New Journal of Glass and Ceramics, 2011, 1, 119-124
doi:10.4236/njgc.2011.13017 Published Online October 2011 (http://www.SciRP.org/journal/njgc)
119
Compressive Strength and Electron
Paramagnetic Resonance Studies on
Waste Glass Admixtured Cement
Ramasamy Gopalakrishnan1, Dharshnamoorthy Govindarajan2
1Department of Physics, SRM University, Kattankulathur, India; 2Department of Physics, Annamalai University, Annamalai Nagar,
India.
Received July 22th, 2011; revised August 28th, 2011; accepted September 7th, 2011.
ABSTRACT
The present work reports the effect of waste glass (WG) on the properties of Portland cement through Electron Para-
magnetic Resonance (EPR) study. Cement pastes containing 0, 10, and 30% replacement of waste glass with cement
and in a water to cement ratio of 0.4 have been prepared. The g factors of Fe(III) and Mn(II) impurities at different
hydration ages ha ve been calculated. The decreased gFe values and simultaneous increase in g Mn valu es with increase in
replacement % of WG are explained due to retardation of cement hydration.
Keywords: EPR, Cement, Waste Glass, Setting Time, Compressive Strength, G-Factor
1. Introduction
Cement is an important adhesive used by mankind in all
walks of life, ri ght from filling the teeth cavity to th e Sky-
Scrapers. Clinker, produced by heating a mixture of
limestone and clays at 1500˚C, is composed of various
calcium minerals, e.g. calcium silicates, aluminates and
ferrites. The principle minerals are tricalcium silicate
(C3S), dicalcium silicate (C2S), tricalcium aluminate
(C3A) and tetracalcium aluminoferrite (C4AF) [1]. Hy-
dration products, formed when cement or clinker miner-
als are mixed with specific amount of water, have
chemical and physiccal properties that vary with the con-
ditions of hydration (time, temperatures, pressure etc.,).
The hydration products of cement form a colloidal struc-
ture (hydrogel), when cement is hydrated with much ex-
cess water. There are many methods, which can be used
to analyze the succeeding mechanisms in the cement
hydration. They are FTIR, XRD, DTA, SEM, Electrical
measurement and dielectric methods [2-6].
The utilization of many industrial byproducts in the
construction industry is now well developed as it help s in
improving the sustainability in two ways. First, reuse of
and will be occupying scarce land resource. Second, it
minimizes the degradation of land and the environment
as a result of comparatively less digging. “Recycling” is
an All-Prevailing practice now as it conserves the planet’s
resources. The construction industry has shown great
gains in recycling industrial by products and waste, in-
cluding waste glass ( WG).
Glass is produced in many forms including packaging
or container glass (bottles and jars), flat glass (windows
and windscreens), bulb glass (TV screens, monitors etc.),
all of which have a limited life in the form they are pro-
duced and need to be reused/recycled to avoid environ-
mental problems that would be created if they were to be
stockpiled or send to landfill. The finely ground waste
glass is a mineral additive in cement is another promising
direction for waste glass recycling.
The use of recycled waste glass in Portland cement has
attracted a lot of interest worldwide due to the increased
disposal costs and environmental concerns. Being amor-
phous and containing relatively large quantities of silicon,
aluminium, calcium, glass is, in theory, pozzolanic or even
cementitious in nature when it is finely ground. Thus, it
can be used as a cement replacement in Portland cement.
Recently, many studies have focused on the uses of was-
tes glasses as aggregates for cement concrete or as ce-
ment replacement [7-9]. Recently some attempts have
been made to use the waste glasses as raw siliceous
materials for the production of Portland cement [10-12].
Studies have been done on the possibility of reusing
waste glasses as asphalt additive or rode filler [13].
Electron Paramagnetic Resonance (EPR) is an ideal

Compressive Strength and Ele c tron Paramagnetic Resonance Studies on Waste Glass Admixtured Cement
120
complementary technique for other methods in a wide
range of studies in the area of chemistry, biology, medi-
cine and physics. EPR spectroscopy offers information
on the equilibrium structure as well as the dyn amic prop-
erties (dynamic or time dependent Hamiltonian) of sys-
tem containing one or more unpaired electrons. EPR has
been successfully applied to hydration of waste glass
admixtured cement paste, following the behaviors of iron
and manganese ions. According to Bruckner et al. [14],
EPR and Mossbauer investigations confirm that in addi-
tion to oxygen, the internal cement components such as
Fe(III) and Mn(III) act as oxidizing agents being reduced
to Fe(II) and Mn ( II) ion s resp ectiv ely. From X- ban d EPR
spectra of unhydrated cement, Lubomir Lapcik and Zden ek
Simek [15] have suggested that iron is mainly Fe(III),
which is in a tetragonally distorted octahedral symme-
try, due to th e surroun ding liga nds. As fa r as we are aw a-
re, EPR studies on hydration of cement are meager and
no EPR studies have been reported so far on hydration of
soda-lime waste glass admixtured cement paste. The pur-
pose of this paper is to present a detailed EPR study on
soda-lime waste glass admixtured cement paste hydrated
for differe nt inter vals o f time.
2. Materials and Methods
2.1. Experimental Methods
Initial setting time and final setting time has been meas-
ured on OPC and WG admixtured cement paste in a wa-
ter to cement ratio of 0.4 [17] and reported in Table 2.
Compressive strength has been measured on OPC and
WG admixtured cement in a water to cement ratio of 0.4
and sand: cement ratio of 1:3 [17]. The proportions of the
cement, sand and water were calculated according to In-
di an standard (IS No. 650 - 1960). The standard size buil d-
ing sand was used. The mixtures were filled into 7 × 7 × 7
cm cubes tightly and were allowed to dry and then cured.
After 1 day, 1 week and 4 weeks, the cubes were split
open and subjected to compression testing, which the av-
erage of three cubes and the results are shown in Table 3.
EPR spectra are recorded using JEOL JES-TE100 ESR
Spectrometer operating at X-band frequencies, having a
100 KHz field modulation. DPPH is used as the standard
reference for magnetic field correction. For all samples
the experimental parameters are the same and g-values
are obtained from the equation g = h/B, wh ere  is the
Bohr magneton, h is the Planck’s constant,  is the fre-
quency and B is the center field at which the resonance
occurred [18]. The g-value is the key parameter in iden-
tifying paramagnetic results in a particular symmetry.
2.2. Materials
In the present study, the commercial available Ordinary
Portland Cement (OPC) and soda lime Waste glass were
used. Waste glasses are grinded in laboratory for 5 h.
Before grinding, bottles were crushed by a hammer to
gr anulate it. The chemical properties of cement and Waste
glass are given in Table 1. From the chemical analysis,
the OPC and WG contain small amounts of iron and
manganese and are in the oxidation state of + 3.
2.3. Sample Preparation
Present investigation, Ordinary Portland cement and Waste
glass admixtured cement paste was prepared by mixing
double distilled water in water to cement ratio (W/C) of
Table 1. Oxide Composition (%) of Ordinary Portland ce-
ment and Waste Glass.
Constituents Oxide
Composition (%)
Cement
Oxide
Composition (%)
Waste glass
CaO 63.32 12.89
SiO2 21.70 70.40
Al2O3 5.40 1.98
Fe2O3 3.40 1.41
MgO 2.09 0.87
SO3 2.10 -
MnO 0.12 0.97
Na2O nil 12.90
K2O nil 0.85
Loss on ignition 0.79 0.54
Insoluble residue1.08 0.19
Table 2. Setting time of Waste glass admixtured cement
paste.
Sample Initial setting time
hr.min Final setting time hr.min
OPC + 0% WG 5.05 6.50
OPC + 10% WG 5.20 7.15
OPC + 30% WG 5.55 8.05
Table 3. Compressive strength (MPa) of Waste glass ad-
mixtured cement.
Sample 1 day 1 week 4 weeks
OPC + 0% WG 10.4 32.6 47.7
OPC + 10% WG 8.7 31.2 45.4
OPC + 30% WG 7.1 28.3 46.7

Compressive Strength and Ele c tron Paramagnetic Resonance Studies on Waste Glass Admixtured Cement
121
0.4. OPC is partially replaced with 0%, 10% and 30% of
WG by weight. The samples were thorough ly mixed w ith
water using a glass rod for two minutes and then allowed
to hydrate in Air-Tight plastic containers. Samples hy-
drated for periods 1 hour, 1 day, 1 week and 4 weeks
were subjected to acetone. To remove water content the
hydrated samples were Oven-Dried at 105˚C for 1 hour
[16]. The samples hydrated more than 1 day were cured.
The dried samples were powdered using agate mortar
and used EPR methods.
3. Results and Discussion
The Electron Paramagnetic Resonance spectrum of an-
hydrous cement and powdered waste glass are shown in
Figure 1.
From the Figure 1(a), the broad and strong EPR signal
at g = 4.13 pertains to the Fe(III) ion, which is in a tetra-
gonally distorted octahedral environment, surrounded by
six ligands [15]. The spectrum consists of a sextet having
a g-value of 2.14 and a hyperfine coupling constant of
9.1 mT is also present. This is owing to Mn(II), replacing
Ca(II) ions in the lattice positions of calcium hydroxide.
The observed values in the present work also agree with
those reported by Bruckner et al., [14].
Figure 1. EPR spectra of anhydrous a) Cement (Frequency
= 9.39624 GHz) and b) Waste glass powder (Frequency =
9.39729 GHz).
The EPR spectrum of anhydrous WG powder [Figure
1(b)], the broad and strong EPR signal at g = 4.21 per-
tains to the Fe(III) ion which is generally present in
glasses. In addition, a six peak spectrum observed and
having a g-value of 2.16 indicates the characteristics of
to Mn(II) impurity. In both these spectra, the Fe(III) sig-
nal at g  2 is superimposed by a hyperfine spiliting sex-
tet arising from manganese ions, which is due to the
population of another Kramer’s doublet [19].
Figures 2 - 4 shows the EPR spectra of hydrated ce-
ment paste and WG admixtured cement paste (10% &
30%) at various time intervals viz., 1 hour, 1 day, 1 week,
4 weeks. In order to have a better view in the changes of
g-values, the g-values have been plotted as a function of
WG admixtured cement for Fe(III) and Mn(II) and
shown in Figures 5 and 6 respectively.
For hydrated cement paste (Figure 2), both gFe and gMn
values are found to higher at 1 hour when compared to
anhydrous. When cement mixed with water, immediately
due to dissolution of the hydroxyl (OH-) and Calcium
(Ca2+) ions concentration increases. C3A and C4AF are
responsible for the setting of cement and its containing
aluminate and ferrite phases having high amount of iron
and also some miner elements soluted in the structure.
Ettringite (AFt) is the first hydration products in cement,
Figure 2. EPR spectra of OPC paste hydrated with (a) 1
hour (Frequency = 9.39723 GHz) (b) 1 day (Frequency =
9.37654 GHz) (c) 1 week (Frequency = 9.39465 GHz) (d) 4
weeks (Frequency = 9.39873 GHz).
rich in iron content, produced through the consumption
of gypsum by C3A. The reaction of C3A be represented
by the following equation [20].




23426 242
312
3CaO.A lO3CaSO32HOCaAlSOOH.26 HO
Tricalcium gypsum water ettringite
Aluminate (1)

Compressive Strength and Ele c tron Paramagnetic Resonance Studies on Waste Glass Admixtured Cement
122
Fi gure 3. EPR spectra of OPC + 10% WG admixtured paste
hydrated with (a) 1 hour (Frequency = 9.39428 GHz) (b) 1
day (Frequency = 9.39566 GHz) (c) 1 week (Frequency =
9.39728 GHz) (d) 4 weeks (Frequency = 9.39874 GHz).
Figure 4. EPR spectra of OPC + 30% WG admixtured
paste hydrated with (a) 1 hour (Frequency = 9.39537 GHz)
(b) 1 day (Frequency = 9.39 584 GHz) (c) 1w eek (Frequency =
9.39734 GHz) (d) 4 weeks (Frequency = 9.39790 GHz).
3.95
4
4.05
4.1
4.15
4.2
1 hour 1 day1 week4 weeks
Hydrat ion time
g
Fe
OPC+0% WG
O P C + 10% W G
O P C+30% WG
Figure 5. gFe values Vs hydration of waste glass admixture
cement paste.
1.9
2
2.1
2.2
2.3
1 hour 1 day1 week4 week s
Hydration t ime
g
Mn
OPC+0% WG
OP C +10% WG
O P C+ 30% WG
Figure 6. gMn values Vs hydration of waste glass admixtured
cement paste.
Due to increase in iron content (AFt), the resonance
line due to Fe(III) species becomes broader and distrib-
uted over the whole range of spectrum. The broad signal
is attributed to magnetically ordered Fe-O-Fe species
with Ferri/Ferro or antiferro magnetic behaviour. The
high gFe value (4.17) of the OPC paste is caused by Fe(III)
ions in sites of strong rhombic distortion [21].
From the Figure 2(a), the observed sextet at gMn =
2.20 is due to Mn(II) impurity ions and incorporated into
Ca lattice positions of Ca(OH)2. The gMn values gradually
increases up to 1 day due to less incorporation of formed
Mn(II) in Ca(OH)2.[14]. Since before 1 day the forma-
tion of Ca( OH )2 is very less.
At 1 day, the Ca(II) concentration reaches the satura-
tion level and the crystallization of calcium hydroxide
occurs and C-S-H gel is formed moreover the availability
of ions and water is also reduced. The formation of C-S-
H and Ca(OH)2 is represented by the following equations



2222 2
23CaO.SiO + 6HO3CaO.2SiO.3HO+ 3CaOH →
Tricalcium water C-S-H Calcium hydroxide
Silicate (2)




2222 2
22CaO.SiO 4HO3CaO.2SiO.3HO CaOH
Dicalcium water C-S-H Calcium hydroxide
Silicate (3)

Compressive Strength and Ele c tron Paramagnetic Resonance Studies on Waste Glass Admixtured Cement123
The C-S-H gel is one of the major strength rendering
components of the hydrated cement and it possesses
sparse dispersibility, numerous interior structural effects
and coarse particle surfaces. After 1 day, the availability
of Fe(III) and Mn(II) ions are reduced and hence the g-
values have gradually decreased. This is because these
two ions in cements are responsible for the kinetics of
solidification and hardening of the main silicate compo-
nent. This may b e that the mobility of this particular sili-
cate aggregate is reflected in the vigorous changes in
polycrystalline quasi-isotropic character of electron
paramagnetic spectra of Fe(III), Fe(II) ions to the anisot-
ropic [15]. Also the decreased g-factor values reflect the
structural changes of Fe(III) ions to Fe(II) ions. These
characteristics generally decrease the g-values of Fe and
Mn but increase the strength of cement up to 4 weeks.
From the Figures 3 and 4, it is observed that WG ad-
mixtured cement also follows the same fashion as that of
OPC. In WG admixtured cement paste exhibit a lower gFe
then that of the plain cement paste, the lowest being ob-
served for the mixture with the highest amount of WG
(30%). This is due to well kno wn retarding effect of WG.
The WG admixtured cement showed longer setting times
than the pure cement. Since, as the increase of WG con-
tent reduces the cement in the mix (cement dilution). As
a result, hydration process slows down and hence the
volume of hydration products is less causing settin g time
to increase.
At all hydration periods, the WG admixtured cement
paste shows higher gMn values than the plain cement
paste. This is attributed to the red uction in the amount of
Ca(OH)2 retarded by the clinker phases because of the
reduced cement content, leading to less incorporation of
formed Mn(II) in Ca(OH)2. This effect is reflected in
EPR spectrum (Figure 3 and 4) that as replacement % of
WG increase in cement, the intensity of the Mn(II) signal
is also increases.
Table 3 depicts the compressive strength of waste
glass powder modified cement pastes at different hy-
drated period. The compressive strength decrease with
increase in WG powder contents, the reason being the
reduction in cement content and increase porosity. At
early age no secondary growth of C-S-H gel, because of
the poor pozzolanic reaction between Ca(OH)2 and WG.
4. Conclusions
The effect of Waste glass powder on the proper ties of Port-
land cement is studied through Electron Paramagnetic
Resonance with different hydrated periods. The follow-
ing conclusions emerge:
1) The results indicate that EPR studies can be effect-
tively used as a powerful tool in delineating the com-
plexities of chemical reactions in cement hydration and
to detect very small concentrations of Fe(III) and Mn(II)
ions present in cement.
2) Setting time and compressive strength results is a
confirmation of the retarding effect of WG in the hydra-
tion of the Portland cement.
3) The use WG for cement makes it possible to solve
some environmental problems well but it may be consid-
ered after studying about its long term reactions, shrink-
age properties, Alkali-Silica reaction, Porosity and adhe-
sive capacity.
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Cement nomenclature: C = CaO; S = SiO2; H = H2O;
C3S = 3CaO.SiO2; C2S = 2CaO.SiO2; C3A = 3CaO.Al2O3;
C4AF = 4CaO.Al2O3.Fe2O3; CH = Ca(OH)2