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Frontiers in Science

p-ISSN: 2166-6083    e-ISSN: 2166-6113

2011;  1(1): 21-27

doi: 10.5923/j.fs.20110101.04


SPECTROSCOPIC STUDIES ON INDIAN PORTLAND CEMENT HYDRATED WITH DISTILLED WATER
AND SEA WATER

 * Abstract
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D. Govindarajan 1, R. Gopalakrishnan 2



1Department of Physics, Annamalai University, AnnamalaiNagar, 608002, India

2Department of Physics, SRM University, SRM Nagar, 603203, India





Correspondence to: R. Gopalakrishnan , Department of Physics, SRM University,
SRM Nagar, 603203, India.

Email:






Copyright © 2012 Scientific & Academic Publishing. All Rights Reserved.



Abstract

The spectroscopicstudies have been carried out for Indian Portland cement
hydrated with distilled and sea water in a water to cement ratio of 0.4. This
study aims to analyze the effect of water on Portland cement. FTIR, DTA, XRD and
EPR studies were used to characterize the hydration reaction of the cement
pastes. Experimental results on setting time, compressive strength are also
reported. The unreacted clinker phases and g-factors are calculated. The results
indicate that sea water accelerates the cement hydration at early stage but
retards in the latter stage of hydration.



Keywords: Spectroscopic Studies, Cement, Waters, Setting Time, Compressive
Strength



Cite this paper: D. Govindarajan , R. Gopalakrishnan , "Spectroscopic Studies on
Indian Portland Cement Hydrated with Distilled Water and Sea Water", Frontiers
in Science, Vol. 1 No. 1, 2011, pp. 21-27. doi: 10.5923/j.fs.20110101.04.


ARTICLE OUTLINE

1. Introduction2. Materials and Methods3. Results and Discussion    3.1. FTIR
Results    3.2. DTA Results    3.3. XRD Results    3.4. EPR Results     3.5.
Setting Time and Compressive Strength Results4. Conclusions



1. INTRODUCTION

Portland cement is a heterogeneous fine grained material consists of four main
solid phases namely Tricalcium Silicate (C3S), Dicalcium Silicate (C2S),
Tricalcium Aluminate (C3A), TetracalciumAlumino Ferrite (C4AF). During hydration
of cement, Calcium Silicate Hydrate (C-S-H) gel and calcium hydroxide (Ca(OH)2)
are formed from silicates phases and ettringite (AFt), monosulphate (AFm) are
formed from aluminate phases[1]. C-S-H, a major hydration product is the main
strength forming phase in the cement paste. Ca(OH)2 is a crystalline,
isostructural with natural mineral of Portlandite. The cement hydration
reactions are

(1)

(2)

(3)

(4)

Many Spectroscopic methods, Setting time and Com- pressive strength have been
used in various studies of cement hydration for a number of years[2-5].Cement
notations: C = CaO; S = SiO2; H = H2O; C3S =3CaO.SiO2; C2S = 2CaO.SiO2; C3A =
3CaO.Al2O3; C4AF = 4CaO.Al2O3.Fe2O3; CH = Ca(OH)2Presently, all over the world,
the construction of buildings near sea shores are increased in numbers due to
Tsunami. Moreover, the intrusions of sea water range in the earth are also
increases in several kilometres. Hence the urge for more research work on
behavior of sea water treated cement is needed. The influence of different
waters on cement was studied by Barathan et al.,[6] with the help of X-band
Microwave technique. They have reported that the cement mixing with sea water
has the highest value of ε and σand then ground water and then distilled water.
Ghorabet al.,[7] pointed that the sea water accelerates cement hydration due to
the chloride ions and hence early setting. Ganjian and Pouya[8] and Kaushik and
Islam[9] states that the sea water initially accelerate the cement hydration and
hence an early strength. Huseyin Yigiter et al.,[10] was investigated the
effects of cement type, cement content and water to cement ratio level on the
sea water resistance of concrete. According to Manu Santhanam et al.,[11]
microstructure and thermal analysis investigation confirm that sulfate attack in
Portland cement mortars performed better in seawater solution compared to ground
water solution.As far as we are aware, spectroscopic studies on hydration of
Indian cement with distilled water and sea water are less and especially no EPR
studies on hydration of cement treated with sea water. In this study, the author
discusses the results obtained from spectroscopic studies on Indian cement
treated with distilled water (DW and sea water (SW) at different hydration time
intervals.


2. MATERIALS AND METHODS

Table 1. Content of solvents of different waters (μg/g)

WaterTotal dissolved solventsTotal
hardnessChlorineMagnesiumCalciumSulphurSodiumDW45412SW3050010601640010802725.809100

A commercial Portland cement (PC) was used and subjected to chemical analysis
using standard procedure suggested by ASTM and found the ingredients in percent
as follows: CaO 63.32; SiO2 21.70; Al2O3 5.40; Fe2O3 3.40; MgO 2.09; MnO 0.12;
SO3 2.10; Loss on ignition 0.79 and Insoluble residue 1.08. The distilled water
and sea water was analyzed using standard procedure and given in Table 1.The
pastes were prepared by mixing the cement with distilled water and sea water in
water to cement ratio of 0.4. The samples were thoroughly mixed using glass rod
for two minutes and then allowed to hydrate in air-tight plastic containers. The
hydrations were stopped at different time intervals viz., 1 hour, 1 day, 1 week
and 4 weeks by a consecutive soaking in acetone. To remove water content the
hydrated cement pastes were oven-dried at 105℃ for 1 hour[12]. The samples
hydrated for more than 1 day were cured properly. The dried samples were
powdered using agate mortar for FTIR, DTA, XRD and EPR studies.The Fourier
transform infrared measurements were recorded with a Nicolet-Avatar 360 model
FTIR spectrometer using the KBr pellets technique. The Thermal curves of the OPC
pastes were taken in a Perkin Elmer thermal analyzer. A total of 10-15 mg of the
samples was heated in a platinum crucible in air atmosphere up to 1000℃ in a
heating rate of 10℃/min. Compositional changes occur in the hydrated OPC pastes
were identified by X-ray diffraction with CuKα radiation for Bragg’s angles
between 5 and 70 with the scan rate of 0.1 to 120 degrees in 2θ/min. EPR spectra
were recorded using JEOL JES-TE100 ESR Spectrometer operating at X-band
frequencies, having a 100 KHz field modulation and DPPH is used as the standard
reference for magnetic field correction. Setting time has been measured on DW
and SW cement paste and compressive strength of the cement with DW and SW at
different hydration times period were determined[13] and reported in Table 2.

Table 2. Setting time and Compressive strength of cement treated with DW and SW

SampleWaterSetting time (h:min)Compressive strength (MPa)InitialFinal1 day1
week4 weeksOPCDW SW5.054.106.506.2010.413.132.634.447.733.1


3. RESULTS AND DISCUSSION

3.1. FTIR RESULTS

The FTIR spectrum of the anhydrous Portland cement Fig. 1(a) shows a sharp band
at 3630 cm-1 associated to O-H stretching vibrations of portlandite (Ca(OH)2)
and the peaks at 3410 and 1610 cm-1 are correspond to stretching and bending
modes of water of crystallization particularly from gypsum. The carbonates peak
at 1425 cm-1, 717 cm-1 and 875 cm-1 are observed due to the reactions of
atmospheric CO2with calcium hydroxide. The triplet bands appearing at 1100-1160
cm-1 are due to ν3 modes of and the week bands at 659 cm-1 and 600 cm-1 are due
to ν4 modes of. The strong band at 919 cm-1 is due to Si-O asymmetric stretching
vibration of C3S and/or C2S.Out of plane Si-O bending (ν4) and in-plane Si-O
bending (ν2) are observed at 525 cm-1 and 455 cm-1 respectively. The band
assignments are in good agreement with those reported in the previous
studies[14-16].

Figure 1. FTIR spectra of (a) Anhydrous cement and Distilled water hydrated
cement paste at (b) 1hour (c) 1 day (d) 1 week (e) 4 weeks

From the FTIR spectra of DW treated cement paste (Fig. 1(b-e)), as hydration
progresses, the following bands are observed i) the intensity of the band at
3630 cm-1 increases indicating liberation of more Ca(OH)2. ii) the broad band at
3440 cm-1 are intensified with hydration, indicating that the increase of
hydrated products associated with water. iii) the strong asymmetric stretching
Si-O band (ν3) is shifted to high frequencies centered at 970 cm-1 with
hydration indicates that the formation of C-S-H[17]. The decrease and increase
in intensities of the out-of-plane and in-plane Si-O bending vibrations are
occur in significant changes with hydration and it indicates that the
polymerization of units in cement.For sea water treated cement pastes (Fig. 2),
the same frequency assignment holds good as that of DW, but there is variation
in intensities are observed. The shifting of ν3 Si-O band and variation in
intensity of ν4 and ν2 Si-O bands are enhanced by SW are observed in early age.
Up to 1 week, the intense sulfate band () at 1100-1160 cm-1 are observed and it
implies that SW enhance the AFt formation than DW. The observed variation in
intensities of the band at 919-970 cm-1, 525 cm-1 and 455 cm-1 are higher and
occur from early age onwards. This indicates that the initial reactions are
faster due to the higher amount of chloride and sulfate ions present in the sea
water[6,7]. At 4 weeks, the intensity of the band observed at 970 cm-1, 525 cm-1
and 455 cm-1 are less when compared to 1 week hydration. This may be due to
disappearance of mineral contents in sea water. The above fact that increases
the strength up to 1 week and slightly decreases at 4 weeks. Hence it is clear
that SW accelerate the cement hydration at early stage but in latter stage
slightly retarded.

Figure 2. FTIR spectra of Sea water hydrated cement paste at (a) 1hour (b) 1 day
(c) 1 week (d) 4 weeks

Figure 3. DTA curves of Distilled water hydrated cement paste at (a) 1hour (b) 1
day (c) 1week (d) 4 weeks

3.2. DTA RESULTS

Fig. 3 shows the DTA thermograms of OPC treated with DW at different hydration
periods. At 1 hour hydrated cement paste, five endothermic peaks are observed.
The peak at 98℃ and 160℃ are due to the presence of gypsum. The endothermic peak
observed at 130℃ represents decomposition of ettringite. The fourth peak at 450℃
represents the decomposition of calcium hydroxide. The fifth endothermic peak at
670℃ is due to decomposition of calcium carbonate[18]. At 1 day, the peak at 98℃
and 160℃ are disappearing. This implies that the reaction of gypsum is almost
exhausted. Further at 1 day, endothermic curve appears at around 115℃ and 180℃
indicates the formation of C-S-H and monosulphate. With progress of hydration,
the endotherms due to C-S-H, monosulphate and Ca(OH)2 are increased in size
(Fig. 3) are observed and also slightly shifting to a higher temperature. At 4
weeks, the intensity of the calcium carbonate endotherm is decreased. This is
due to the reaction of CO2with C-S-H and Ca(OH)2 according to the following
equation:[17]

(5)

(6)

The main features of the SW treated paste (Fig. 4) when compared to DW treated
paste are i) the peak intensities are increases and slightly shifts to higher
temperature up to 1 week due to the presence of mineral ions. ii) At 4 weeks,
peak intensities are decreased due to the disappearance of mineral ions. These
findings are totally agreed with FTIR results.

Figure 4. DTA curves of Sea water hydrated cement paste at (a) 1hour (b) 1 day
(c) 1 week (d) 4 weeks

3.3. XRD RESULTS

Fig. 5(a) shows the XRD pattern of anhydrous cement. The spectrum indicated the
presence of gypsum (2θ = 11.70), tricalcium silicate (2θ = 32.20, 51.50, 62.40),
dicalcium silicate (2θ = 32.50, 56.15), tricalcium aluminate (2θ = 26.51),
tetracalciumaluminoferrite (2θ = 44.10) and CaO (2θ = 37.60) respectively are
coincide with previous reports[19-21].The XRD patterns of the cement hydrated
with DW at 1 hour, 1 day, 1 week and 4 weeks are shown in Fig. 5(b-e).At 1 hour,
ettringite (2θ = 9.10, 23.10, 41.25) and Ca(OH)2(2θ = 18.10, 33.57) crystallized
phases are observed. At 1 day hydrationC-S-H (2θ = 29.50) and monosulphate (2θ =
56.64) phases are identified. The four clinker phases (C3S, C2S, C3A, C4AF)
decreases with increasing hydration time and consequently C-S-H, Ca(OH)2
crystalline phase intensities are increases. The CaCO3(2θ = 38.68) peak is
observed for all hydration time, due to the atmospheric carbon dioxide during
grinding and preparation of samples[22].These results are confirmed through
FTIR, DTA.

Figure 5. XRD pattern of (a) Anhydrous cement and Distilled water hydrated
cement paste at (b) 1hour (c) 1 day (d) 1 week (e) 4 weeks

The XRD pattern of SW treated cement pastes at various hydration time intervals
are shown in Fig. 6. The products formed in SW treated cement are similar to
that of DW treated cement, but higher amount of ettringite are observed in the
initial stage. The rate of increase of C-S-H and Ca(OH)2intensities and the
corresponding decrease of C3S and C2S intensities are higher when compared to DW
treated cement. This is due to the presence of mineral ions and hence
accelerates the hydration.

Figure 6. XRD pattern of Sea water hydrated cement paste at (a) 1hour (b) 1 day
(c) 1 week (d) 4 weeks

The percentage of unreacted cement clinker (C3S (2θ = 32.2), C2S (2θ = 32.5)),in
different hydration time intervals for DW, SW treated pastes were evaluated
according to the method described by Montgomery etal.,[23].The results are given
in Table 3.

Table 3. The percentages of unreacted cement clinker (C3S, C2S) remaining in
hydrated cement treated with DW and SW

Hydration PeriodC3SC2SDWSWDWSW1 hour85.4074.2189.2177.241
day69.4567.4575.2471.21 1 week42.2340.4557.4054.51 4 weeks19.3222.4518.3421.45

The results shows that the % of unreacted C3S and C2S are decreases in DW
treated cement with hydration time and this value in the present work are agreed
with those reported by[17].For SW treated cement, the rate of decrease in
percentage of unreacted C3S are higher up to 1 week when compared to DW cement
paste but at 4 weeks the rate of decrease of percentage of unreacted C3S and C2S
arelower. This trend shows at the well evidence for SW accelerate the cement
hydration in the early stage and retard in the latter stage.

3.4. EPR RESULTS

The EPR spectra OPC paste mixing with DW and SW is shown in Figs. 7 and 8.For
all samples the experimental parameters are the same and g-values are obtained
from the equation g = hν/βB, where β is the Bohr magneton, h is the Planck’s
constant, ν is the frequency and B is the center field at which the resonance
occurred[24]. The g-value is main key parameter in identifying paramagnetic
results in a particular symmetry. The g-values have been calculated for both
Fe(III) and Mn(II) signals of cement pastes at different hydration period and
are shown in Figs. 9 and 10(Table 4).

Figure 7. EPR spectra of (a) Anhydrous cement (Frequency = 9.39624 GHz) and
Distilled water hydrated cement paste at (b) 1hour (Frequency = 9.39723 GHz) (c)
1 day (Frequency = 9.37654 GHz) (d) 1 week (Frequency = 9.39465 GHz) (e) 4 weeks
(Frequency = 9.39873 GHz)

Figure 8. EPR spectra of Sea water hydrated cement paste at (a) 1hour (Frequency
= 9.39812 GHz) (b) 1 day (Frequency = 9.37731 GHz) (c) 1week (Frequency =
9.39654 GHz) (d) 4 weeks (Frequency = 9.39751 GHz)

Figure 9. gFe values vs hydration time of cement paste treated with DW and SW

Figure 10. gMn values vs hydration time of cement paste treated with DW and SW

Table 4. g-values of the cement paste treated with DW and SW

Hydration PeriodgFegMnDWSWDWSWAnhydrous4.134.132.142.141 hour4.154.172.202.191
day4.174.192.192.171 week4.094.122.122.104 weeks4.014.012.072.04

From the anhydrous cement (Fig. 7(a)), the broad and intense EPR signal at g =
4.13 pertains to the Fe(III) ion, which is usually present in cement.This signal
arises from oxidation state of Fe(III), which is in a tetragonally distorted
octahedral environment, surrounded by six ligands. In addition, a sextet having
a g-value of 2.14 and a hyperfine coupling constant of 9.1 mT is also present.
This is due 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.[24].For DW hydrated cement paste, both gFe and gMn
values are found to increase from anhydrous cement to 1 day hydrated cement.
During hydration, ettringite is the first hydration products in cement paste,
rich in iron content, produced through the consumption of gypsum by C3A and
C4AF. Due to increase in iron content, the resonance line due to Fe(III) species
becomes broader and distributed over the whole range of spectrum. The broad
signal is attributed to magnetically ordered Fe-O-Fe species with ferri/ferro,
or anti ferromagnetic behavior. The high gFe(=4.17) value of the OPC paste is
caused by Fe(III) ions in sites of strong rhombic distortion[24]. From Fig. 7,
the observed sextet (gMn = 2.14) is due to Mn(II)impurity ions and incorporated
into Ca lattice positions of Ca(OH)2 formed during hydration[3]. The gMn values
gradually increases up to 1 day due to less incorporation of formed Mn(II) in
Ca(OH)2. Since before 1 day the formation of Ca(OH)2 isvery less. At 1 day, the
Ca(II) concentration reaches the saturation level and the crystallization of
calcium hydroxide occurs and C-S-H gel is formed and the availability of ions
and water is reduced. Hence after 1 day, the g-factor for Fe and Mn values has
gradually decreased. This is because these two ions are responsible for the
hardening of the main silicate component. It may be that the mobility ofthis
particular silicate aggregate is reflected in the vigorous changes in
polycrystalline quasi-isotropic character of electron paramagnetic spectra of
Fe(III), Fe(II)ions to the anisotropic. Also the decreased g-factor values
reflect the structural changes of Fe(III) ions to Fe(II) ions. This structural
change has affected the spin Hamiltonian parameters[23,26].The availability of
Fe(III) ions and Mn(II) ions are reduced and hence the g-factor values have
gradually decreased on standing up to 4 weeks. Due to accelerating nature of SW,
the gFe values are higher at 1 hour onwards when compared to DW. The formation
of the Ca(OH)2 starts at early stage and the incorporation of Mn(II) ions in
Ca(OH)2 starts at 1 hour onwards and hence gMn values are gradually decreased on
standing up to 4 weeks.

3.5. SETTING TIME AND COMPRESSIVE STRENGTH RESULTS

From the Table 2, the setting time of SW treated cement paste are shorter than
those of DW treated cement paste. Moreover the sea water treated cement shows
higher strength compared to distilled water treated cement up to 1 week and at 4
weeks the compressive strength are decreased. This is because that the following
reason i) in the initial stage, sea water accelerates the reaction but in the
latter stage the reaction is slower due to reduction in chloride and sulphate
ions[6,7] ii) the reaction of C2S with sea water occurs earlier and hence in the
later stage strength decreases when compared to DW treated samples. These
results are very well agreed with FTIR, DTA and XRD.


4. CONCLUSIONS

This paper describes spectroscopic studies on Indian Portland cement mixed with
distilled and sea water. The following conclusion can be drawn from this study.
1. The results indicate that spectroscopic studies can be effectively used as a
powerful tool in delineating the complexities of chemical reactions in cement
hydration.2. The contents of mineral ions in sea water accelerate the Portland
cement hydration especially at early ages. FTIR, DTA, XRD and EPR studies
corroborated these results.3. EPR is a good tool to detect very small
concentration s of Fe(III) and Mn(II) ions present in cement. g-factor values
are confirmation of the well known accelerating effect of sea water in cement
hydration.4. The effect of sea water in cement reduces the setting time,
enhances the hydration and hence consecutive strength development at early stage
but slightly retards in latter strength.5. The utility of sea water for
preparing paste may be considered after studying about its long term reaction.
Shrinkage properties, corrosion resistance and adhesion capacity are needed to
be studied in the future.


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