Post on 28-Jul-2022
1 Departamento de Química Inorgánica, Cristalografía y Mineralogía, Universidad de Málaga, 29071 Málaga 2 Servicios Centrales de Investigación, Universidad de Málaga, 29071 Málaga
3 CELLS-ALBA synchrotron radiation facility, Ctra. BP1413 km 3.3, 08290 Cerdanyola del Vallès, Barcelona 4Henkel Adhesive Technologies
#XDS. X-ray Data Services http://www.xdataser.com/
In-situ early age hydration of cement-based materials by synchrotron X-ray powder diffraction
M. García-Maté1,#, G. Álvarez-Pinazo1,#, L. León-Reina2, A.G. De la Torre1,#, I. Santacruz1, M.A.G. Aranda1,3, #, K. W. Chou3,4, U. Neuhausen4, S. Petrash4
ABSTRACT Cement based binders are building materials of worldwide importance. Since these samples are very complex, the knowledge and control of their mineralogical composition are essential to design and predict materials with specific/improved performance [1]. Rietveld quantitative phase analysis (RQPA) allows the quantification of crystalline phases and, when combined with specific methodologies, as the addition of an internal standard or the external standard approach (G-factor), amorphous and non-crystalline phases can also be quantified. However, to carry out a proper RQPA in hydrated cementitious materials, a good powder diffraction pattern is necessary. In this work, synchrotron X-ray powder diffraction (SXRPD) has been used, allowing in-situ measurements during the early-age hydration process. This work deals with the early hydration study of cement-based materials. The studied samples were: a laboratory-prepared belite calcium sulfoaluminate (BCSAF) clinker (non-active) [2] mixed with 10 wt% gypsum, labelled G10B0; two active laboratory-prepared BCSAF clinkers (activated with 2 wt% borax) [2], one mixed with 10 wt% of gypsum and the other one with 10 wt% of monoclinic bassanite, hereafter named G10B2 and B10B2, respectively; and an environmentally-friendly binder sample from Henkel, composed of calcium sulphate hemihydrate mixed with 15 wt% Portland cement (OPC) and 10 wt% Metakaolin, hereafter named H1. Cement nomenclature will be used hereafter, i. e. C=CaO, S=SiO2, A=Al2O3, F=Fe2O3 and S=SO3.
Acknowledgments: We thank the financial support by MAT2010-16213 and P11-FQM-7517.
E-mail: martagmate@uma.es
Non-active clinker BCSAF_B0
b-C2S 50 wt%, C4A3S
30 wt%, C4AF 20 wt%
Active clinker BCSAF_B2
a’H-C2S 50 wt%, C4A3S 30 wt%, C4AF 20 wt% addition of Na2B4O7·10H2O 2.0 wt% B2O3
l = 0.62 Ǻ
Debye Scherrer configuration
Capillaries were spun
Angular range 1-35o (in 2q)
15 minutes per pattern
w/c = 0.55
Cement Water
Sealed with wax
0.5 mm
MYTHEN
Detector
Henkel binder_H1
Bassanite 75 wt%, Alite 15 wt%,
Metakaolin 10 wt%
Clinker B0/B2
+ 10 wt% of Gypsum
or Bassanite Cement
10 wt% of gypsum
G10B0 & G10B2
10 wt% of bassanite
B10B2
SAMPLE PREPARATION
G10B0, G10B2 and B10B2
H1
w/c = 0.375
+ 15 wt% of Quartz (internal standard)
2 4 6 8 10 12 14
AF
t
AF
m
CS
H2
Str
atl.
AF
t
C4A
3S
b-C
2S
C4A
F
AF
m
AF
t
1h
10h
5h
12h
26h
34h
I (a
.u)
º/2q
CS
H2
CS
H2
Str
atl.
AF
t
AF
t
Str
atl. Str
atl.
2 4 6 8 10 12 14
I (a
.u)
º/2q
1h
10h
5h
11h
24h
51h
AF
t
CS
H2
AF
t
C4A
3S
a-C
2S
C4A
F
AF
t
CS
H2
CS
H2
AF
tA
Ft
G10B0 G10B2
1st Important difference in the hydration process:
Degree of reaction after 1 hour: G10B0 (a~25%); G10B2 (a~10%)
Gypsum is completely dissolved: G10B0= 5 hours; G10B2= 11 hours
Ye'elimite is completely dissolved: G10B0= 26 hours; G10B2= 51 hours (remains)
AFt crystallization after 1 hour: G10B0= 14.2(2) wt% (a~30%); G10B2= 1.9(1) wt% (a~5%)
2st Important difference in the hydration process:
b-C2S and C4AF starts to be dissolved in
G10B0 after 1 day crystallization of AFm
type phases [2], including stratlingite.
On the other hand, for G10B2, a'H-C2S
percentage remains constant up to 51 hours
of hydration and C4AF dissolves very slowly
after 14 h.
b-C2S reacts faster than a'H-C2S
Hydration behavior of belite is more
dependent on the chemical environment
(higher AH3 content) than on its
polymorphism. Furthermore, slower
hydration G10B2 led to much higher
mechanical strength developments.
C10B2 ALBA 24h Hist 1
Lambda 0.6198 A, L-S cycle 1455 Obsd. and Diff. Profiles
2-Theta, deg
4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0
AFt
AFt
C4AF
AFt
AFt
AFt
AFt
AFt
C4A
3S
AFt AFt
AFt
a´-C
2S
AFt
a´-C
2S
C2AS
a´-C
2S
C4AF AFt
AFt
I (a
.u)
a´-C
2S
G10B2_ 24h
C10B0_26h #0 ALBA Hist 1
Lambda 0.6198 A, L-S cycle 1327 Obsd. and Diff. Profiles
2-Theta, deg
4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0
C10B0_26h #0 ALBA Hist 1
Lambda 0.6198 A, L-S cycle 1327 Obsd. and Diff. Profiles
2-Theta, deg
4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0
AFt
AFt A
Ft
AFt AFt
b-C
2S
b-C
2S
AFt
Str
atl.
AFt
Str
atl.
AFt
AFt
C4AF Str
atl.
AFt
I (a
.u)
b-C
2S
G10B0_ 26h
C10B0_26h #0 ALBA Hist 1
Lambda 0.6198 A, L-S cycle 1327 Obsd. and Diff. Profiles
2-Theta, deg
Cou
nts
3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6
X10
E 3
1.0
1.
5
2.0
2.
5
3.0
C10B0_26h #0 ALBA Hist 1
Lambda 0.6198 A, L-S cycle 1327 Obsd. and Diff. Profiles
2-Theta, deg
Cou
nts
3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6
X10
E 3
1.0
1.
5
2.0
2.
5
3.0
C10B0_26h #0 ALBA Hist 1
Lambda 0.6198 A, L-S cycle 1327 Obsd. and Diff. Profiles
2-Theta, deg
Cou
nts
3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6
X10
E 3
1.0
1.
5
2.0
2.
5
3.0
AFt
AFt
A
Fm
d=1.07Ǻ
AFm
-10
AFm
-12
AFm
-14
AFt
C4AF
RESULT RESULTS & DISCUSSION The role of calcium sulfate source
[1] H. F. W. Taylor, Cement Chemistry. Telford, London, (1997). [2] G. Álvarez-Pinazo, A. Cuesta, M. García-Maté, I. Santacruz, E.R. Losilla, A.G. De la Torre, L. León-Reina, M.A.G. Aranda, Cem. Concr. Res. 42 (2012) 960.
CONCLUSIONS
The type of sulphate source has important
consequences on the hydration of the active
BCSAF cement pastes. Bassanite is quickly
dissolved and it precipitates as gypsum within the
first hour of hydration (in B10B2). At that time,
ettringite starts to crystallize (Figure 1), and after
12 hours is almost fully crystallized, similar to
G10B2.
PB_anh_Q
90m_PB_H_Q
32h40m_PB_H_Q
Anhydrous
1.5 h
32.6 h
Henkel binder H1
In H1, bassanite transforms into gypsum
within the first hour, being the principal
hydration product; ettringite starts to be
formed just after few minutes of hydration
(Figure 2).
Figure 1. Direct Rietveld quantitative phase analysis results (wt%) for G10B2 (top) and B10B2 (bottom) sample as a function of hydration time.
Figure 2. Rietveld plots for anhydrous (top), hydrated after 1.5
hours (middle) and 32.7 hours (bottom) H1 cement. Bassanite,
gypsum and ettringite marked with triangle, circle and square,
respectively.
1 10
0
5
10
15
20
25
30
35
40
Ettringite
Ye'elimite
Bassanite
Gypsum
wt
(%)
t(h)
G10B2
B10B2
Experimental setup & data analysis procedures are mature and they can be applied to several chemical reactions including hydration of cements.
In-situ early-age hydration study of cement-based materials have been analyzed with synchrotron XRPD (SXRPD) and Rietveld methodology.
Ye'elimite, in the B10B0 pastes, dissolves at a higher pace than in the active one (degree of reaction is α~25% and α~10% at 1 h, respectively)
In B10B0, the presence of high amounts of ettringite at early hours of hydration implies a concomitant large amount of available aluminates,
which can precipitate as stratlingite, C2ASH8, enhancing belite reactivity.
The very fast dissolution of bassanite has been quantified showing the accuracy of the reported methodology.
These results are crucial in the understanding and development of improved cement materials.
Influence of activation in the hydration behavior at early ages
DATA COLLECTION HYDRATION PROCEDURE
RAW MATERIALS
1 10
0
5
10
15
20
25
30
35
40
Ettringite
Ye'elimite
Gypsum
wt
(%)
t(h)
REFERENCES
0.7 mm
Diameter of capillaries
brought to you by COREView metadata, citation and similar papers at core.ac.uk
provided by Repositorio Institucional Universidad de Málaga