Quantification of mineral admixtures on cement by Rietveld method. Luciano Gobbo, PhD, Geosciences Intitute - USP

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2 Quantification of mineral admixtures on cement by Rietveld method Luciano Gobbo, PhD, Geosciences Intitute - USP Luciano.gobbo@panalytical.com

3 X ray Diffraction Bragg s law: n =2dsin

4 Intensity (counts) Difractogram 100 % intensity Angular positions Relative intensities Theta ( )

5 Crystalline Amorphous

6 Why XRD? 1. Mechanical properties and performance characteristics of clinkers and cements are primarily determined by: structure, composition, and distribution of crystalline (mineral) phases Alite Belite C 3 A C 4 AF CaO MgO....not elemental concentration.

7 Why XRD? Cement compound Formula Cement property Alita C 3 S Strengh (initial) Belita C 2 S Strengh (28 days) Aluminate C 3 A Setting time Ferrite C 4 AF Sulphate attack / not in white cement Mayenite C 12 A 7 Faster setting time Arcanite K 2 SO 4 Initial strengh + fast setting time, lower final strengh Langbeinite K 2 SO 4.2CaSO 4 Initial strengh + fast setting time, lower final strengh Free lime CaO Expansive hydration [CaO + H 2 O Ca(OH) 2 ] Periclase MgO Expansive hydration [MgO + H 2 O Mg(OH) 2 ] Calcite / Dolomite (Mg,Ca)CO 3 Carbonatation Gypsum CaSO 4.2H 2 O Setting retarder Bassanite CaSO 4.1/2H 2 O False setting Anhydrite CaSO 4 Slow setting

8 Clinker quantification Bogue Method Microscopy XRD - Rietveld

9 Bogue Developed in Elements (adapted later) Alite 3-4% substituent's - Na +, K +, Mg 2+, Fe 3+ (Ca 2+ ) - Al 3+, P 5+, S 6+ (Si 4+ ) Belite 6% substituent's K +, Na +, Mg 2+ (Ca 2+ ) - Fe 3+, Al 3+, P 5+, S 6+ (Si 4+ ) Ferrite 10% substituent's Mg 2+, Si 4+

10 Microscopy

11 Microscopy

12 XRD Fast Reproducible Possible to quantify Types of Alite, Belite Cubic and Orthorhombic C 3 A Alkaline sulphates Periclase, Free lime, Ca(OH) 2

13 % MPa compressive strength [N/mm²] XRD real case C 3 S C 2 S C 3 A C AF Time [days] C3S Bogue C3S Rietveld N Zeitachse 59

14 XRD real case

15 XRD Rietveld Method Rietveld (1969) developed a means to refine crystal structure information for powder (neutron) diffraction data by: Using initial crystal structures and Minimizing the differences between calculated and measured profiles using a least squares approach with many variables for each phase.

16 XRD Rietveld Method The Rietveld method uses all peaks and the complete profile for the analysis: 1. For each phase present a diffraction pattern is calculated 2. For all phases a total pattern is generated 3. The difference between observed and calculated patterns is minimized by varying parameters in the model through a least squares process The Rietveld method is the best practical way to quantify the phases in clinker/cement Quantitative analysis of clinker and cement: Rietveld

17 XRD Rietveld Method 1 st Step Data collection 2 nd Step Calculated pattern insertion 3 rd Step Start Refinement of each parameter (scale factor, zero shift, unit cell, profile (Gauss/Lorenz), assimetry, prefered orientation...)

18 XRD Rietveld Method 1 st Step Data Collection 2 nd Step Calculated diffractogram insertion 3 rd Step Start Refinement of each parameter (scale factor, zero shift, unit cell, profile (Gauss/Lorenz), assimetry, prefered orientation...)

19 XRD Rietveld Method Phase A Calculated area + corrections = phase amount Phase A = 64% Phase B = 36% Phase B Phase A Phase B

20 XRD Rietveld Method A

21 XRD Rietveld Method B

22 XRD Rietveld Method C

23 XRD Rietveld Method D

24 XRD Rietveld Method E

25 XRD Rietveld Method F

26 XRD Rietveld Method

27 XRD Rietveld Method Final Result

28 Metodology - Cements prepared in laboratory with known amounts of gypsum, slag and fly ash - Data collection using an Empyrean diffractometer (Panalytical) in 5 minutes/sample - Rietveld quantitative analysis with High Score Software from Panalytical

29 Results

30 Fly ash Fly ash Bottom Ash

31 Slag Amostra n Básica/Ácida % em massa de vidro (m) CaO/SiO 2 IH* Alemanha IH** Brasil S1 >1,64 Básica 87,3 1,17 1,27 1,84 S2 >1,64 Básica 88,7 1,16 1,27 1,82 S3 >1,64 Básica 89,0 1,19 1,28 1,85 S4 >1,64 Básica 90,1 1,15 1,26 1,82 S5 >1,64 Básica 90,2 1,14 1,25 1,81 S6 >1,64 Básica 90,8 1,10 1,22 1,77 S7 >1,64 Básica 93,9 1,21 1,25 1,78 S8 >1,64 Básica 99,2 1,22 1,26 1,77 S9 >1,64 Básica 99,2 1,28 1,30 1,82 S10 >1,64 Básica 94,9 1,26 1,32 1,78 S11 <1,62 Ácida 62,1 0,85 0,84 1,09 S12 <1,62 Ácida 69,4 0,86 0,84 1,10 S13 <1,62 Ácida 70,4 0,70 0,70 0,93 S14 <1,62 Ácida 53,3 0,69 0,69 0,93 S15 <1,62 Ácida 76,3 0,75 0,75 1,01 S16 <1,62 Ácida 61,8 0,60 0,63 0,84 S17 <1,62 Ácida 43,7 0,71 0,71 0,91

32 Slag Basic Slag Acid Slag

33 % de Calcário Cement + Limestone y = 0,987x R 2 = 0, % de Calcário - Rietveld

34 PF teórico Cement + Gypsum 7,0 6,5 6,0 5,5 R 2 = 0,9868 5,0 5,0 5,5 6,0 6,5 7,0 PF em laboratório

35 Cement + Fly ash Calcite Cement % Fly ash LiF

36 Fly ash variation

37 % Cinza Volante - Rietveld Cement + Fly ash F1-CV60i F1-CV50i F1-CV40i F1-CV30i F1-CV20i Cinza Volante Clínquer Calcário Fosfogesso F1-CV10i 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% y = 0,9699x R 2 = 0, % Cinza Volante CV1 inserida

38 Slag variation LiF Cement % Slag

39 Slag variation

40 % Escória-Rietveld Cement + Slag F3-E60i F3-E40i Escória Clínquer Calcário Fosfogesso F3-E20i 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% y = 1,0329x R 2 = 0, % Escória F2 inserida

41 amorphous portion calculated (wt.-%) Amorphous error Mixtures of crystalline and amorphous phases Every mixture was prepared and measured ten times :1 +/-2.0% error glass expected weight (wt.-%) Blended cements: amorphous and crystalline to ±2 wt%

42 Phases error Alite 65 wt.-% ± 2 wt.-% Belite 15 wt.-% ± 1.5 wt.-% Ferrite 6 wt.-% ± 0.6 wt.-% Aluminate 5 wt.-% ± 0.6 wt.-% Lime 1 wt.-% ± 0.3 wt.-% Periclase 1 wt.-% ± 0.3 wt.-% Gypsum 2 wt.-% ± 0.4 wt.-% Hemihydrate 1 wt.-% ± 0.3 wt.-% Anhydrite 1 wt.-% ± 0.3 wt.-% Calcite 1 wt.-% ± 0.3 wt.-% Portlandite 1 wt.-% ± 0.3 wt.-% Quartz 1 wt.-% ± 0.3 wt.-%

43 Problems in Sample Preparation

44 Sample preparation Oriented (002) Randomly (002) Why/When? Pressing Flat crystals Alite Gypsum Portlandite Clay minerals Mullite

45 Sample preparation Alite Common to gypsum 15s 30s 60s 120 s 180 s

46 Conclusion - XRD-Rietveld analysis is a fast and reproducible method - % of all clinker phases (different types of C 3 A and alkaline sulphates) - Quantification of amorphous in cement useful cements with pozzolanic materials - Higher correlation with cement between quantitative results and cement properties

47 Thank you!