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 ages.

1. 1
GRINDING AIDS FOR CEMENT
Term Paper
SHYAM R. ANANDJIWALA
1st year M.Tech, Construction Technology and Management
Indian Institute of Technology, Delhi
India.
anandjiwalashyam@gmail.com
Abstract-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 ages.
Keywords — Grinding Aids,TEA,TIPA,Grinding
effciency,Surface energy
1. INTRODUCTION
Cement is the most important construction
material. There is a demand for increase in the
cement production efficiency to decrease its
production cost. Cement production causes more
than 5% of total anthropogenic carbon dioxide
emissions. 0.825 ton CO2 is emitted per ton out of
which 0.390 ton is from fossil fuel burning.
Improvement in grinding efficiency also helps to
curb this environmental issue by reducing the
consumption of electricity.
Grinding Aids have been used since decades
for improving the cement clinker grinding
efficiency. As per the theory of rupture by Griffith,
the grinding of clinker is affected by cleavage or
microcracks or the defects present in its crystal
structure [9]. During grinding, when shear stress is
applied the stress concentration occurs at such weak
points causing rupture in the molecular bonds which
further causes cracking of the clinker and ultimately
the clinker turns into fine powder. During the
process of breaking of ionic bonds highly reactive
negative and positive charges are formed on the
fractured surface causing high surface energy on the
particle surface[1][9].Due to the formation of
electrostatic charges on the surface, agglomeration
of the particles take place leading to reduction in
the surface area and increase in energy
consumption. High surface energy can lead to “pack
set” of the solid particles. Grinding aids neutralize
the charges present over the solid surface and
reduces the energy required to initiate flow in the
cement which is called “pack set inhibition”
property[1][5][6][7].This property reduces the
tendency of solid particles to form lumps during
transportation in delivery trucks and also helps to
store cement in storage silos without agglomeration.
Grinding aids should be used cautiously as very less
surface energy can also lead highly fluid cement.
Grinding aids coat the surface of nascent
cement clinker which enables the elimination of
“coating” of finer materials on the surface of
grinding media and grinding mill walls. Grinding
aid can be used to either increase the surface area of
cement at the given production rate or it can
increase the production rate of cement with the
same surface area.
Grinding aids should be diluted in water for
quick and even circulation throughout the grinding

2. 2
mill [5]. The other reason for dilution in water is
because water is also a very good grinding aid[2].
Some of the chemicals used as the grinding aids are
polyol, ether & amines. Monoethanolamine(MEA),
Diethanolamine(DEA), Triethanolamine(TEA),
Triisopropanolamine(TIPA) are the amine based
grinding aids and Ethylene glycol(EG), Diethylene
glycol(DEG) are the glycol based grinding aids.
TEA, TIPA and DEG are commonly used grinding
aids.
2.Grinding Aid Mechanisms
According to the research byDr. Martin
Weibel and Dr. Ratan K. Mishra [3], grinding aids
work on the principle of dispersion. There are two
basic mechanisms through which dispersion can
occur between the organic molecules:(1)Gas phase
transfer (2) Surface contact transfer.
The temperature in grinding mill is generally
in the range of 80-120 °C. Alcoholswith boiling
points below grinding temperature(see Table 1)
improve grinding efficiency significantly. Due to
their high volatility they are adsorbed weakly and
can still be smelt even on cold cement. Therefore it
can be assumed that they aredispersed via gas
transfer but commercially such alcohols with low
boiling point are not used as grinding aids.
Polycarboxylate ether(PCE) are used as the
grinding aids which retain their action as plasticizer
and they are dispersed via surface contact transfer.
Most of the grinding aids in commercial use
(PG,DEG,TEA) have boiling points above the
grinding temperature(see table 1). Their vapour
pressures are low still high enough therefore they
are assumed to be dispersed through both
mechanisms i.e. gas phase transfer as well as
surface contact transfer.
Table1. Boiling points of chemicals used as
grinding aids
Chemical Boiling Point(°C)
Ethanol 78
Propylene glycol(PG) 188
Diethylene glycol(DEG) 245
Triethanolamine(TEA) 335
Grinding aids work by the reduction of
surface energy on the clinker particles[3]. This
process consist 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= - E1+ E2 + E3
If the value of surface energy of clinker covered
with grinding aid(E) is negative that means the
energy is released and the grinding aid spreads out.
So 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. Nonpolar liquids adsorb weakly on the
surface of clinker due to the poor interaction with
the clinker which can cause agglomeration of
cement particles. Grinding aids which are used
commercially consist both polar and nonpolar
functional group but molecules turn polar functional
group towards the clinker[3].
3.Effect of Grinding Aids on Cement
Composition
V.S.Ramchandran[10] conducted research
on the effect of TEA on cement composition
.Dicalciumsilicate(C2S),Tricalciumsilicate(C3S),Tri
calcium alluminate(C3A) and Tricalcium
alluminate(C3A)+gypsum(CASO4
.
2H2O). TEA
accelerate the hydration of C3A[9]. C3A hydrates to
hydrogarnet(C3AH6) before it transforms to
ettringite in absence of TEA. TEA accelerates the
formation of ettringite and as TEA increase,
conversion from ettringite to monosulphate is at
faster rate. With increase in TEA amount of heat
developed increases which is the indication of TEA
accelerating reaction between gypsum and C3A in
formation of ettringite.(see fig.1).

3. 3
TEA extends the induction period of C3S
may be by forming TEA surface complex on the
hydrating C3S [9][10]. TEA also increase the
induction period of C2S like C3S.Only difference is
the slow rate of reaction. Peak due to the C3S
formation is extended with the addition of TEA
indicates the hydration of C3S is retarded by
TEA(see fig.1). According to the conduction
calorimetric curve shown in fig.1, dual peaks appear
between when TEA is added to clinker. One of the
peak represents the acceleration of aluminates
hydration. The other peak represents hydration of
C3S.
Fig.1 Conduction calorimetric curves of cement
hydrated in the presence of TEA [10]
The discussion above helps to deduce that TEA
accelerates the aluminate phase hydration and
retards the hydration of C3S & C2S phase.
4. Effect Of Grinding Aids On Mechanical
Properties Of Cement
The basic motive of addition of grinding
aids is to improve the grinding efficiency of clinker
and to increase the ball mill output. It is seen that
grinding aids also improve the mechanical
properties of cement such as setting time, surface
area, compressive strength, mortar workability.
4.1 Setting Time
Action of TEA in hydration is not
revealed [1][2]. It is not found out whether TEA is a
retarder or an accelerator [1][2]. TEA acts as
retarder at low dosage (up to 0.5 %) but accelerates
the hydration at higher dosage [10]. High dosage
TEA can be used as an accelerator in place of
calcium chloride (CaCl2) to eliminate chloride
attack. MEA and low dosage DEA does not cause
much alteration in setting time. According to
Katsioti[1], TIPA increases both initial and final
setting time of cement due to its diffusion into pores
and cracks of clinker particles.
4.2 Surface Area
All the grinding aids increase the surface
area of cement [1][2][6][9]. Table 2 shows the data
of Blaine for reference mix, Ref. mix+ 0.08% amine
GA and Ref. mix+ 0.08% glycol base GA.
Reference mix consist 85% clinker, 10 % pozzolona
and 5 % gypsum for given specific energy
consumption in grinding mill.
Table2. values of bslaine for different specific
energy consumption[9]
Specific energy
consumption(kWh/ton)
Refere-
nce mix
0.08
%
amine
GA
0.08
%
glycol
GA
4.2 1835 1990 2375
8.4 2560 2790 2920
20.9 3665 4650 4190
29.3 3865 5340 4785
46.1 4620 6765 5455
58.7 4835 6985 6175
Fig.2 shows the graph for the comparison between
the effects of amine and glycol based grinding aids
Blaine(cm2
/g)

4. 4
over the reference mix. It is evident from the fig 2.
That when specific energy consumption of grinding
mill is low then addition of glycol based GAs
increase surface area by higher amount but at higher
specific energy consumption addition of amine
based GAs give higher surface area. Results were
similar even for addition of lower dosage of
grinding aids.
Fig 2. Comparison of % increase in surface area
(cm2
/g) due to amine & glycol grinding aids
Grinding energy affects the performance of grinding
aids. At higher grinding energy the effectiveness of
grinding aids to increase surface area of cement
increase [9].
4.3 Compressive Strength
Though addition of grinding aids is basically
for the improvement in grinding efficiency it is
observed that grinding aids can enhance the
compressive strength of cement. TIPA increase 7
days and 28 days compressive strength of cement
[1][6][9][10]. If TIPA is used more than its
optimum dosage ( 0.01-0.02 %) it can increase the
28 days compressive strength but it is uneconomical
to use. It can also decrease strength at very high
dosage. 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[9].Therefore TIPA is used with air
detraining agent at higher dosage. Effectiveness of
enhancement of strength by TIPA also depends
upon the tetra calcium aluminoferrite (C4AF)
content in clinker [6]. Fe+3
ions are produced during
the hydration of C4AF. These ions are insoluble at
high pH therefore they try to precipitate from the
solution as Fe(OH)3 gel. This gel coats the clinker
grain and retards the hydration of cement. Adding
TIPA helps in removing this coating and thereby
increasing the strength of cement. C4AF content
must not be less than 4% for the improvement in
strength using TIPA [6].
The increase in 1 day strength of cement due
to addition of TEA as grinding aid is debatable.
Some authors claim that TEA reduces compressive
strength of cement at all ages[9][10] but some
authors claim the increase in 1 day strength of
cement and decrease in later age strength[6].
Reduction in the strength due to the usage of TEA is
presumed to be because of rapid hydration at early
stage which coats hydration product around cement
grain and reduce further hydration. Coating of
hydration product with higher density also cause the
porous structure [10].
Ramachandran[10] proposed the combination
of TEA and TIPA to improve compressive strength
of cement at all ages. When TIPA is added
individually it does not make significant difference
in strength at 28 days. Individually added TEA
decreases 7 and 28 days strength.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 respectively significantly
increase the compressive strength at all ages.(fig. 3)
Fig3. Comparison of compressive strength (MPa)
by adding different GAs and their combinations
0
10
20
30
40
50
0 50 100
%increasetoreferencemix
specific energy consumption(kWh/ton)
0.08% amine
GA
0.08% glycol
GA
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

5. 5
5. Effect Of Grinding Aid On Grinding Mill
Output
Grinding mill can be loaded with higher mass
using grinding aids and power consumption can be
minimized. Using grinding energy 15 KWh/ton
reference mix gives blaine 3380 cm2
/g when mass
of the sample grinded is 5 kg. Keeping the grinding
energy same, mass of the sample inside the grinding
mill is increased and grinding is added. Adding
0.06% glycol grinding aid gives nearly same surface
area at 6.5 kg as given by reference mix at 5 kg for
15 kWh/ton (See table 3). So it can be inferred that
adding 0.06% glycol GA at 15 kWh/ton can
increase the output [(6.5-5)/5]=30%.Figure 4 gives
the % increase value in bline due to increase in
grinding energy[6].
Table 3. Blaine values at different grinding masses
and grinding energies[6]
Fig4. % increase in bline(cm2
/g)due to increase in
grinding-energy(kWh/ton)[6]
6. Conclusion
It can be deduced from the above discussion
that grinding aids are used to improve grinding
efficiency of the clinker particles. Grinding aid also
improve some physical and mechanical properties
of cement.
7. 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
0
10
20
30
40
50
15 30
%increaseinoutput
Grinding Energy(kWh/ton)
0.06% amine GA
0.06% glycol GA
Blaine(cm2
/g)
Grinding
Energy(KWh/ton)
Mass of
sample
grinded
(kg) Ref.
mix
0.06%
Amin
e GA
0.06
%
Glyc
ol
GA
15 5 3380 - -
5.5 - 3845 3630
6 - 3220 3905
6.5 - 2845 3340
30 5 4240 - -
6 - 5460 5400
7 - 4005 4635
7.5 - 3540 4120

6. 6
[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
ROLE OF TRIETHANOLA
[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
Vol. 6, pp. 623-632, 19 YDRATION OF CEMENT --