Recent growth of construction industry has increased the demand of cement. Increase of the cement utilization demands for higher production efficiency and ultimately low production cost. The efficiency of the cement production depends greatly upon the efficiency of a grinding mill which consumes 60-70% of the total electricity consumption of the cement plant[12]. A grinding mill (Ball Mill) is used to grind the cement clinker into fine cement powder. Grinding Aids are used to improve the grinding efficiency and reduce power consumption. This paper discusses the grinding aids mechanism and improvement in grinding efficiency due to various grinding aids viz .polyols, amines . This paper also focus on the effects of grinding aids on the mechanical properties of cement such as setting time, specific surface, compressive strength at various stages.

1. Grinding Aids For Cement
Prepared by:
Shyam R. Anandjiwala
(Construction Management)
INDIAN INSTITUTE OF TECHNOLOGY DELHI

2. What are Grinding Aids?
• Grinding mill grinds the hard clinker into fine
cement powder.
• Additives used to improve the grinding
efficiency of grinding mill.
• Improvement in grinding efficiency leads to
reduction in electricity consumption.
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3. History of Grinding Aids
• The history of cement additives goes back to the
1930s.
• Attempt was made to disperse carbon black in
concrete with the help of triethanolamine to
solve mottling issue and to improve the strength
of concrete. This chemical is given name
“Tucker’s Dispersion Aid”.
• By 1960, TDA from Dewey and Almy, 109-B from
Master Builders and Polyfon T from West Virginia
Pulp and Paper (now Westvaco) were the only
approved grinding aids under ASTM.
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4. Why Grinding Aids should be used?
• Grinding of clinker is affected by cleavage,
microcracks or the defects present in its
crystal structure.
• Applied shear stress on clinker breaks the
ionic bonds and highly reactive positive &
negative charges are produced.
• High surface energy on clinker surface
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5. • Formation of electrostatic charges on surface
cause agglomeration of cement particles.
• Decrease in surface area and increase in
electricity consumption.
• High surface energy causing “Pack set”
• Grinding aids neutralize the electrostatic
charges and inhibits the pack set of cement.
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Why Grinding Aids should be used?(contd.)

6. • Allows the cement transport in delivery trucks
and storage in silos without lump formation.
• Better material handling due to improved fluidity.
• Elimination of ‘’coating’’ effect of the clinker on
grinding media and grinding mill walls.
• To either increase the surface area of cement at
the given production rate or it can increase the
production rate of cement keeping the surface
area constant.
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Why Grinding Aids should be used?(contd.)

7. Fig1. The milling media(balls)
coated themselves with cement if
no grinding aid is used
Fig2. Grinding aids keep the
milling media (balls) clean and
increase the productivity
Sika Tech
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8. Commonly Used Grinding Aids
Amine based GAs
 Monoethanolamine(MEA)
 Diethanolamine(DEA)
 Triethanolamine(TEA)
 Triisopropanolamine(TIPA)
Alchohol based GAs
 Ethylene glycol(EG)
 Diethylene glycol(DEG)
Ether based GAs
 Poly Carboxylate Ether(PCE)
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9. Grinding Aid Mechanisms
1. Dispersion Mechanism
• 2 basic mechanisms through which dispersion
can take place between the organic molecules
1. Gas Transfer
2. Surface Contact Transfer
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10. Gas Transfer
• The temperature in grinding mill is generally in
the range of 80-120 °C.
• Alcohols with boiling points below grinding
temperature (eg.ethanol-see table 1) get
adsorbed weakly due to their high volatility.
• They can be smelt even on cold cement.
Therefore it can be assumed that they are
dispersed via gas transfer.
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11. Chemical Boiling Point(°C)
Ethanol 78
Propylene glycol(PG) 188
Diethylene glycol(DEG) 245
Triethanolamine(TEA) 335
Table 1 :Different Grinding Aids with their Boiling
Temperatures(°C)
Sika Tech
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12. Surface Contact Transfer
• Polymers such as PCEs are assumed to be
dispersed via surface contact transfer.
• During grinding they retain their action as a
plasticizer.
• Therefore evaporation mechanism is assumed
to be excluded.
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13. 2. Surface Energy Reduction
• Mixture with water
• Grinding aids reduce surface energy of clinker in 3 parts:
(1)clinker tries to lower its surface energy(E1)
(2) surface energy of the grinding aids(E2) increase due to the
gain through the surface energy of clinker
(3) clinker-grinding aid interfacial energy(E3) value should be
negative or very small positive.
• The surface energy of the clinker covered with grinding aid(E)
is the algebraic summation of E1,E2 and E3.
E= E3 + E2 + E3
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14. • If E = -ve that means the energy is released
and the grinding aid spreads out on clinker’s
surface.
• That means Grinding aids not only have to
reduce the surface energy of clinker(E1) but
also to get strongly adsorbed on the surface of
clinker particles and reduce interfacial
energy(E3).
• Nonpolar liquids can not be used as the
grinding aids even though they have low
surface energy.
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15. Effect of GA on Cement Composition
• Effect on C3S, C2S, C3A & C3A+gypsum
• C3A hydrates to hydrogarnet(C3AH6) before it
transforms to ettringite in absence of TEA.
• TEA accelerate the hydration of C3A .
• TEA accelerates the formation of ettringite
and as it increase, conversion from ettringite
to monosulphate is at faster rate.
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16. • Extends the induction period of C3S may be
due to formation of surface complex on the
hydrating C3S .
• TEA also increase the induction period of C2S
like C3S but the difference is the slow rate of
reaction with C2S.
• Peak due to the C3S formation is extended
with the addition of TEA which indicates the
hydration of C3S is retarded by TEA.
• So TEA accelerates the aluminate phase
hydration and retards the hydration of silicate
phase.
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17. Fig.3 Conduction calorimetric
curves of cement hydrated in the
presence of TEA
Fig.4 Conduction calorimetric
curves of cement hydrated in
the presence of CaCl2
T I M E. H O U R S
V.S.Ramachandran11-05-2015 Indian Institute of Technology,Delhi 17

18. Effect of GA on Mechanical Properties
GA affects the following mechanical
properties of cement:
setting time
surface area
 compressive strength
 mortar workability
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19. Setting Time
• It is not found out whether TEA is a retarder or
an accelerator .
• TEA acts as retarder at low dosage (up to 0.5 %)
but accelerates the hydration at higher dosage .
• High dosage TEA can be used as an accelerator in
place of CaCl2 to eliminate chloride attack.
• MEA and low dosage DEA does not cause much
alteration in setting time.
• TIPA increases both initial and final setting time
of cement due to its diffusion into pores and
cracks of clinker particles.
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20. Surface Area
• All the grinding aids increase the surface area
of cement .
Table 2.values of Blaine for different specific energy
consumption
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20J.Assad

21. 0
5
10
15
20
25
30
35
40
45
50
0 10 20 30 40 50 60 70
%increasetoreferencemix
specific energy consumption(kWh/ton)
0.08%
amine GA
0.08%
glycol GA
Fig 5. Comparison of % increase in surface area
(cm2/g) due to amine & glycol grinding aids
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22. • Grinding energy of the mill affects the
performance of grinding aids.
• At higher grinding energy the effectiveness of
grinding aids to increase surface area of
cement increase.
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23. Compressive Strength
• TIPA increase 7 days and 28 days compressive strength
of cement.
• Optimum dosage is 0.01-0.02% for the enhancement of
strength by TIPA.
• If dosage>optimum dosage it can increase the strength
further very little but it is not economical.
• Higher dosage of TIPA can cause air entrainment in
cement. This air entrainment can be as high as 2%
compared to the cement without any additives.
• Therefore TIPA is used with air detraining agent at
higher dosage.
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24. • Effectiveness of enhancement of strength by
TIPA also depends upon the tetra calcium
aluminoferrite (C4AF) content in clinker.
• C4AF content must be > 4% for the
improvement in strength using TIPA.
• At higher C4AF content effectiveness of TIPA
increases in increasing strength.
• The increase in 1 day strength of cement due
to addition of TEA as grinding aid is debatable.
• TEA decreases later age strength of cement.
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25. Explanations for the decrease in later age strength
due to TEA:
• Rapid early hydration may create a dense zone of
hydration product around the grains and retard
subsequent hydration.
• Formation of hydration product with higher density
may promote a more porous structure.
• Cement that has set in a few minutes has obviously not
been thoroughly mixed, and consequently there will be
a non-uniform distribution of hydration products
within the structure that will prevent the development
of full strength.
• Rapid formation of ettringite may alter the initial
matrix and disturb subsequent bonding characteristics.
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26. • Combinations of grinding aids can be used to
improve grinding aids of cement at all ages.
• When TIPA is added individually it does not
make significant difference in strength at 28
days.
• 1 day strength of mixture of TEA and TIPA fall
between neat TIPA and neat TEA.
• Combination of TIPA and TEA used in the
proportion 3:1 or 1:3 respectively significantly
increase the compressive strength at all ages.
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27. 0
10
20
30
40
50
60
1 day 7 day 28 day
Compressivestrength(MPa)
Age(days)
No GA addition
TIPA
TEA
TIPA:TEA=1:1
TIPA:TEA=1:3
TIPA:TEA=3:1
Fig 6.Comparison of compressive strength (MPa) by adding different GAs
and their combinations
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28. Effect of GA on Grinding Mill Output
• Grinding mill can be loaded with higher mass using grinding aids and it can
minimize power consumption.
• Table 3. Blaine values at different grinding masses and grinding energies
11-05-2015 Indian Institute of Technology,Delhi 28United states patent: 4,990,190

29. Fig 7. . % increase in bline(cm2/g)due to increase in grinding-
energy(kWh/ton)[
United states patent: 4,990,19011-05-2015 Indian Institute of Technology,Delhi 29

30. Conclusion
• Grinding aids are used to improve grinding
efficiency of the clinker particles and to
minimize the power consumption.
• Grinding aid also improve some physical and
mechanical properties of cement.
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31. References
[1] M. Katsioti,P.E. Tsakiridi,,P. Giannatos, Z. Tsibouki J.
Marinos(2008):”CHARACTERIZATION OF VARIOUS CEMENT
GRINDING AIDS AND THEIR IMPACT ON GRINDABILITY AND
CEMENT PERFORMANCE” Elsevir Publication Construction and
Building Materials
[2] Bravo Anna, Cerulli Tiziano, Giarnetti Mariagrazia, Magistri
Matteo:”GRINDING AIDS:A STUDY ON THEIR MECHANISM OF
ACTION”Mapei Publication
[3] Dr. Martin Weibel, Dr. Ratan K. Mishra(2014)“GRINDING AIDS
INCREASE THE PRODUCTIVITY AND COST-EFFECTIVENESS OF
CEMENT PRODUCTION” Sika Technology Center Zürich
[4] Davide Padovani, Matteo Magistri “IMPROVEMENT OF
MECHANICAL STRENGTHS BY THE USE OF GRINDING
AIDS:OPTIMISATION OF SULPHATE CONTENT IN CEMENT” Mapei
SpA, Italy
[5] Howard II. Moorer ,Charleston; Charles M. Anderegg(1971):UNITED
STATES PATENT 13,615,785
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32. [6] David F. Myers, Columbia; Ellis M. Gartner(1991): UNITED STATES
PATENT 4,990,190
[7] Preston L. Veltman(1967):” MINERAL GRINDING AIDS AND PROCESS
OF GRINDING”UNITED STATES PATENT 33125305
[8] D.W.Fuestenau(1995):”GRINDING AIDS” Kona Powder and Particle
Journal
[9] Joseph J. Assaad, Salim E. Asseily,Jacques Harb(2008): EFFECT OF
SPECIfiC ENERGY CONSUMPTION ON fiNENESS OF PORTLAND
CEMENT INCORPORATING AMINE OR GLYCOL-BASED GRINDING
AIDS” RILEM Publication
[10]V.S. Ramachandran(1976):”HYDRATION OF CEMENT-ROLE
OFTRIETHANOLAMINE” Cement and Concrete Research.Vol.6, 1976
[11] Z. Heren and H.Olmez(1996):
”THE INFLUENCE OF ETHANOLAMINES ON THE HYDRATION AND
MECHANICAL PROPERTIES OF PORTLAND CEMENT” Cement and
Concrete Research.Vol.26,1996
[12] Alejandro Pérez-Velázquez:’’ LOW COST GRINDING AIDS FOR
CEMENT’’worldcements.com
11-05-2015 Indian Institute of Technology,Delhi 32