
Time scale	Minutes to hours (IST & FST)	Hours to years (28-day strength and beyond)
Primarily due to	$C_3A$ hydration & Ettringite formation	$C_3S$ & $C_2S$ hydration (C–S–H gel formation)
Temperature effect	Higher temp → faster set	Higher temp → faster early strength but lower 28-day strength

Flash Set vs False Set

Feature	Flash Set	False Set
Cause	Rapid reaction of $C_3A$ with insufficient gypsum	Dehydration of gypsum ($CaSO_4 \cdot 2H_2O \rightarrow CaSO_4 \cdot \tfrac{1}{2}H_2O$) during hot grinding
Heat release	Significant heat	No significant heat
Remixing	Cannot be restored by remixing	Can be restored by vigorous remixing (re-dissolves $CaSO_4 \cdot \tfrac{1}{2}H_2O$)
Product	Ettringite (expansive)	Re-hydrated gypsum (no expansion)

Degree of Hydration (α) and Water Requirements

Theoretical minimum water for complete hydration: w/c ≈ 0.23
Practical minimum for full hydration: w/c ≈ 0.36 (includes gel water)
At w/c < 0.36, unhydrated cement grains remain permanently
Degree of hydration at 28 days for OPC with w/c = 0.50: ≈ 70%

Products of Hydration and Their Volume

Product	% Volume of Paste	Role
C–S–H gel	50–60%	Primary binding; strength
$Ca(OH)_2$ (Portlandite)	20–25%	High pH; passivation of steel
Ettringite / Monosulphate	15–20%	Early structure; sulphate reactant
Unreacted cement	Variable	Latent reservoir
Gel pores	Very fine	Intrinsic to C–S–H; ~3 nm
Capillary pores	Variable (reduces with hydration)	Main pathway for aggressive agents

⚠ Capillary porosity is the main factor controlling durability. It decreases as hydration proceeds (pore refinement). Low w/c + prolonged curing → minimal capillary porosity → high durability.

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Ch 4 · Hydration — Key Numbers

Theoretical min. w/c for complete hydration

w/c ≈ 0.23

Chemically-combined water only

—

Practical min. w/c for full hydration

w/c ≈ 0.36

Includes gel water; below this, unhydrated grains remain permanently

—

Degree of hydration at 28 days

α ≈ 70% (at w/c = 0.50)

Fraction of cement that has reacted

C–S–H gel content

50–60% of paste volume

Primary binding phase

💧

Ch 4 · Solved Examples

GATE CE / ESE level

A concrete mix uses w/c = 0.30. Will all the cement in this mix eventually hydrate fully, assuming ample moist curing? Explain.

Approach hint

Compare the given w/c against the practical minimum (~0.36) needed for full hydration, including gel water.

Practical minimum w/c for complete hydration ≈ 0.36 (accounts for gel water, not just chemically combined water)
Given w/c = 0.30 < 0.36
Even with unlimited curing, there isn't enough water physically available in the paste for every grain to hydrate

✓ No — at w/c = 0.30, some cement will remain permanently unhydrated (this is actually desirable for high-strength/low-permeability concrete, since unhydrated cores add strength without adding capillary porosity)

💧

Ch 4 · Diagrams

Click any diagram to zoom

Classic heat-evolution curve: an early spike (C₃A dissolution), a dormant period, then a large peak as C₃S accelerates (initial/final set occur here), followed by slow long-term reaction

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Ch 4 · Quick Quiz

3 questions · tap an option to reveal answer

Question 1

The primary binding phase of hardened cement paste is:

C–S–H gel makes up 50–60% of paste volume and is the main source of strength ✓

Question 2

Which of these can be restored by vigorous remixing?

False set is caused by dehydrated gypsum re-dissolving on remixing, with no lasting effect; flash set (Ettringite formation) cannot be reversed by remixing ✓

Question 3

Portlandite, $Ca(OH)_2$, is significant in concrete mainly because it:

Portlandite's high alkalinity forms a passive oxide film on embedded steel, protecting it from corrosion as long as the pH stays high ✓

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Ch 5 · Physical Properties & Laboratory Tests

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Summary of IS 4031 Tests

Test	IS 4031 Part	Apparatus / Method	What it Measures
Fineness (Sieving)	Part 1	90 µm IS sieve; 100 g sample	Coarse particle content
Fineness (Blaine)	Part 2	Air permeability apparatus	Specific surface area ($m^2$/kg)
Standard Consistency	Part 4	Vicat apparatus, 10 mm plunger	Water % for standard paste
Setting Time	Part 5	Vicat apparatus, 1 mm needle & annular needle	IST and FST
Soundness	Part 3	Le Chatelier mould; boiling	Expansion due to free CaO
Soundness (autoclave)	Part 3	Autoclave at 2 MPa, 3 hrs	Expansion due to free MgO
Compressive Strength	Part 6	70.6 mm mortar cubes; 1:3 cement:sand	Strength at 3, 7, 28 days
Heat of Hydration	Part 9	Adiabatic calorimeter	Total heat generated
Tensile Strength (briquette)	Part 8	Briquette mould; tensile testing	Tensile splitting strength

1. Fineness Test (IS 4031 Part 1 — Sieving)

100 g of cement sieved on 90 µm IS sieve for 15 minutes
Residue on sieve expressed as % of original mass
Acceptance: ≤ 10% residue for OPC
Finer cement → faster hydration, faster strength gain, higher heat of hydration

2. Fineness Test — Blaine's Air Permeability (IS 4031 Part 2)

Measures specific surface area (SSA) in $m^2$/kg
Principle: time for a fixed volume of air to flow through a compacted cement bed
OPC minimum: 225 $m^2$/kg; PPC: 300 $m^2$/kg; RHPC: 325 $m^2$/kg

3. Standard Consistency Test (IS 4031 Part 4)

Vicat apparatus with 10 mm diameter flat-end plunger, mass 300 g
Paste placed in Vicat mould; plunger released from surface level
Standard consistency = % water (P) when plunger penetrates to 5–7 mm from bottom
Typical P value: 26–33%
Note: subsequent tests use 0.85P for setting time and 0.78P for the Le Chatelier test

4. Setting Time Test (IS 4031 Part 5)

Parameter	Initial Setting Time (IST)	Final Setting Time (FST)
Needle used	1 mm square needle	Annular needle (1 mm pin inside 5 mm annular ring)
Criterion	Needle does NOT penetrate to within 5 mm of bottom plate	Annular ring leaves no impression; needle sinks 0.5 mm
Water content	0.85P (P = standard consistency)
Test conditions	27 ± 2°C; 65 ± 5% RH (IS 4031)

Cement Type	Min IST (min)	Max FST (min)
OPC 33, 43, 53	30	600
Rapid Hardening (RHPC)	30	600
Low Heat Cement	60	600
Sulphate Resistant (SRC)	30	600
High Alumina Cement	30	360
Masonry Cement	90	1440
Super Sulphated Cement	30	600

💡 Factors affecting setting time: ↑ Temperature → shorter IST and FST · ↑ Fineness → shorter IST and FST · ↑ w/c ratio → longer IST and FST · ↑ $C_3A$ content → shorter IST · ↑ Gypsum → longer IST · Retarders (sugar, lignosulfonates) → longer IST · Accelerators ($CaCl_2$) → shorter IST

5. Soundness Test (IS 4031 Part 3)

(a) Le Chatelier Method — detects free CaO expansion

Brass split-cylinder mould (30 mm dia, 30 mm high) with two steel indicators
Paste of 0.78P water content; sealed and kept 24 hrs at 27 ± 2°C
Initial reading ($d_1$) taken; then boiled for 3 hrs; cooled; final reading ($d_2$) taken
Expansion = $d_2 - d_1 \leq$ 10 mm for OPC (IS 269)
After re-testing: ≤ 5 mm

(b) Autoclave Method — detects free MgO expansion

Cement bar (25 mm × 25 mm × 285 mm) with neat cement paste
Cured 24 hrs at 27°C; then autoclaved at 2.0 MPa steam pressure for 3 hrs
Expansion ≤ 0.80% after autoclave treatment

6. Compressive Strength Test (IS 4031 Part 6)

Standard mortar cubes: 70.6 mm × 70.6 mm × 70.6 mm (face area = 50 $cm^2$)
Mix ratio: 1 cement : 3 standard Ennore sand; w/c = 0.40 (water = P/4 + 3%, where P = standard consistency)
Compacted in vibration table or hand compaction; demoulded after 24 hrs
Moist curing at 27 ± 2°C in water; tested at 3, 7 and 28 days
Loading rate: 35 N/$mm^2$/min; average of 3 cubes

Age	OPC 33 (MPa)	OPC 43 (MPa)	OPC 53 (MPa)
3 days	≥ 16	≥ 23	≥ 27
7 days	≥ 22	≥ 33	≥ 37
28 days	≥ 33	≥ 43	≥ 53

Physical Requirements Summary (OPC IS 269:2015)

Property	OPC 33	OPC 43	OPC 53
Specific gravity	3.10 – 3.15
Bulk density (loose)	~1440 kg/$m^3$
Normal consistency (P)	26 – 33%
Fineness (sieve, 90 µm)	≤ 10% residue
Fineness (Blaine)	≥ 225 $m^2$/kg	≥ 225 $m^2$/kg	≥ 225 $m^2$/kg
IST	≥ 30 min
FST	≤ 600 min
Soundness (Le Chatelier)	≤ 10 mm
Autoclave expansion	≤ 0.80%
Compressive strength 3 days	≥ 16 MPa	≥ 23 MPa	≥ 27 MPa
Compressive strength 7 days	≥ 22 MPa	≥ 33 MPa	≥ 37 MPa
Compressive strength 28 days	≥ 33 MPa	≥ 43 MPa	≥ 53 MPa

📏

Ch 5 · Test Formulas & Key Values

Blaine Specific Surface Area

$$ SSA = K\sqrt{t/\eta} $$

$t$ = air flow time, $\eta$ = air viscosity, $K$ = apparatus constant

m²/kg

Water for setting-time test

0.85 P

P = standard consistency water %

—

Water for Le Chatelier soundness test

0.78 P

P = standard consistency water %

—

Soundness expansion (Le Chatelier)

$$ Expansion = d_2 - d_1 \leq 10\text{ mm} $$

$d_1$ = initial indicator distance, $d_2$ = distance after 3 hr boiling

Water for compressive-strength mortar

$$ w = \tfrac{P}{4} + 3\% $$

1:3 cement:sand mortar cubes, w/c ≈ 0.40

Loading rate (compressive test)

35 N/mm²/min

Average of 3 mortar cubes

N/mm²/min

📏

Ch 5 · Solved Examples

GATE CE / ESE level

The standard consistency of a cement is found to be P = 30%. Find the water content to be used for (a) the setting time test and (b) the Le Chatelier soundness test.

Approach hint

Apply the standard multipliers directly: 0.85P for setting time, 0.78P for Le Chatelier.

Setting time water = $0.85 \times 30 = 25.5\%$
Le Chatelier water = $0.78 \times 30 = 23.4\%$

✓ Setting time test: 25.5% water; Le Chatelier test: 23.4% water

In a Le Chatelier soundness test, the initial indicator reading is 6.2 mm and the reading after 3 hours of boiling is 15.4 mm. Does this OPC sample pass the IS 269 soundness requirement?

Approach hint

Compute the expansion $d_2 - d_1$ and compare with the 10 mm limit for OPC.

Expansion = $15.4 - 6.2 = 9.2$ mm
IS 269 limit for OPC: ≤ 10 mm
$9.2$ mm $< 10$ mm

✓ Expansion = 9.2 mm — sample passes (just within the 10 mm limit)

📏

Ch 5 · Diagrams

Click any diagram to zoom

Vicat apparatus: a 1 mm needle is released onto the paste; initial set occurs when it stops penetrating within 5 mm of the base plate

📏

Ch 5 · Quick Quiz

3 questions · tap an option to reveal answer

Question 1

Standard consistency (P) is defined as the water % at which the Vicat plunger penetrates to:

The plunger must stop 5–7 mm from the bottom of the Vicat mould at standard consistency ✓

Question 2

A cement sample's fineness residue on the 90 µm sieve is 12%. As per IS 4031, this sample:

The IS 4031 sieve fineness limit for OPC is ≤ 10% residue; 12% exceeds it ✓

Question 3

The Autoclave soundness test specifically detects unsoundness caused by:

The Autoclave test (2 MPa steam, 3 hrs) detects delayed expansion from free magnesia; the Le Chatelier test detects free lime ✓

⚗️

Ch 6 · Chemical Properties & Requirements

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Chemical Requirements as per IS 269:2015

Chemical Property	Requirement (OPC)	Significance
Ratio ($Al_2O_3 / Fe_2O_3$)	≥ 0.66	Ensures $C_3A$ forms; important for setting & strength
Lime Saturation Factor (LSF)	0.80 – 1.02	Ensures no excess free CaO; proper clinker composition
Insoluble residue	≤ 2.0%	Indicates purity; siliceous adulterants detected
Magnesia (MgO)	≤ 6.0%	Excess MgO (periclase) causes delayed expansion
Sulphur trioxide ($SO_3$)	≤ 3.0% ($C_3A$ ≤ 5%); ≤ 3.5% ($C_3A >$ 5%)	Excess $SO_3$ causes expansion and cracking
Loss on Ignition (LOI)	≤ 5.0%	Indicates pre-hydration, adulteration or excess gypsum
Chloride ($Cl^-$)	≤ 0.05%	Excess chloride causes corrosion of steel reinforcement
Total alkalis ($Na_2O$ equivalent)	≤ 0.60% (low alkali cement)	High alkalis trigger alkali–silica reaction (ASR) with reactive aggregates

Sulphate Attack Mechanism

External $SO_4^{2-}$ from soil / groundwater reacts with the $C_3A$ hydration product
$Ca(OH)_2 + SO_4^{2-} \rightarrow CaSO_4$ (gypsum) → reacts with $C_3A$ → Ettringite (expansive)
$MgSO_4$ also attacks C–S–H gel directly → most destructive sulphate
Prevention: use SRC or GGBS cement; low w/c; dense concrete; membranes / coatings

Chloride Content in Concrete (IS 456:2000)

Type of Concrete	Max $Cl^-$ (% by mass of cement)
Prestressed concrete	0.10%
RCC in humid / aggressive environment	0.20%
RCC in normal environment	0.30%
Plain concrete (PCC)	0.60%

⚠ Common mistake: students often confuse sulphate attack (external $SO_4^{2-}$ reacting with $C_3A$) with ASR (internal reaction between reactive aggregate silica and cement alkalis). Both are expansive/cracking mechanisms but have completely different sources and defences (low-$C_3A$ SRC for sulphate attack; low-alkali cement or non-reactive aggregate for ASR).

⚗️

Ch 6 · Formulas

Sodium Oxide Equivalent (Alkali content)

$$ Na_2O_{eq} = Na_2O + 0.658\,K_2O $$

Low-alkali cement requires $Na_2O_{eq} \leq 0.60\%$

$Al_2O_3/Fe_2O_3$ minimum ratio

≥ 0.66

Below this, no $C_3A$ forms (sulphate-resistant behaviour)

—

⚗️

Ch 6 · Solved Examples

GATE CE / ESE level

A cement has $Na_2O$ = 0.25% and $K_2O$ = 0.40%. Is it a low-alkali cement as per IS 269?

Approach hint

Compute $Na_2O_{eq}$ and compare with the 0.60% low-alkali limit.

$Na_2O_{eq} = 0.25 + 0.658(0.40) = 0.25 + 0.263 = 0.513\%$
$0.513\% < 0.60\%$

✓ $Na_2O_{eq} \approx 0.51\%$ — qualifies as low-alkali cement, safe against ASR with reactive aggregates

⚗️

Ch 6 · Diagrams

Click any diagram to zoom

Sulphate attack cycle: external sulphate combines with Portlandite to form gypsum, which then reacts with C₃A to produce expansive Ettringite

⚗️

Ch 6 · Quick Quiz

3 questions · tap an option to reveal answer

Question 1

Which sulphate compound attacks C–S–H gel directly, making it the most destructive form of sulphate attack?

Magnesium sulphate attacks the C–S–H gel itself (not just the aluminate phase), making it the most severe form of sulphate attack ✓

Question 2

The maximum permissible chloride content (by mass of cement) for prestressed concrete is:

Prestressed concrete has the strictest limit (0.10%) because chloride-induced corrosion of highly-stressed tendons is especially dangerous ✓

Question 3

Low-alkali cement is defined by IS 269 as having $Na_2O_{eq}$:

$Na_2O_{eq} \leq 0.60\%$ qualifies as low-alkali cement, which is required when using potentially reactive aggregates to prevent ASR ✓

🏗

Ch 7 · Types of Portland Cement

Properties & IS Codes

○ Not Started

Ordinary Portland Cement (OPC)

Grade	IS Code	28-day Strength	Application
OPC 33	IS 269:2015	≥ 33 MPa	Plastering, masonry mortar, less critical structures
OPC 43	IS 8112:2013	≥ 43 MPa	General RCC, precast, pre-stressed (mild exposure)
OPC 53	IS 12269:2013	≥ 53 MPa	High-performance RCC, bridges, high-rise (preferred)

Other Portland Cement Variants

Rapid Hardening Portland Cement (RHPC)

IS Code: IS 8041:1990
Key change: Higher $C_3S$ content (up to 70%) and finer grinding (Blaine ≥ 325 $m^2$/kg)
Strength at 3 days ≈ 28-day strength of OPC 33
Uses: Road / pavement repair, emergency works, prefabrication, cold weather concreting
Higher heat of hydration → not suitable for mass concrete

Low Heat Portland Cement (LHPC)

IS Code: IS 12600:1989
Composition: Low $C_3S$ (max 35%) & low $C_3A$ (max 6%); High $C_2S$ (min 40%)
Heat of hydration: ≤ 272 kJ/kg at 7 days; ≤ 314 kJ/kg at 28 days
Setting: IST ≥ 60 min (slower)
Uses: Mass concrete — dams, raft foundations, large piers, thick retaining walls
Slower strength gain; long-term strength ultimately same as OPC

Sulphate Resisting Portland Cement (SRPC)

IS Code: IS 12330:1988
Composition: Very low $C_3A$ ≤ 5%; $C_3A + C_4AF$ ≤ 25%
When $Al_2O_3/Fe_2O_3$ ratio ≈ 0.64 → no $C_3A$ forms; all aluminate present as $C_4AF$
Uses: Foundations in sulphate-bearing soils, marine structures, sewers, coastal construction
Slightly lower early strength; grey colour; somewhat less workable

Portland Pozzolana Cement (PPC)

IS Code: IS 1489:1991 (Part 1: Fly ash based; Part 2: Calcined clay based)
Composition: OPC clinker + 15–35% pozzolana (fly ash or calcined clay)
Pozzolanic reaction: $SiO_2$ (reactive) + $Ca(OH)_2$ → C–S–H (secondary)
Blaine fineness: ≥ 300 $m^2$/kg
Strength: 28-day ≥ 33 MPa; slower early strength than OPC
Advantages: Lower heat of hydration, better workability, improved long-term durability, reduced permeability, resistance to sulphate and chloride attack, utilises industrial waste
Uses: General construction, mass concrete, marine works, underground structures

Portland Blast Furnace Slag Cement (PBFSC)

IS Code: IS 455:1989
Composition: OPC clinker + granulated blast furnace slag (GBFS) 25–65%; GGBS (Ground Granulated)
Slag is latently hydraulic; activated by $Ca(OH)_2$ released during OPC hydration
Blaine fineness: ≥ 225 $m^2$/kg
Advantages: Low heat, sulphate resistance, lower permeability, better workability, long-term strength
Uses: Marine structures, foundations, mass concrete, road base

Masonry Cement

IS Code: IS 3466:1988
Composition: OPC + inert or pozzolanic filler (≥ 40%)
IST ≥ 90 min; FST ≤ 1440 min (24 hrs)
Lower strength; improved workability and plasticity for mortar
Uses: Masonry mortar, plastering, jointwork — never structural concrete

White Portland Cement

IS Code: IS 8042:1989
Composition: Very low $Fe_2O_3$ (< 0.5%) and MnO → white colour; AM very high
Raw materials: white chalk/limestone + white kaolin clay; special fuel (oil/gas not coal)
More expensive; similar strength to OPC
Uses: Decorative finishes, floor tiles, architectural concrete, swimming pools

Coloured Cement

White cement + suitable pigments (3–10%)
Pigments: red ($Fe_2O_3$), green ($Cr_2O_3$), blue (cobalt oxide), yellow (iron hydroxide)
Pigments must be alkali-resistant and non-fading

Air-Entraining Portland Cement

IS Code: IS 8043:1991
Interground air-entraining agent (AEA) added during clinker grinding
Produces uniformly distributed micro air bubbles (25–250 µm) in concrete
Uses: Cold climate regions; freeze-thaw resistance; road concrete

Hydrophobic Portland Cement

IS Code: IS 8043:1991
Oleic acid / stearic acid coats cement grains → prevents moisture absorption during storage
Shelf life extended; used in tropical / humid storage conditions
The coating wears off during mixing — no long-term effect on concrete

Expansive Cement

No dedicated IS code; used in special applications
Types: Ettringite-based (Type K, M, S), Calcium oxide–based, Metallic powder–based
Expansion mechanism: controlled formation of Ettringite after setting → compensates shrinkage
Uses: Chemical-prestressed concrete, grouting bolt holes, shrinkage-compensating overlays

🏗

Ch 7 · Types of Cement — Key Numbers

RHPC 3-day strength

≈ OPC 33's 28-day strength

Achieved via higher C₃S (up to 70%) and finer grinding

—

SRPC $C_3A$ limit

≤ 5% (and $C_3A+C_4AF$ ≤ 25%)

Minimises Ettringite formation from sulphate attack

PPC pozzolana content

15 – 35% of clinker blend

Fly ash or calcined clay (IS 1489)

PBFSC slag content

25 – 65% GGBS

IS 455; latently hydraulic, activated by Ca(OH)₂

🏗

Ch 7 · Applied Scenarios

"Which cement?" reasoning — common ESE descriptive style

A raft foundation for a large dam requires a huge, thick pour of concrete. Which type of cement should be specified, and why?

Approach hint

Think about what happens in very thick concrete sections if the heat of hydration is high.

Thick pours trap heat — high-HOH cement causes large temperature differentials → thermal cracking
Low Heat Portland Cement (LHPC) has low $C_3S$/$C_3A$ and high $C_2S$ → HOH ≤ 272 kJ/kg at 7 days
PPC or PBFSC are also acceptable low-heat alternatives

✓ Low Heat Portland Cement (or PPC/PBFSC) — minimises thermal cracking risk in mass concrete

A sewage treatment plant needs concrete pipes and structures resistant to aggressive sulphate soils. Which cement is best suited?

Approach hint

Sulphate resistance is governed primarily by $C_3A$ content.

Sulphate attack targets $C_3A$ → forms expansive Ettringite
SRPC ($C_3A \leq 5\%$) is specifically engineered for this
Supersulphated Cement (SSC) is an even stronger alternative for very aggressive sulphate/acid exposure

✓ Sulphate Resisting Portland Cement (SRPC), or SSC for extreme exposure

🏗

Ch 7 · Diagrams

Click any diagram to zoom

Quick cement-selection decision guide by site condition

🏗

Ch 7 · Quick Quiz

3 questions · tap an option to reveal answer

Question 1

Masonry cement should never be used for:

Masonry cement has low strength and is meant only for mortar/plastering — never for structural RCC ✓

Question 2

White Portland Cement achieves its colour mainly by keeping which oxide very low?

Iron oxide content is kept below 0.5% (and MnO minimised) since $Fe_2O_3$ is what gives ordinary cement its grey colour ✓

Question 3

Air-Entraining Portland Cement is primarily used for resistance to:

The interground air-entraining agent creates micro air voids that relieve the pressure of freezing water in the pores, protecting against freeze–thaw damage ✓

🔥

Ch 8 · Special Cements

Composition, Properties & Uses

○ Not Started

High Alumina Cement (HAC / Aluminous Cement / Ciment Fondu)

Feature	Details
IS Code	IS 6452:1989
Raw materials	Bauxite ($Al_2O_3$ source) + limestone; fusion process at ~1500°C
Main compound	Monocalcium Aluminate (CA = CaO·$Al_2O_3$) — ~40%
$Al_2O_3$ content	> 32%
IST	≥ 30 min
FST	≤ 360 min (6 hrs)
24-hour strength	> 40 MPa — extremely rapid strength gain
28-day strength	≥ 45 MPa
Heat of hydration	~560 kJ/kg (very high)
Temperature resistance	Retains strength up to 1000°C (refractory grade)
Conversion	Metastable $CAH_{10}$ converts to stable $C_3AH_6$ (cubic) over time — significant strength loss (30–50%); promoted by heat and moisture

⚠ Conversion of HAC: $CAH_{10}$ (hexagonal) → $C_3AH_6$ (cubic) + $Al(OH)_3$ + $H_2O$. This conversion increases porosity and reduces strength by 30–50%. HAC must NOT be used in structural concrete where loads are sustained — it is reserved for refractory/high-temperature applications.

Uses: Refractory lining of furnaces, kilns, chimneys; chemical plant floors; emergency/repair work; cold-weather concreting
Good resistance to weak acids, seawater (calcium aluminate pastes are acid-resistant)
Not suitable for prolonged contact with alkalis

Supersulphated Cement (SSC)

IS Code: IS 6909:1990
Composition: 80–85% granulated GGBS + 10–15% calcium sulphate (anhydrite or gypsum) + small amount of OPC or lime as activator
Very low $C_3A$; hydration produces Ettringite as primary phase → dense microstructure
Strength: Slow early gain but good 28-day and long-term strength
Heat of hydration: Very low (~167–180 kJ/kg at 7 days)
Chemical resistance: Excellent against sulphates, acids, seawater
Uses: Sewers, foundations in sulphate soils, marine structures, chemical plants
Must be used with higher water content; sensitive to temperature (do not use in hot weather)

Oil Well Cement

IS Code: IS 8229:1986 (based on API standards)
Designed to be pumped and set at high temperatures (up to 150°C) and high pressures (> 100 MPa)
API grades A–J; Grade G and H most common internationally
Low $C_3A$ (< 3%) and coarser grind → slower setting at surface; retarder admixtures added
Uses: Cementing steel casings in oil/gas wells to seal formation fluids

Tricalcium Silicate Cement (Mineral Trioxide Aggregate – MTA)

Used in dentistry / endodontics — not a construction material but occasionally mentioned in ESE
Biocompatible; sets in moist conditions

Pozzolana Cement (Natural Pozzolana)

IS Code: IS 1344:1981 (calcined pozzolana)
Natural pozzolanas: volcanic ash (trass), diatomite, rice husk ash, silica fume, fly ash
Definition: Pozzolana is a siliceous and/or aluminous material that has little or no cementitious value alone but reacts chemically with $Ca(OH)_2$ in the presence of water to form compounds with cementitious properties

Comparison of Special Cements

Cement	HOH	Early Strength	Sulphate Resistance	Key Use
RHPC	High	Very High	Low	Emergency repairs
Low Heat	Very Low	Low	Moderate	Mass concrete
SRC	Moderate	Moderate	Very High	Marine / sulphate soil
HAC	Very High	Extremely High	High (acids)	Refractory concrete
SSC	Very Low	Low	Excellent	Sewers, chemical plants
PPC	Low	Low–Moderate	Good	General / mass concrete
PBFSC	Low	Moderate	Good	Marine / mass concrete

🔥

Ch 8 · Special Cements — Key Numbers

HAC 24-hour strength

> 40 MPa

Extremely rapid strength gain (fusion process, ~1500°C)

MPa

HAC conversion strength loss

30 – 50%

$CAH_{10} \rightarrow C_3AH_6$; promoted by heat & moisture

SSC composition

80–85% GGBS + 10–15% $CaSO_4$

+ small OPC/lime activator

Oil well cement service conditions

Up to 150°C, > 100 MPa

API grades A–J; low $C_3A$ < 3%

°C / MPa

🔥

Ch 8 · Solved Examples

GATE CE / ESE level

An HAC concrete element develops 55 MPa strength shortly after casting. Due to sustained warm, humid service conditions, full conversion occurs, causing a 40% strength loss. Estimate the residual strength, and comment on suitability for a load-bearing structural member.

Approach hint

Apply the 40% loss directly to the initial strength, then compare against what a structural member would need long-term.

Strength loss = $0.40 \times 55 = 22$ MPa
Residual strength = $55 - 22 = 33$ MPa
Even though 33 MPa sounds adequate, conversion is progressive and unpredictable under sustained heat/moisture — this is exactly why codes prohibit HAC in permanent load-bearing structural concrete

✓ Residual strength ≈ 33 MPa, but HAC is unsuitable for sustained structural loading regardless of the numeric result — reserve it for refractory or non-structural/repair applications

🔥

Ch 8 · Diagrams

Click any diagram to zoom

HAC conversion: the metastable hexagonal hydrate converts to the denser cubic form over time, losing 30–50% of its strength as porosity increases

🔥

Ch 8 · Quick Quiz

3 questions · tap an option to reveal answer

Question 1

High Alumina Cement should NOT be used in:

HAC conversion causes unpredictable, progressive strength loss (30–50%) — unsafe for permanent load-bearing structures ✓

Question 2

Supersulphated Cement (SSC) is composed mainly of:

SSC is 80–85% GGBS + 10–15% calcium sulphate with a small OPC/lime activator ✓

Question 3

Oil well cement is engineered mainly to withstand:

Oil well cement must be pumped down a well and set reliably at up to 150°C and >100 MPa — low $C_3A$ and retarders keep it workable long enough to place ✓

🧴

Ch 9 · Admixtures for Cement & Concrete

○ Not Started

Definition & Classification

Admixtures are materials other than cement, water and aggregates that are added to a concrete mixture immediately before or during mixing to modify its properties in the fresh or hardened state.

Category	Type	Mechanism
Chemical admixtures	Plasticizers (Water Reducers)	Disperse cement particles → improve workability at same w/c
	Superplasticizers (HRWR)	Steric / electrostatic repulsion; reduce water > 20%
	Retarders	Delay $C_3A$ / $C_3S$ hydration
	Accelerators	Speed up $C_3S$ hydration
	Air Entraining Agents (AEA)	Surfactants; stabilise micro air bubbles
Mineral admixtures	Fly Ash (Class F & C)	Pozzolanic; Class C also cementitious
	GGBS (Slag)	Latent hydraulic; activated by $Ca(OH)_2$
	Silica Fume (Microsilica)	Highly reactive pozzolan; ultra-fine (0.1 µm)
	Metakaolin	Calcined kaolin; reactive pozzolan

Chemical Admixtures — Detailed

Plasticizers (Normal Water Reducers)

Feature	Details
IS Code	IS 9103:1999
Water reduction	5–10%
Chemical types	Lignosulfonates (LS), Hydroxylated carboxylic acids, Gluconates
Effect	Same workability at lower w/c; or increased slump at same w/c
Retarding effect	Mild; adds ~30–60 min to setting time

Superplasticizers (High Range Water Reducers – HRWR)

Feature	Details
IS Code	IS 9103:1999
Water reduction	15–30%
Dosage	0.2–3% by mass of cement
Types	1st gen: SNF (Sulfonated Naphthalene Formaldehyde), SMF (Sulfonated Melamine Formaldehyde); 2nd gen: Modified lignosulfonates; 3rd gen (latest): PCE (Polycarboxylate Ether) — most effective; comb-polymer structure
Slump life	SNF/SMF: 30–60 min; PCE: 60–90 min or more
Applications	SCC, HPC, ready-mix concrete, pumped concrete

Retarders

Delay initial and final setting time by 1–4 hours
Types: Sugar / sucrose (most effective retarder; 0.1% reduces strength; 0.3% = total retardation), lignosulfonates, hydroxycarboxylic acids, phosphates
Uses: Hot weather concreting (T > 35°C), long transport in transit mixers, large pours, complex formwork
Caution: Excess sugar acts as a set retarder → completely inhibits setting

Accelerators

Speed up hydration → faster set and early strength
Calcium Chloride ($CaCl_2$): Most effective; 1–2% by mass; reduces IST by 30–50%; BUT causes corrosion of steel → NOT permitted in RCC or prestressed concrete
Non-chloride accelerators: Calcium formate, calcium nitrite, triethanolamine; safer for RCC
Uses: Cold weather concreting (T < 5°C), precast, emergency works

Air Entraining Agents (AEA)

Create uniformly distributed, stable spherical micro air voids (25–250 µm diameter)
Air content: 3–7% by volume
Types: Vinsol resin, fatty acid salts (sodium oleate), neutralised wood resins, synthetic surfactants
Benefits: Freeze-thaw resistance, improved workability, reduced bleeding and segregation
Effect on strength: Each 1% increase in air reduces compressive strength by ~5%
Uses: Concrete in cold climates; roads in freeze-thaw zones; pavements

Mineral Admixtures — Detailed

Fly Ash (FA)

Feature	Class F (Low Calcium)	Class C (High Calcium)
Source	Sub-bituminous / bituminous coal	Lignite coal; high CaO (15–40%)
$SiO_2 + Al_2O_3 + Fe_2O_3$	≥ 70%	≥ 50%
Activity	Pozzolanic only	Pozzolanic + cementitious
Replacement level in concrete	15–35%	Up to 50%
IS Code	IS 3812:2013

Particle size: 1–100 µm; spherical glassy particles (improve workability — ball bearing effect)
Pozzolanic reaction: $SiO_2 + Ca(OH)_2 + H_2O \rightarrow$ C–S–H (secondary)
Benefits: Reduced HOH, improved long-term strength, better durability, reduced permeability, ASR mitigation

Ground Granulated Blast Furnace Slag (GGBS)

IS Code: IS 12089:2013
By-product of iron manufacture; rapidly quenched → glassy, latent hydraulic material
Chemical composition: CaO 30–45%; $SiO_2$ 30–37%; $Al_2O_3$ 8–20%; MgO 1–12%
Hydraulic activity index: ≥ 70% at 7 days; ≥ 90% at 28 days (compared to OPC control)
Replacement level: 30–70% (up to 80% in some applications)
Benefits: Very low HOH, excellent sulphate and chloride resistance, low permeability, high long-term strength

Silica Fume (SF / Microsilica)

IS Code: IS 15388:2003
By-product of silicon / ferrosilicon alloy production (electric arc furnace)
Ultra-fine (average 0.1–0.15 µm; 100× finer than cement); amorphous $SiO_2 >$ 85%
Very high pozzolanic activity (much faster than fly ash)
Pore refinement: fills spaces between cement particles → dramatically reduces capillary porosity
Addition: 5–10% replacement; always use with superplasticizer
Benefits: Very high strength (70–150+ MPa possible), extremely low permeability, excellent durability
Used in HPC, bridge decks, offshore structures, parking structures

🧴

Ch 9 · Admixtures — Key Numbers

Plasticizer water reduction

5 – 10%

IS 9103; lignosulfonates, hydroxylated carboxylic acids

Superplasticizer water reduction

15 – 30%

Dosage 0.2–3%; PCE is the most effective type

$CaCl_2$ accelerator dosage

1 – 2% by mass

Reduces IST 30–50%; BANNED in RCC/prestressed concrete (corrosion risk)

Air-entrainment strength penalty

≈ 5% strength loss per 1% air

Trade-off for freeze-thaw resistance

🧴

Ch 9 · Solved Examples

GATE CE / ESE level

A concrete mix needs 200 kg/m³ of water without any admixture. If a PCE superplasticizer achieving 25% water reduction is used while keeping the same workability, find the new water content and the resulting w/c if cement content stays at 400 kg/m³.

Approach hint

Reduce the water content by 25%, then recompute w/c with the unchanged cement content.

Water reduction = $0.25 \times 200 = 50$ kg
New water content = $200 - 50 = 150$ kg/m³
New $w/c = 150/400 = 0.375$ (down from $200/400 = 0.50$)

✓ New water content = 150 kg/m³, w/c reduced from 0.50 to 0.375 — this is exactly how superplasticizers enable high-strength concrete without losing workability

An air-entrained concrete has 5% entrained air, compared to a control mix with negligible air. Estimate the expected compressive strength loss due to the entrained air alone.

Approach hint

Apply the rule-of-thumb ~5% strength loss per 1% air content.

Strength loss ≈ $5\% \times 5 = 25\%$

✓ ≈ 25% strength loss — this trade-off is accepted where freeze-thaw durability is the governing design criterion (e.g., pavements in cold climates)

🧴

Ch 9 · Diagrams

Click any diagram to zoom

Plasticizers create electrostatic/steric repulsion between cement grains, breaking up flocs and freeing trapped water — the same paste becomes more workable at a lower water content

🧴

Ch 9 · Quick Quiz

3 questions · tap an option to reveal answer

Question 1

Which accelerator is NOT permitted in reinforced or prestressed concrete?

Calcium chloride is the most effective accelerator but promotes corrosion of embedded steel — banned in RCC and prestressed concrete ✓

Question 2

Which mineral admixture is roughly 100× finer than ordinary cement particles?

Silica fume (0.1–0.15 µm average) is roughly 100 times finer than cement, giving it extremely high, fast pozzolanic activity ✓

Question 3

Class C fly ash differs from Class F mainly in that it:

Class C fly ash (from lignite coal) has high CaO (15–40%) giving it self-cementing properties in addition to pozzolanic activity, unlike Class F ✓

📚

Ch 10 · Revision & Practice

IS codes, quick-recall tables, mnemonics, PYQ pattern, mini quiz and practice questions

○ Not Started

Complete IS Code Reference for Cement

IS Code	Year	Subject
IS 269	2015	Ordinary Portland Cement (OPC 33 grade) specification
IS 8112	2013	Ordinary Portland Cement (OPC 43 grade) specification
IS 12269	2013	Ordinary Portland Cement (OPC 53 grade) specification
IS 8041	1990	Rapid Hardening Portland Cement
IS 12600	1989	Low Heat Portland Cement
IS 12330	1988	Sulphate Resisting Portland Cement
IS 1489 Pt1	1991	Portland Pozzolana Cement – Fly Ash based
IS 1489 Pt2	1991	Portland Pozzolana Cement – Calcined Clay based
IS 455	1989	Portland Blast Furnace Slag Cement
IS 6452	1989	High Alumina Cement
IS 6909	1990	Supersulphated Cement
IS 8042	1989	White Portland Cement
IS 8043	1991	Hydrophobic Portland Cement / Air Entraining Portland Cement
IS 3466	1988	Masonry Cement
IS 8229	1986	Oil Well Cement
IS 1344	1981	Calcined Natural Pozzolana Cement
IS 4031	Various	Methods of physical tests for hydraulic cement (Parts 1–15)
IS 4032	1985	Methods of chemical analysis of hydraulic cement
IS 3812	2013	Pulverised Fuel Ash (Fly Ash) specification
IS 12089	2013	Granulated Slag for Portland Slag Cement
IS 15388	2003	Silica Fume specification
IS 9103	1999	Admixtures for Concrete

All-in-One Cement Properties Quick Table

Cement Type	HOH	Early Str.	Sulphate R.	Blaine (m²/kg)	IST (min)
OPC 33/43/53	Medium	Medium–High	Low	≥ 225	≥ 30
RHPC	High	Very High	Low	≥ 325	≥ 30
Low Heat	Very Low	Low	Medium	≥ 320	≥ 60
SRC	Medium–Low	Medium	Very High	≥ 225	≥ 30
PPC	Low	Low–Med	Good	≥ 300	≥ 30
PBFSC	Low	Medium	Good	≥ 225	≥ 30
HAC	Very High	Extremely High	Good (acids)	≥ 225	≥ 30
SSC	Very Low	Low	Excellent	–	≥ 30
White	Medium	Medium	Low	≥ 300	≥ 30
Masonry	Low	Low	Low	–	≥ 90

Critical Numerical Values to Memorise

Parameter	Value
Specific gravity of OPC	3.10 – 3.15
Bulk density of cement (loose)	~1440 kg/m³
Normal consistency (P)	26 – 33%
Water for setting time test	0.85 P
Water for Le Chatelier test	0.78 P
IST (OPC, RHPC, SRC, PPC, PBFSC, HAC)	≥ 30 min
IST (Low Heat)	≥ 60 min
IST (Masonry Cement)	≥ 90 min
FST (most cements)	≤ 600 min (10 hrs)
FST (HAC)	≤ 360 min (6 hrs)
FST (Masonry)	≤ 1440 min (24 hrs)
Soundness – Le Chatelier limit	≤ 10 mm (OPC)
Soundness – Autoclave expansion	≤ 0.80%
Fineness (sieve) limit	≤ 10% on 90 µm sieve
Blaine fineness (OPC)	≥ 225 m²/kg
Blaine fineness (RHPC)	≥ 325 m²/kg
Blaine fineness (PPC)	≥ 300 m²/kg
Clinker burning zone temperature	1350 – 1450°C
Calcination temperature	~900°C
$C_3A$ limit in SRC	≤ 5%
$C_3A + C_4AF$ limit in SRC	≤ 25%
$C_3S$ in Low Heat Cement	≤ 35%
$C_2S$ in Low Heat Cement	≥ 40%
$C_3A$ in Low Heat Cement	≤ 6%
HOH at 7 days (Low Heat)	≤ 272 kJ/kg
HOH at 28 days (Low Heat)	≤ 314 kJ/kg
MgO limit in OPC	≤ 6%
$SO_3$ limit in OPC	≤ 3.0% ($C_3A \leq$ 5%); ≤ 3.5% ($C_3A >$ 5%)
LOI limit in OPC	≤ 5.0%
LSF range (IS 269)	0.80 – 1.02
Shelf life of cement	3 months from manufacture
Min. w/c for complete hydration (theory)	0.23
Min. w/c for complete hydration (practical)	0.36
$C_3S$ HOH	~502 J/g
$C_2S$ HOH	~260 J/g
$C_3A$ HOH	~867 J/g
$C_4AF$ HOH	~419 J/g
$Al_2O_3/Fe_2O_3$ min ratio (OPC)	≥ 0.66
Air entraining agent water reduction	None; air content 3–7%
Superplasticizer water reduction	15–30%
Plasticizer water reduction	5–10%
HAC: 24-hr compressive strength	> 40 MPa

Bogue Formulae (exam-ready)

$C_3S$

$$ 4.071C - 7.600S - 6.718A - 1.430F - 2.852\bar{S} $$

C=CaO, S=$SiO_2$, A=$Al_2O_3$, F=$Fe_2O_3$, S̄=$SO_3$

$C_2S$

$$ 2.867S - 0.7544\,C_3S $$

Needs $C_3S$ computed first

$C_3A$

$$ 2.650A - 1.692F $$

Independent calculation

$C_4AF$

$$ 3.043F $$

Simplest — direct proportion

LSF / SM / AM

$$ \tfrac{C}{2.8S+1.2A+0.65F},\ \tfrac{S}{A+F},\ \tfrac{A}{F} $$

Targets: 0.80–1.02, 1.7–4.0, 1–4

—

Alkali equivalent

$$ Na_2O + 0.658\,K_2O \leq 0.60\% $$

Low-alkali cement threshold

Mnemonics

💡 Bogue compounds by decreasing % in OPC: "Some Silly Cats Are Fighting" — $C_3$S (~50%) → $C_2$S (~25%) → $C_4$AF (~12%) → $C_3$A (~10%)

Heat of hydration (decreasing): "Three-Aluminate is the Hottest; Two-Silicate is the Coolest" — $C_3A > C_3S > C_4AF > C_2S$

Which cement for which problem:
Hot weather / mass concrete → Low Heat or PPC
Sulphate soil / marine → SRC or PBFSC
Emergency repair → RHPC or HAC
High-strength concrete → OPC 53 + Silica Fume
Decorative work → White Cement
Grouting wells → Oil Well Cement
Chemical plant sewers → SSC or SRC

GATE / ESE Previous Year Pattern

Topic	Frequency	Question Type
Bogue compound calculation (from oxide %)	Every alternate year (GATE)	NAT / MCQ
Setting time and soundness test values	Very high	MCQ
Which cement to use for a given situation	Very high (ESE)	MCQ
Heat of hydration order / values	High	MCQ
LSF / Moduli calculation	Moderate (GATE)	NAT
Flash set vs false set	Moderate	MCQ
IS codes for cement types	High (ESE / SSC JE)	MCQ
Hydration products (C–S–H, ettringite)	Moderate	MCQ
HAC conversion reaction and consequences	Moderate (ESE)	MCQ / Descriptive
Admixture types and effects	Moderate	MCQ
Pozzolana definition and reaction	Moderate	MCQ

Mini Quiz

The Bogue formula $C_2S = 2.867\,SiO_2 - 0.7544\,C_3S$ requires which value to be computed first?

$C_3S$ must be calculated first since $C_2S$ subtracts $0.7544 \times C_3S$ ✓

The IS 269 acceptable LSF range is:

IS 269 restricts LSF to 0.80–1.02 (narrower than the theoretical 0.66–1.02 workable range) ✓

Which test detects unsoundness due to free magnesia (periclase)?

The Autoclave test (2 MPa, 3 hrs) specifically targets free-MgO expansion; Le Chatelier targets free CaO ✓

Which cement type has the lowest heat of hydration among those listed in the quick table?

Low Heat Portland Cement and Supersulphated Cement both target "Very Low" HOH — ideal for mass concrete ✓

Calcium chloride accelerator is prohibited in RCC primarily because it:

Chloride ions promote corrosion of steel reinforcement, so $CaCl_2$ is banned in RCC and prestressed concrete despite being a very effective accelerator ✓

Practice Questions

EasyState the two moduli, besides LSF, used in raw-mix design, and their typical ranges.

Silica Modulus (SM), typical 1.7–4.0, and Alumina Modulus (AM), typical 1–4 (>10 for white cement).

EasyWhy is gypsum added during cement grinding?

To control the reactivity of C₃A by forming Ettringite, preventing flash set. Added at 3–5%; more than 3.5% SO₃ risks false set/expansion.

MediumOxide analysis gives CaO=63%, SiO₂=20%, Al₂O₃=6%, Fe₂O₃=3%, SO₃=2%. Compute C₃S and C₄AF.

C₃S = 4.071(63) − 7.600(20) − 6.718(6) − 1.430(3) − 2.852(2) = 256.5 − 152.0 − 40.3 − 4.29 − 5.70 ≈ 54.2%. C₄AF = 3.043(3) ≈ 9.1%.

MediumA site engineer wants to reduce water content by 20% without losing workability, using the cheapest admixture that achieves this. Which category of admixture is appropriate, and why not a simple plasticizer?

A superplasticizer (HRWR) is needed — ordinary plasticizers only achieve 5–10% water reduction, while superplasticizers achieve 15–30%, comfortably covering the 20% target.

HardExplain, with reference to compound chemistry, why Low Heat Portland Cement gains strength more slowly than OPC but eventually matches or exceeds it.

LHPC has low C₃S (≤35%) and low C₃A (≤6%) but high C₂S (≥40%). C₃S drives early strength but C₂S drives long-term strength and keeps reacting for years (up to ~160% of 28-day strength at 1 year), so the compound shift trades early strength for lower heat and comparable/better ultimate strength.

Compound	Hydration Reaction	Products
\(C_3S\) (Alite)	\(2C_3S + 6H \rightarrow C_3S_2H_3 + 3Ca(OH)_2\)	C–S–H gel + Portlandite
\(C_2S\) (Belite)	\(2C_2S + 4H \rightarrow C_3S_2H_3 + Ca(OH)_2\)	C–S–H gel + less Portlandite
\(C_3A\) (initial, with gypsum)	\(C_3A + 3C\bar SH_2 + 26H \rightarrow C_6AS_3H_{32}\)	Ettringite (AFt phase) — prevents flash set
\(C_3A\) (after gypsum exhausted)	\(2C_3A + C_6AS_3H_{32} + 4H \rightarrow 3C_4A\bar SH_{12}\)	Monosulphate (AFm phase)
\(C_4AF\)	\(C_4AF + 2Ca(OH)_2 + 10H \rightarrow C_6AFH_{12}\)	Calcium aluminoferrite hydrate

Group	Chemical Nature	Sources	Provides
Calcareous materials	\(CaCO_{3}\)-rich	Limestone, chalk, marl, calcareous shale, sea shells	CaO (lime) — 60–67% of cement
Argillaceous materials	\(SiO_{2}\), \(Al_{2}O_{3}\), \(Fe_{2}O_{3}\)-rich	Clay, shale, laterite, blast furnace slag	Silica, alumina, iron oxide

Compound	Abbreviation	Full Chemical Name	Formula	% in OPC
Alite	\(C_3S\)	Tricalcium Silicate	3CaO·\(SiO_2\)	40–50%
Belite	\(C_2S\)	Dicalcium Silicate	2CaO·\(SiO_2\)	25–35%
Celite (aluminate phase)	\(C_3A\)	Tricalcium Aluminate	3CaO·\(Al_2O_3\)	5–12%
Ferrite phase	\(C_4AF\)	Tetracalcium Aluminoferrite	4CaO·\(Al_2O_3\)·\(Fe_2O_3\)	8–14%

Oxide	Full formula	Notation
Calcium oxide (lime)	CaO	C
Silicon dioxide (silica)	\(SiO_2\)	S
Aluminium oxide (alumina)	\(Al_2O_3\)	A
Iron oxide	\(Fe_2O_3\)	F
Water	\(H_2O\)	H
Sulphur trioxide	\(SO_3\)	S̄

Stage	Time	What Happens
Pre-induction / Initial	0–15 min	Rapid dissolution of \(C_3A\); first ettringite forms; early heat release spike
Induction / Dormant	15 min–3 hrs	Slow reaction; cement remains workable; ion concentration builds
Acceleration	3–8 hrs	\(C_3S\) hydration accelerates; C–S–H nucleates rapidly; initial set
Deceleration	8–24 hrs	Reaction slows as products form a diffusion barrier around grains; final set
Slow / Long-term	24 hrs onwards	Continued hydration; gradual pore refinement; strength development for months/years

Feature	Flash Set	False Set
Cause	Rapid reaction of \(C_3A\) with insufficient gypsum	Dehydration of gypsum (\(CaSO_4 \cdot 2H_2O \rightarrow CaSO_4 \cdot \tfrac{1}{2}H_2O\)) during hot grinding
Heat release	Significant heat	No significant heat
Remixing	Cannot be restored by remixing	Can be restored by vigorous remixing (re-dissolves \(CaSO_4 \cdot \tfrac{1}{2}H_2O\))
Product	Ettringite (expansive)	Re-hydrated gypsum (no expansion)

Chemical Property	Requirement (OPC)	Significance
Ratio (\(Al_2O_3 / Fe_2O_3\))	≥ 0.66	Ensures \(C_3A\) forms; important for setting & strength
Lime Saturation Factor (LSF)	0.80 – 1.02	Ensures no excess free CaO; proper clinker composition
Insoluble residue	≤ 2.0%	Indicates purity; siliceous adulterants detected
Magnesia (MgO)	≤ 6.0%	Excess MgO (periclase) causes delayed expansion
Sulphur trioxide (\(SO_3\))	≤ 3.0% (\(C_3A\) ≤ 5%); ≤ 3.5% (\(C_3A >\) 5%)	Excess \(SO_3\) causes expansion and cracking
Loss on Ignition (LOI)	≤ 5.0%	Indicates pre-hydration, adulteration or excess gypsum
Chloride (\(Cl^-\))	≤ 0.05%	Excess chloride causes corrosion of steel reinforcement
Total alkalis (\(Na_2O\) equivalent)	≤ 0.60% (low alkali cement)	High alkalis trigger alkali–silica reaction (ASR) with reactive aggregates

Learning Objectives

Exam Relevance

Concept Map

Where This Fits

Two Principal Groups

Approximate Oxide Composition of OPC

The Three Raw-Mix Moduli

Two Main Processes

Steps in Dry Process (Modern)

Reactions in the Rotary Kiln (Temperature Zones)

Clinker Composition

Bogue's Compounds — Complete Table

Properties of Each Compound — Comparison

Strength Development (% of 28-day strength)

Heat of Hydration (HOH) Order

Cement Notation (Abbreviated Oxide Notation)

Definition & Mechanism

Hydration Reactions (Complete)

Stages of Hydration (Le Chatelier Stages)

Setting vs Hardening

Flash Set vs False Set

Degree of Hydration (α) and Water Requirements

Products of Hydration and Their Volume

Summary of IS 4031 Tests

1. Fineness Test (IS 4031 Part 1 — Sieving)

2. Fineness Test — Blaine's Air Permeability (IS 4031 Part 2)

3. Standard Consistency Test (IS 4031 Part 4)

4. Setting Time Test (IS 4031 Part 5)

5. Soundness Test (IS 4031 Part 3)

6. Compressive Strength Test (IS 4031 Part 6)

Physical Requirements Summary (OPC IS 269:2015)

Chemical Requirements as per IS 269:2015

Sulphate Attack Mechanism

Chloride Content in Concrete (IS 456:2000)

Ordinary Portland Cement (OPC)

Other Portland Cement Variants

Rapid Hardening Portland Cement (RHPC)

Low Heat Portland Cement (LHPC)

Sulphate Resisting Portland Cement (SRPC)

Portland Pozzolana Cement (PPC)

Portland Blast Furnace Slag Cement (PBFSC)

Masonry Cement

White Portland Cement

Coloured Cement

Air-Entraining Portland Cement

Hydrophobic Portland Cement

Expansive Cement

High Alumina Cement (HAC / Aluminous Cement / Ciment Fondu)

Supersulphated Cement (SSC)

Oil Well Cement

Tricalcium Silicate Cement (Mineral Trioxide Aggregate – MTA)

Pozzolana Cement (Natural Pozzolana)

Comparison of Special Cements

Definition & Classification

Chemical Admixtures — Detailed

Plasticizers (Normal Water Reducers)

Superplasticizers (High Range Water Reducers – HRWR)

Retarders

Accelerators

Air Entraining Agents (AEA)

Mineral Admixtures — Detailed

Fly Ash (FA)

Ground Granulated Blast Furnace Slag (GGBS)

Silica Fume (SF / Microsilica)

Complete IS Code Reference for Cement

All-in-One Cement Properties Quick Table

Critical Numerical Values to Memorise

Bogue Formulae (exam-ready)

Mnemonics

GATE / ESE Previous Year Pattern

Mini Quiz

Practice Questions

Related Topics & Continue Learning