In-situ early age hydration of cement-based materials by synchrotron X-ray powder diffraction

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 noncrystalline 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: mar[email protected] 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 AFt AFm CSH2 Stratl. AFt C4A3S b-C2S C4AF AFm AFt 1h 10h 5h 12h 26h 34h I (a.u) º/2q CSH2 CSH2 Stratl. AFt AFt Stratl. Stratl. 2 4 6 8 10 12 14 I (a.u) º/2q 1h 10h 5h 11h 24h 51h AFt CSH2 AFt C4A3S a-C2S C4AF AFt CSH2 CSH2 AFt AFt 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 C4A3S AFt AFt AFt a´-C2S AFt a´-C2S C2AS a´-C2S C4AF AFt AFt I (a.u) a´-C2S 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 AFt AFt AFt b-C2S b-C2S AFt Stratl. AFt Stratl. AFt AFt C4AF Stratl. AFt I (a.u) b-C2S G10B0_ 26h C10B0_26h #0 ALBA Hist 1 Lambda 0.6198 A, L-S cycle 1327 Obsd. and Diff. Profiles 2-Theta, deg Counts 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 X10E 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 Counts 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 X10E 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 Counts 3.2 3.4 3.6 3.8 4.0 4.2 4.4 4.6 X10E 3 1.0 1.5 2.0 2.5 3.0 AFt AFt AFm 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. 110 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 110 0 5 10 15 20 25 30 35 40 Ettringite Ye'elimite Gypsum wt (%) t(h) REFERENCES 0.7 mm Diameter of capillaries