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

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