The use of (micro)-X-ray absorption spectroscopy in cement research.
ABSTRACT Long-term predictions on the mobility and the fate of radionuclides and contaminants in cementitious waste repositories require a molecular-level understanding of the geochemical immobilization processes involved. In this study, the use of X-ray absorption spectroscopy (XAS) for chemical speciation of trace elements in cementitious materials will be outlined presenting two examples relevant for nuclear waste management. The first example addresses the use of XAS on powdered cementitious materials to determine the local coordination environment of Sn(IV) bound to calcium silicate hydrates (C-S-H). Sn K-edge XAS data of Sn(IV) doped C-S-H can be rationalized by corner sharing binding of Sn octahedra to Si tetrahedra of the C-S-H structure. XAS was further applied to determine the binding mechanism of Sn(IV) in the complex cement matrix. The second example illustrates the potential of emerging synchrotron-based X-ray micro-probe techniques for elucidating the spatial distribution and the speciation of contaminants in highly heterogeneous cementitious materials at the micro-scale. Micro X-ray fluorescence (XRF) and micro-XAS investigations were carried out on Co(II) doped hardened cement paste. These preliminary investigations reveal a highly heterogeneous spatial Co distribution. The presence of a Co(II)-hydroxide-like phase Co(OH)2 and/or Co-Al layered double hydroxide (Co-Al LDH) or Co-phyllosilicate was observed. Surprisingly, some of the initial Co(II) was partially oxidized and incorporated into a Co(III)O(OH)-like phase or a Co-phyllomanganate.
- SourceAvailable from: Erich Wieland[Show abstract] [Hide abstract]
ABSTRACT: In this study synchrotron X-ray absorption spectroscopy (XAS) has been applied, an element specific technique which allows Fe-containing phases to be identified in the complex mineral mixture of hydrated cements. Several Fe species contributed to the overall Fe K-edge spectra recorded on the cement samples. In the early stage of cement hydration ferrite was the dominant Fe-containing mineral. Ferrihydrite was detected during the first hours of the hydration process. After 1 day the formation of Al- and Fe-siliceous hydrogarnet was observed, while the amount of ferrihydrite decreased. The latter finding agrees with thermodynamic modeling, which predicts the formation of Fe-siliceous hydrogarnet in Portland cement systems. The presence of Al- and Fe-containing siliceous hydrogarnet was further substantiated in the residue of hydrated cement by performing a selective dissolution procedure.Cement and Concrete Research 01/2014; 58:45–55. · 3.11 Impact Factor
The use of (micro)-X-ray absorption spectroscopy in cement research
A.M. Scheidegger*, M. Vespa, D. Grolimund, E. Wieland, M. Harfouche,
I. Bonhoure, R. Da ¨hn
Laboratory for Waste Management, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
Accepted 31 January 2006
Available online 11 April 2006
Long-term predictions on the mobility and the fate of radionuclides and contaminants in cementitious waste repositories require a
molecular-level understanding of the geochemical immobilization processes involved. In this study, the use of X-ray absorption spectros-
copy (XAS) for chemical speciation of trace elements in cementitious materials will be outlined presenting two examples relevant for
nuclear waste management. The first example addresses the use of XAS on powdered cementitious materials to determine the local coor-
dination environment of Sn(IV) bound to calcium silicate hydrates (C–S–H). Sn K-edge XAS data of Sn(IV) doped C–S–H can be ratio-
nalized by corner sharing binding of Sn octahedra to Si tetrahedra of the C–S–H structure. XAS was further applied to determine the
binding mechanism of Sn(IV) in the complex cement matrix. The second example illustrates the potential of emerging synchrotron-based
X-ray micro-probe techniques for elucidating the spatial distribution and the speciation of contaminants in highly heterogeneous cemen-
titious materials at the micro-scale. Micro X-ray fluorescence (XRF) and micro-XAS investigations were carried out on Co(II) doped
hardened cement paste. These preliminary investigations reveal a highly heterogeneous spatial Co distribution. The presence of a
Co(II)-hydroxide-like phase Co(OH)2and/or Co–Al layered double hydroxide (Co–Al LDH) or Co-phyllosilicate was observed. Surpris-
ingly, some of the initial Co(II) was partially oxidized and incorporated into a Co(III)O(OH)-like phase or a Co-phyllomanganate.
? 2006 Elsevier Ltd. All rights reserved.
The long-term immobilization and safe disposal of radio-
active and industrial wastes in landfills and deep geological
waste repositories is worldwide one of the challenging tasks
to endorse the sustainable development of modern civiliza-
tion (Spence, 1993; Agency, 1999). Although new technolo-
gies focusing on waste minimization and recycling will
undoubtedly reduce waste arising in the future, an increase
in the amounts of intractable waste will be unavoidable.
Thus, for any disposal facility, release of hazardous sub-
stances must be limited to the lowest level technically (and
economically) achievable. Furthermore, strategies are
needed to ensure the safe disposal of these waste forms to
minimize their environmental impacts (Levi et al., 1990;
The present study is focusing on the molecular-level
investigation of geochemical processes related to the
long-term fate of radioactive and industrial waste in
cement-based materials. Mixing ‘fugitive’ hazardous waste
products into a cementitious binder system improves the
stabilization and the solidification of waste materials
(Atkins et al., 1994). Consequently, the migration of
radionuclides and other heavy metals from cement-based
landfills and waste repositories into the environment can
be significantly retarded and possible impacts on the
environmental quality can be minimized. For this reason,
as well as for engineering purposes, cement-based materi-
als play an important role in multi-barrier concepts for the
safe disposal of radioactive wastes in underground
near-field material of the planned Swiss disposal cavern
for intermediate level waste consists of cement and
cementitious backfill materials. From a mineralogical
standpoint cement consists mainly of calcium (aluminium)
silicate hydrates (C(A)SH phases, ?50 wt%), portlandite
approx.90 wt% ofthe
0956-053X/$ - see front matter ? 2006 Elsevier Ltd. All rights reserved.
*Corresponding author. Tel.: +41 56 310 2184; fax: +41 56 310 4551.
E-mail address: Andre.Scheidegger@psi.ch (A.M. Scheidegger).
Waste Management 26 (2006) 699–705
(?20 wt%) and calcium aluminates (?18 wt%, namely
AFm (Al2O3–Fe2O3-mono)-type and AFt (Al2O3–Fe2O3-
tri)-type phases; compositions of calcium aluminates are
discussed in detail in Taylor (1997)). Furthermore, it con-
tains ?9 wt% minor phases (e.g., hydrotalcite, hydrogar-
net, ferrite, and phosphate minerals) that can expose
highly reactive surface sites for sorption and act as storage
minerals for waste ions.
Due to interactions with cementitious solid phases the
release of radionuclides into the surrounding geosphere
(far-field) is retarded and the maximum safety over long
time periods is provided by isolating the waste until its
activity has decayed to safe levels. Thus, an in-depth under-
standing of the immobilization processes occurring in
cementitious materials (ion exchange, adsorption, precipi-
tation, solid solution formation, etc.; Agency (1999) and
references therein) is needed. The best approach to gain
process understanding in cementitious systems is to com-
bine macroscopic experiments (e.g., batch-type sorption,
leaching, degradation and column studies) with molecu-
2. Analytical tools
A wide variety of bulk characterization techniques are
routinely employed in the field of cement research. These
techniques can reveal average compositional, chemical,
structural or morphological information of cementitious
scanning calorimetry (TG-DSC) allows the identification
of specific cement minerals based on characteristic dehy-
dration temperatures (Taylor, 1997). X-ray diffraction
(XRD) is a widely used technique in cement industry
for quality control (Struble, 1991). The Rietveld method
(Izumi, 1993) provides an efficient method for quantita-
tive phase analysis of multi-phase mixtures and is used
for quantitative clinker phase analysis (e.g., Mansoutre
and Lequex, 1996; Plo ¨tze, 2000; Scrivener et al., 2004).
The method is based on the calculation of X-ray diffrac-
tion patterns that are iteratively adjusted to measured
diffractograms by convenient variation of phase specific
parameters and phase content.
Other analytical techniques used in cement research to
gain (micro)structural information include magnetic (e.g.,
1H,27Al,29Si, and43Ca NMR; Brunet et al., 2004) and
vibrational (FTIR and Raman) spectroscopies, and image
techniques such as atomic force microscopy (AFM), trans-
mission electron microscopy (TEM), and backscattered
scanning electron (BSE) microscopy (Colombet et al.,
1998). BSE imaging is based on the spatial variation of
the electron density and allows the optical identification
of typical constituents of cement phases based on grey level
contrast and the morphology (Famy et al., 2002). When
BSE imaging is combined with energy dispersive X-ray
microanalysis (EDX), spatially-resolved quantitative infor-
mation of the chemical composition can be obtained
(Famy et al., 2002).
Surface-sensitive techniques such as X-ray photoelec-
tron spectroscopy (XPS), Auger electron spectroscopy
(AES) and secondary ion mass spectrometry (SIMS) have
been utilized for elucidating the chemical environment of
waste ions in solidified waste components (e.g., Cocke
and Mollah, 1993). In particular XPS is widely used to
investigate binding mechanisms of metal ions in cementi-
tious materials. XPS allows relatively straight-forward
analysis of the near-surface of materials. The technique uti-
lizes soft X-rays which impinge on a surface, ejecting pho-
toelectrons from valence and core levels of the surface and
near-surface atoms. Thus XPS, by measuring the binding
energy of electrons, allows elemental identification and
provides chemical information about the oxidation state
of the surface and near-surface atoms. Nevertheless, struc-
tural information gained from surface analysis techniques
such as XPS is limited. For example, structural parameters
of sorbing species such as bond lengths and the type of
atoms adjacent to the sorbing species cannot be deduced.
3. Synchrotron-based X-ray absorption spectroscopy (XAS)
in cement research
Over the past decade synchrotron light sources have had
a major impact exploring chemical processes in natural and
engineered material systems and will, in all likelihood, con-
tinue to grow in importance in these areas in foreseeable
future. This trend has resulted in a fast improvement of
spectroscopic techniques for applications in environmental
science-related fields such as geochemistry and waste man-
agement. Much of our understanding of immobilization
processes of trace elements in complex natural and engi-
neered materials has been obtained by XAS. XAS corre-
sponds to a powerful collection of techniques able to
provide molecular-level characterization
(Teo, 1986; Konigsberger and Prins, 1988; Brown, 1990;
Sto ¨hr, 1992; Saisho and Gohshi, 1996). Most frequently
used XAS techniques are X-ray absorption near edge struc-
ture (XANES) and extended X-ray absorption fine struc-
ture (EXAFS) spectroscopies. While XRD experiments
probe the long-range order of crystalline samples, XAS is
a local probe. The method is well suited for the distinction
of oxidation states and the determination of the coordina-
tion sphere (i.e., type of neighboring atoms, bond length
and coordination numbers) of the X-ray absorber atom
of interest. Dilute samples can be examined (concentration
of X-ray absorber down to a few tens of ppm) and the
experiments can be performed on amorphous solids, sur-
face adsorbed complexes, or species in solution.
In the past years Ca and Al K-edge XAS has been
increasingly utilized to examine the structure of hydrating
calcium aluminates and poorly-crystallized C–S–H phases
(e.g., Richard et al., 1995, 1998; Kirkpatrick et al., 1997;
Lequeux et al., 1999). Investigations of the local coordina-
tion environment of Ca are particularly relevant to the
development of model structures for C–S–H. In addition,
XAS has become an increasingly important analytical tool
A.M. Scheidegger et al. / Waste Management 26 (2006) 699–705
to elucidate immobilization processes in cementitious sys-
tems. For example, XAS has been used to determine the
chemical speciation of trace elements such as Tc, U and
Cr in hydrated cement (Allen et al., 1997; Rinehart et al.,
1997; Zhao et al., 2000; Rose et al., 2003). Several XAS
studies have focused on metal binding mechanisms onto
C–S–H, the quantitatively most important cement mineral
in hydrated cement (Rose et al., 2000, 2001; Pomie `s et al.,
2001; Ziegler et al., 2001; Tommaseo and Kersten, 2002;
Schlegel et al., 2004). The molecular-level information
obtained by XAS indicates that Zn(II) and Pb(II) are
incorporated within the C–S–H matrix and directly linked
at the end of the silicate chains through Pb–O–Si and Zn–
O–Si bonds and do not substitute in the interlayer positions
(Rose et al., 2000, 2001; Tommaseo and Kersten, 2002).
The Eu(III)/C–S–H uptake system behaves differently
and the XAS data indicate that sorbed or coprecipitated
Eu is located at Ca structural sites in a C–S–H-like envi-
ronment (Schlegel et al., 2004).
At the Laboratory for Waste Management at PSI we
have conducted XAS studies to gain information about
the interactions of safety-relevant radionuclides (e.g., Ni,
Sr, Se, U, and I) with hardened cement paste (HCP) and
cement phases. For example, a XAS study provided the
first spectroscopic evidence for the formation of a Ni–Al
LDH phase when HCP was doped with Ni under highly
alkaline conditions (pH = 13.3; Scheidegger et al., 2000).
We also used XAS to gain information about the iodine
redox-state and chemical environment after the reaction
of I?and IO?
et al., 2002). The XAS study showed the absence of any
redox reaction in the uptake system and revealed that the
HCP. Similarly, a XAS study on the immobilization of sel-
cement constituents revealed an ‘‘outer-sphere’’-type bind-
ing of Se(IV) and Se(VI) to HCP as well as to the major
cement constituents (C–S–H, portlandite, AFm, and AFt)
(Bonhoure et al., 2005).
To illustrate the potential of XAS experiments for chem-
ical speciation studies on powdered cementitious materials,
we will briefly outline a XAS study on the immobilization
mechanism of Sn(IV) onto C–S–H and HCP (Bonhoure
et al., 2003). In this study Sn(IV) was considered to be a
representative of the strongly hydrolyzing metal cations
present in the waste matrix. In a cementitious environment
(i.e., pH = 12–14, ?400 mV < Eh< +200 mV; Glasser,
hydrolytic species (Brookins, 1988). Based on XAS data,
evidence is presented demonstrating the formation of a
Sn(IV) inner-sphere surface complex on C–S–H with a
CaO:SiO2 weight ratio of 0.7. The Fourier Transform
(FT) of Sn(IV) doped C–S–H reveals the presence of two
distinct coordination shells at R + DR
R+DR ? 2.8 A˚
XAS data analysis indicates that Sn is surrounded by ?6
3with HCP and cement phases (Bonhoure
3entity is maintained when IO?
3is immobilized by
3Þ and selenate ðSeO2?
4Þ by cement and major
are the dominating
(Fig. 1a; uncorrected for phase shift).
O next-near neighboring atoms at 2.05 A˚. The further dis-
tant coordination shell consists of 1–2 Sn–Si backscatterer
pairs at 3.33 A˚and 1–2 Sn–Ca backscatterer pairs at
3.69 A˚. Based on these structural parameters, a possible
structural model was developed, implying corner sharing
between the Sn octahedra and Si tetrahedra located at
the end of Si chains of C–S–H (Fig. 1b; C–S–H structure
based on 1.1 nm tobermorite; Bonhoure et al., 2003).
In a subsequent study we also conducted XAS investiga-
tions on Sn(IV) doped HCP in order to examine Sn(IV)
binding mechanisms in the complex cement matrix. The
structural parameters deduced from XAS were found to dif-
fer from those determined on the Sn/C–S–H system. At
high Sn(IV) concentrations the XAS data is coincident with
the spectrum of calcium stannate, indicating that Sn(IV)
immobilization in HCP occurred by precipitation of
CaSn(OH)6. At lower Sn(IV) concentrations, however, the
bond length to neighboring atoms of the second coordina-
tion shell was found to be significantly longer than in the
Sn/C–S–H system, suggesting that C–S–H is not the
uptake-controlling phase for Sn(IV) in the cement matrix.
Therefore, an alternative structural model for Sn(IV) bind-
ing in HCP was proposed based on an AFt–type phase act-
ing as the uptake-controlling phase (Bonhoure et al., 2003).
R + R (Å)
Fig. 1. Sn(IV) uptake on C–S–H-0.7: (a) Fourier transforms (modulus
and imaginary parts) of Sn K-edge raw data (—) and data simulated by
FEFF (---); (b) a proposed structural model for Sn binding onto C–S–H-
0.7; modified after (Bonhoure et al., 2003).
A.M. Scheidegger et al. / Waste Management 26 (2006) 699–705
4. X-ray micro probes
Although XAS is the method of choice for defining reac-
tions in complex natural and engineered materials, the
application of XAS becomes problematic when mecha-
nisms operative on the micro-scale have larger conse-
quences. XAS does normally not yield spatially-resolved
structural data since the dimension of the X-ray beam is
much bigger (at most beamlines >100 · 100 lm2) than the
particle size of minerals under investigation (normally
<20 · 20 lm2). Thus, the speciation of a contaminant is
determined indirectly from the averaged XAS signal issued
from all individual species (‘bulk’ XAS measurements). Fit-
ting a combination of XAS spectra from reference com-
pounds with the measured bulk XAS spectrum allows in
principle the identification and the determination of the
concentration of each compound in the sample. The
method is particularly of interest when the minimum num-
ber of relevant (principle) species and the most likely can-
didate phases in a given set of samples is determined by
principle component analysis and target transformation
(e.g., Wassermann et al., 1999; Ressler et al., 2000). Never-
theless, the method can fail because the procedure depends
on the availability of reference standards of the phases
present in the real sample. Bulk XAS in the context of
cement research studies will remain challenging due to
the fact that both XAS investigations of the waste ion of
interest with the complex matrix as well as of individual
cement minerals are needed. Unfortunately, cement miner-
als often have a variable composition and are not well
described (e.g., solid solutions). This may be the reason
why XAS studies on hydrated cement are still sparse in
spite of obvious advantages of the technique.
In view of the importance of small-scale mechanisms
and molecular-level processes in complex heterogeneous
systems, there has been a considerable effort to develop
high resolution analytical synchrotron-based X-ray probes
with which the wealth of structural information provided
by XAS can be obtained on a micro-scale (Rivers et al.,
1988; Vanlangevelde et al., 1990; Devoti et al., 1991; Suzuki
and Uchida, 1992; Janssens et al., 1993; Chevallier et al.,
1996; Hayakawa et al., 1998; Newville et al., 1999; Bohic
et al., 2001; Somogyi et al., 2001; Janousch et al., 2004;
Marcus et al., 2004; Scheidegger et al., 2005). For reviews
on micro-probe beamlines and applications of micro-spec-
troscopy, the reader is referred to Bertsch and Hunter
(2001), Manceau et al. (2002) and Sutton et al. (2002).
Key advantages of synchrotron-based analytical facilities
are the high photon flux, wavelength tunability, and the
polarization of the synchrotron radiation. For example at
the Swiss Light Source (SLS) a new hard X-ray micro-
probe facility is currently being commissioned. The optics
of the micro-XAS beamline is optimized for micro-focus-
ing, with a spatial resolution in the 1 · 1lm2range. The
beam characteristics fulfill all the requirements for opti-
mized micro-XAS measurements, such as spatial stability,
high photon flux and flux density, high energy tunability
(?4 to ?20 keV), high energy resolution (DE/E < 10?4),
and minimized contamination by high energy radiation
(harmonics). As a unique feature, micro-spectroscopic
experiments can also be conducted with active samples
(Scheidegger et al., 2005).
Thus far most micro-XRF/XAS studies conducted with
complex and inherently heterogeneous materials have been
performed in the hard X-ray regime (above ?4 keV).
Micro-spectroscopy studies in the soft X-ray region are
more challenging since a different instrumental set-up is
required and the experiments must be performed under
vacuum. The new LUCIA beamline at SLS is a unique
beamline dedicated to microXAS/XRF studies within the
energy regime from 1 to 7 keV (Janousch et al., 2004). With
this energy range, the chemical speciation of elements such
as S (K-edge: 2.4 keV), P (K-edge: 2.1 keV), Mg (K-edge:
1.3 keV), Ca (K-edge: 4.0 keV), Si (K-edge: 1.8 keV) Al
(K-edge: 1.6 keV) and Na (K-edge: 1.1 keV) can be probed.
Since the above elements are essential for determining the
reactivity of cement, it can be anticipated that the use of
micro-XRF/XAS in the soft X-ray region will add a new
dimension to chemical speciation and understanding chem-
ical reactivities in cementitious materials.
In many scientific disciplines spatially-resolved molecu-
lar-level information is the key to understand the funda-
mental physiochemistry of processes. In most cases, the
information sought can be obtained by the synergistic use
of micro-X-ray fluorescence (micro-XRF), micro-XAS,
and micro-XRD. Micro-XRF is essential in a first stage
to map the partitioning of trace contaminants among coex-
isting mineral phases in the investigated sample. Micro-
XAS opens up the possibility to identify individually the
different mechanisms of metal uptake on a molecular-level.
Finally, micro-XRD allows X-ray diffraction determina-
tion to be performed on small particles and is thus suited
for micron size phase identifications required to determine
which mineral species the trace element is bound/associated
to. However, one must keep in mind that the quality of
XRD is degraded as crystallite size decreases. Therefore
the success of micro-XRD experiments declines as grain
size decreases to sub micron dimensions. Electron diffrac-
tion often usefully complements XRD for very small
In the following we will present a case study of an ongo-
ing work addressing the influence of the inherent spatial
heterogeneity of solidified cementitious waste on the speci-
ation of Co. Cement minerals are typically present as dis-
crete particles in the size range of a few nanometers to a
few hundred micrometers. It is this very feature that may
control the overall chemical reactivity of cement and makes
cementitious systems so difficult to understand.
5. Micro-spectroscopic investigations on Co immobilization
Micro-XRF and micro-XAS were used to investigate Co
uptake by HCP. The samples were prepared from a com-
A.M. Scheidegger et al. / Waste Management 26 (2006) 699–705
mercial calcite-containing sulfate-resisting Portland cement
(CEM I 52.5 N HTS) by mixing Co(II) nitrate salt solu-
tions to unhydrated cement at a water-to-cement ratio
(w/c) of 0.4 (final Co concentration in the cement matrix:
5000 ppm hydration time of 3 days) (see also Lothenbach
and Wieland, 2005). The micro-spectroscopic investiga-
tions on polished thin sections were conducted at beamline
10.3.2 (Advanced Light Source, Berkeley, USA) using a
beam size of 5 · 5 lm2(Marcus et al., 2004).
The micro-XRF maps show that Co is heterogeneously
distributed in the cement matrix (Fig. 2a and b). Typically
Co-rich spots up to ?50 lm2in size (e.g., spot 1) as well as
characteristic Co-rich ring-like structures with diameters
up to ?200 lm (e.g., spot 2) were observed. Fig. 2c shows
the normalized, background-subtracted and k3-weighted
micro-XAS spectra of spot 1 and 2 together with Co refer-
ence compounds. The spectrum of spot 2 was collected on
the ring-like structure and shows a change in frequency and
a clear shift of the first oscillation compared to spot 1. By
comparing the micro-XAS data with Co reference spectra
it becomes evident that the spectrum of spot 1 exhibits sim-
ilarities with the spectra of Co(II) references, whereas the
spectrum of spot 2 shows similarities with the spectra of
Co(III) compounds. Data analysis finally revealed that
Co–O and Co–Co bond distances for spot 1 (RCo–O=
2.06 A˚; RCo–Co= 3.13) are in the same range as Co–O
and Co–Co distances in Co(II) compounds such as
Co(II)-hydroxide-like phases (Co(OH)2: RCo–O= 2.09 A˚,
RCo–Co= 3.17 A˚; Co–Al LDH: RCo–O= 2.08 A˚, RCo–Co=
3.09 A˚) or Co-phyllosilicates
Co3Si4O10(OH)2, RCo–O= 2.09 A˚, RCo–Co= 3.13 A˚; Man-
ceau et al., 1999). Shorter Co–O and Co–Co distances
are observed for spot 2 (RCo–O= 1.90 A˚, RCo–Co=
2.80 A˚), suggesting that Co is present as Co(III) that is
incorporated into a Co(III)O(OH)-like phase (RCo–O=
RCo–Co= 2.85 A˚)
(Co-asbolane (Co, Ni)1?y(MnO2)2?x(OH)2?y?2xÆ nH2O
1.89 A˚, RCo–Co= 2.80 A˚; Manceau et al., 1987, 1997).
The micro-spectroscopic findings demonstrate the pres-
ence of a Co(II) hydroxide-like phase at some spots in the
Co-doped cement sample. At other spots of interest,
however, Co was found to be oxidized to Co(III) and
Co-phyllomanganate. The micro-XRF experiments sug-
gest that the Co(III) phase seems to form ring-like struc-
tures. The oxidation of Co(II) to Co(III) is attributed to
the presence of oxidizing agents such as traces of O2,
Mn(IV) or Fe(III) species. A surprising result of the
micro-spectroscopic study is that oxidation of Co(II) is
a locally occurring process. This finding demonstrates that
the inherent heterogeneity of cement may well control the
overall chemical reactivity of Co in cement. Future works
will focus on the identification of the oxidizing agent
responsible for Co(II)/Co(III) redox processes occurring
Fig. 2. Elemental Co distribution map of a Co-doped cement sample hydrated for 3 days: (a) Co-rich spot 1; (b) Co-rich spot 2; (c) k3-weighted,
normalized, background-subtracted Co K-edge XAS spectra collected at spot 1 and 2 in comparison with the spectra of Co reference compounds
(Co-phyllosilicate: Manceau et al. (1999); Co-asbolane: Manceau et al. (1987); Co-buserite: Manceau et al. (1997), other references: this study).
A.M. Scheidegger et al. / Waste Management 26 (2006) 699–705
in hydrating cement. Further, a multi-technique approach
is presently developed, which will allow complementary
investigations using micro-XRF/XAS and BSE imaging
of the same sample area. With the novel approach, infor-
mation on the local chemical speciation gained by micr-
constituents identified by BSE, based on grey values and
micro-XAS offer a great potential for investigating com-
plex and highly heterogeneous samples such as cement
in a non-destructive fashion. While micro-XRF can yield
spatially-resolved information on the trace element distri-
bution, micro-XRD allows micron size phase identifica-
molecular-level information on the spatial variability of
chemical speciation. Given the characteristic length-scale
of the phenomena of interest (e.g., size range of discrete
cementitious particles, spatial extent of corrosion layers),
achieving micrometer resolution is important. While alter-
native micro-probe techniques could also provide elemen-
tal distributions, the spatially resolved determination of
chemical speciation is restricted to micro-XAS techniques.
Molecular-level speciation, however, is often the key to
The authors like to thank Dr. A. Manceau for kindly
providing some cobalt reference spectra used in this study.
Experimental assistance of the staff of the Swiss-Norwegian
Beamline (SNBL) and the Dutch-Belgium Beamline (DUB-
BLE) at the European Synchrotron Radiation Facility
(ESRF) (Grenoble, France) is gratefully acknowledged.
Thanks are extended to Matthew Marcus (Beamline
10.3.2, ALS, Berkeley, USA) for his support during the
Light Source is supported by the Director, Office of Sci-
ence, Office of Basic Energy Sciences, Materials Science
Division, of the US Department of Energy under Contract
No. DE-AC03-76SF00098 at Lawrence Berkeley National
Agency, I.A.E., 1999. Near Surface Disposal of Radioactive Waste.
Allen, P.G., Siemering, G.S., Shuh, D.K., Bucher, J.J., Edelstein, N.M.,
Langton, C.A., 1997. Technetium speciation in cement waste forms
determined by X-ray absorption fine structure spectroscopy. Radio-
chim. Acta 76, 77–86.
Atkins, M., Glasser, F.P., Moroni, L.P., Jack, J.J., 1994. Thermodynamic
Modelling of Blended Cements at Elevated Temperatures (50 ?C to
90 ?C). DoE/UMIP/PR/94.011.
Bertsch, P., Hunter, D.B., 2001. Applications of synchrotron-based X-ray
microprobes. Chem. Rev. 101, 1809–1842.
Bohic, S., Simionovici, A., Snigirev, A., Ortega, R., Deves, G.,
Heymann, D., Schroer, C.G., 2001. Synchrotron hard X-ray micro-
probe: fluorescence imaging of single cells. Appl. Phys. Lett. 78,
Bonhoure, I., Scheidegger, A.M., Wieland, E., Da ¨hn, R., 2002. Iodine
species uptake by cement and C–S–H studied by K-edge X-ray
absorption spectroscopy. Radiochim. Acta 90, 647–651.
Bonhoure, I., Wieland, E., Scheidegger, A.M., Ochs, M., Kunz, D.,
2003. EXAFS study of Sn (IV) immobilization by hardened cement
paste and calcium silicate hydrates. Environ. Sci. Technol. 37, 2184–
Bonhoure, I., Baur, I., Wieland, E., Johnson, C.A., Scheidegger, A.M.,
2005. Uptake of Se(IV/VI) oxyanions by hardened cement paste and
cement minerals: An X-ray absorption spectroscopy study. Cem.
Concr. Res. 36, 91–98.
Brookins, D.G., 1988. Eh-pH Diagrams for Geochemistry. Springer
Brown, G.E., 1990. Spectroscopic studies of chemisorption reaction
mechanisms at oxide-water interfaces. In: Hochella, M.F., White, A.F.
(Eds.), Mineral–Water Interface Geochemistry, Washington, DC, pp.
Brunet, F., Bertani, P., Charpentier, T., Nonat, A., Virlet, J., 2004.
Application of Si-29 homonuclear and H-1–Si-29 heteronuclear NMR
correlation to structural studies of calcium silicate hydrates. J. Phys.
Chem. B 108, 15494–15502.
Chevallier, P., Dhez, P., Legrand, F., Erko, A., Agafonov, Y., Panchenko,
L.A., Yakshin, A., 1996. The LURE-IMT X-ray fluorescence photon
microprobe. J. Trace Microprobe Tech. 14, 517–539.
Cocke, D.L., Mollah, M.Y.A., 1993. The chemistry and leaching
mechanisms of hazardous substances in cementitious solidification/
stabilization systems. In: Spence, R.D. (Ed.), Chemistry and Micro-
structure of Solidified Waste Forms. Lewis Publishers, Boca Rato.
Colombet, P., Grimmer, A.R., Zanni, H., Sozanni, P., 1998. Nuclear
Magnetic Resonance Spectroscopy of Cement-Based Materials.
Devoti, R., Zontone, F., Tuniz, C., Zanini, F., 1991. A synchrotron
radiation microprobe for X-ray-fluorescence and microtomography at
Elettra – focusing with bent crystals. Nucl. Instrum. Meth. Phys. Res.
Sect. B-Beam Interact. Mater. Atoms 54, 424–428.
Famy, C., Scrivener, K.L., Atkinson, A., Brough, A.R., 2002. Effects of an
early or a late heat treatment on the microstructure and composition of
inner C–S–H products of Portland cement mortars. Cem. Concr. Res.
Glasser, F.P., 1993. Chemistry of cement-solidified waste forms. In:
Spence, R.D. (Ed.), Chemistry and Microstructure of Solidified Waste
Forms. Lewis Publishers, Boca Raton, pp. 1–39.
Hayakawa, S., Goto, S., Shoji, T., Yamada, E., Gohshi, Y., 1998. X-ray
microprobe system for XRF analysis and spectroscopy at SPring-8
BL39XU. J. Synchr. Rad. 5, 1114–1116.
Izumi, F., 1993. Rietveld Analysis Programs RIETAN and PREMOS and
Special Applications. Oxford University Press, Oxford.
Janousch, M., Flank, A.-M., Lagarde, P., Cauchon, G., Bac, S.,
Dubuisson, J.M., Schmidt, T., Wetter, R., Grolimund, D., Scheideg-
ger, A.M., 2004. LUCIA – a new 1–7 keV l-XAS beamline. AIP Conf.
Proc. (USA) 705, 312–315.
Janssens, K., Vincze, L., Adams, F., Jones, K.W., 1993. Synchrotron-
radiation-induced X-ray-microanalysis. Anal. Chim. Acta 283, 98–110.
Kirkpatrick, R.J., Brown, G.E., Xu, N., Cong, X., 1997. X-ray absorption
spectroscopy of C–S–H and some model compounds. Adv. Cement
Res. 9, 31–36.
Konigsberger, D.C., Prins, R., 1988. X-ray Absorption: Principles,
Applications, Techniques of EXAFS, SEXAFS and XANES. Wiley,
Lequeux, N., Morau, A., Philippot, S., Bloch, P., 1999. Extended X-ray
absorption fine structure investigation of calcium silicate hydrates. J.
Am. Ceram. Soc. 82, 1299–1306.
Levi, J., Izabel, C., Kalunzy, Y., 1990. Safety Assessment of Radioactive
Repositories. OECD, Paris.
A.M. Scheidegger et al. / Waste Management 26 (2006) 699–705
Lothenbach, B., Wieland, E., 2005. A thermodynamic approach to the
hydration of sulphate-resisting Portland cement. Waste Manage, in
Manceau, A., Llorca, S., Calas, G., 1987. Crystal chemistry of cobalt and
nickel in lithiophorite and asbolane from New Caledonia. Geochim.
Cosmochim. Acta 51, 105–113.
Manceau, A., Drits, V., Silvester, E., Bartoli, C., Lanson, B., 1997.
Structural mechanism of Co2+oxidation by the phyllomanganate
buserite. Am. Miner. 82, 1150–1175.
Manceau, A., Schlegel, M., Nagy, K.L., Charlet, L., 1999. Evidence for
the formation of trioctahedral clay upon sorption of Co2+on quartz. J.
Colloid Interf. Sci. 220, 181–197.
Manceau, A., Marcus, M.A., Tamura, N., 2002. Applications of
synchrotron radiation in low-temperature geochemistry and environ-
mental science. In: Fenter, P., Sturchio, N.C. (Eds.), Mineralogical
Society of America, Washington, DC, pp. 341–428.
Mansoutre, S., Lequex, N., 1996. Quantitative phase analysis of Portland
cements from reactive powder concretes by X-ray powder diffraction.
Adv. Cem. Res. 8, 175–182.
Marcus, M., MacDowell, A.A., Celestre, R., Manceau, A., Miller, T.,
Padmore, H.A., Sublett, R.E., 2004. Beamline 10.3.2 at ALS: a hard
X-ray microprobe for environmental and material sciences. J. Synchr.
Rad. 11, 239–247.
Newville, M., Sutton, S., Rivers, M., Eng, P., 1999. Micro-beam X-ray
absorption and fluorescence spectroscopies at GSECARS: APS
beamline 131D. J. Synchr. Rad. 6, 353–355.
Plo ¨tze, M., 2000. Quantitative Phase Analysis of Portland Cement Clinker
With the Rietveld Method. Balkeme, Rotterdam.
Pomie `s, M.P., Lequex, N., Boch, P., 2001. Speciation of cadmium in
cement Part I. Cd2+uptake by C–S–H. Cem. Concr. Res. 31, 563–
Ressler, T., Wong, J., Roos, J., Smith, I.L., 2000. Quantitative speciation
of Mn-bearing particles emitted from autos burning (methylcyclopen-
tadienyl) manganese tricarbonyl-added gasolines using XANES spec-
troscopy. Environ. Sci. Technol. 34, 950–958.
Rinehart, T.L., Schulze, D.G., Briccka, R.M., Bajt, S., Blatchley, E.R.,
1997. Chromium leaching vs. oxidation state for a contaminated
solidified/stabilized soil. J. Hazard. Mater. 52, 213–221.
Richard, N., Lequeux, N., Boch, P., 1995. An X-ray absorption study of
phases formed in high-alumina cements. Adv. Cem. Res. 7, 159–169.
Richard, N., Lequeux, N., Florian, P., 1998. Changes in the structure of
CaAl2O14H20during heat treatments: an X-ray absorption spectros-
copy and27Al NMR studies. In: Colombet, P., Grimmer, A.R., Zanni,
H., Sozanni, P. (Eds.), Nuclear Magnetic Resonance Spectroscopy of
Cement-Based Materials. Springer-Verlag, Berlin.
Rivers, M.L., Sutton, S.R., Smith, J.V., 1988. A synchrotron X-ray-
fluorescence microprobe. Chem. Geol. 70, 179.
Rose, J., Moulin, I., Hazemann, J.L., Masion, A., Bertsch, P.M., Bottero,
J.Y., Mosnier, F., Haehnel, C., 2000. X-ray absorption spectroscopy
study of immobilization processes for heavy metals in calcium silicate
hydrates: 1. Case of lead. Langmuir 16, 9900–9906.
Rose, J., Moulin, I., Masion, A., Bertsch, P.M., Wiesner, M.R., Bottero,
J.Y., Mosnier, F., Haehnel, C., 2001. X-ray absorption spectroscopy
study of immobilization processes for heavy metals in calcium silicate
hydrates: 2. Zinc. Langmuir 17, 3658–3665.
Rose, J., Be ´nard, S.J., Borschneck, D., Hazemann, J.-L., Vichot, A.,
Lemarchand, D., Bottero, J.-Y., 2003. First insights of Cr speciation in
leached Portland cement using X-ray spectromicroscopy. Environ. Sci.
Technol. 37, 4864–4870.
Saisho, H., Gohshi, Y., 1996. Applications of Synchrotron Radiation to
Materials Analysis. Elsevier Health Science.
Scheidegger, A.M., Wieland, E., Scheinost, A.C., Da ¨hn, R., Spieler, P.,
2000. Spectroscopic evidence for the formation of layered Ni–Al
double hydroxides in cement. Environ. Sci. Technol. 34, 4545–4548.
Scheidegger, A.M., Grolimund, D., Harfouche, M., Willimann, M.,
Meyer, B., Da ¨hn, R., Gavillet, D., Nicolet, M., Heimgartner, P., 2005.
The Micro-XAS Beamline at the Swiss Light source (SLS): A New
Analytical Facility Suited for X-ray Micro-Beam Investigations with
Radioactive Samples. NEA Publication, in press.
Schlegel, M.L., Pointeau, I., Coreau, N., Reiller, P., 2004. Mechanism of
europium retention by calcium silicate hydrates: an EXAFS study.
Environ. Sci. Technol. 38, 4423–4431.
Somogyi, A., Drakopoulos, M., Vincze, L., Vekemans, B., Camerani, C.,
Janssens, K., Snigirev, A., Adams, F., 2001. ID18F: a new micro-X-
ray fluorescence end-station at the European Synchrotron Radiation
Facility (ESRF): preliminary results. X-Ray Spectrom. 30, 242–252.
Spence, R.D., 1993. Chemistry and Microstructure of Solidified Waste
Forms. Lewis, Boca Raton.
Scrivener, K.L., Fu ¨llmann, T., Gallucci, E., Walenta, G., Bermejo, E.,
2004. Quantitative study of Portland cement hydration by X-ray
diffraction/Rietveld analysis and independent methods. Cem. Concr.
Res. 34, 1541–1547.
Sto ¨hr, J., 1992. NEXAFS Spectroscopy. Springer-Verlag, Berlin.
Struble, L.J., 1991. Quantitative phase analysis of clinker using X-ray
diffraction. CCAGDP 13, 97–102.
Sutton, S.R., Bertsch, P.M., Newville, M., Rivers, M., Lanzirotti, A., Eng,
P., 2002. Microfluorescence and microtomography analyses of heter-
ogeneous earth and environmental materials. In: Applications of
Synchrotron Radiation in Low-Temperature Geochemistry and Envi-
ronmental Sciences. American Mineralogical Society, pp. 429–483.
Suzuki, Y., Uchida, F., 1992. Hard X-ray microprobe with total-reflection
mirrors. Rev. Scientific Instru. 63, 578–581.
Taylor, H.F.W., 1997. Cement Chemistry. Thomas Telford Publishing,
Teo, B.K., 1986. EXAFS: Basic Principles and Data Analysis. Springer
Tommaseo, C.E., Kersten, M., 2002. Aqueous solubility diagrams for
cementitious waste stabilization systems. 3. Mechanism of zinc
immobilization by calcium silicate hydrate. Environ. Sci. Technol.
Vanlangevelde, F., Tros, G.H.J., Bowen, D.K., Vis, R.D., 1990. The
synchrotron radiation microprobe at the SRS, Daresbury (UK) and is
applications. Nucl. Instrum. Meth. Phys. Res. Sect. B-Beam Interact.
Mater. Atoms 49, 544–550.
Wassermann, S.R., Allen, P.G., Shuh, D.K., Bucher, J.J., Edelstein, N.M.,
1999. EXAFS and principal component analysis: a new shell game. J.
Synchr. Rad. 6, 284–286.
Zhao, P., Allen, P.G., Sylvester, E.R., Viani, B.E., 2000. The partitioning
of uranium and neptunium onto hydrothermally altered concrete.
Radiochim. Acta 88, 729–736.
Ziegler, F., Scheidegger, A.M., Johnson, C.A., Da ¨hn, R., Wieland, E.,
2001. The sorption mechanisms of zinc to calcium silicate hydrate: an
X-ray absorption fine structure (XAFS) investigation. Environ. Sci.
Technol. 35, 1550–1555.
A.M. Scheidegger et al. / Waste Management 26 (2006) 699–705