The document presents a multi-scale study of calcium leaching in high performance concrete. It uses a variety of techniques including mechanical testing, calorimetry, porosimetry, nanoindentation, NMR, and microscopy to examine concrete at multiple scales from macro to nano. The addition of silica nanoparticles is found to reduce calcium leaching by refining pore structure and altering the composition and structure of calcium silicate hydrates in the cement paste.

1. Multi-scale study of the fibre-matrix interface and calcium leaching in high performance concrete Juan J. Gaitero 2008

2. I wanna be a researcher

3. What’s a PhD. Thesis? Doctoral thesis 2008 ?

4. A thesis is not studying…

5. … is learning

6. A thesis is not the solution…

7. the problem … is solving

8. A thesis is not the results… A thesis is not the results… 0 100 200 300 400 Thousands of Years Before Present CO 2 Source: Petit et al. 1999 to 3310m Temperature

9. … is the conclusions GLOBAL WARMING

10. What do I need ?

11. Knowledge

12. October 2002

13. October 2002

14. October 2002

15. Now Now Now Now Now

16. MACRO -scale >1mm 20 mm

17. Micro-scale 20  m

18. Nano - scale HD-CSH LD-CSH 5 nm

19. Nano - scale Calcium Hidrogen Silicon Oxygen

20. Porosity 0 1 2 3 4 5 6 7 8 9 10 (×1 0 -1 mm)

22. Problems: Fibre push-in test Calcium leaching (2004-2008) (2003)

24. 0 10 20 30 40 50 60 0 250 500 750 1000 1250 Displacement (nm) Load (mN) Loading Reloading

26. 0 20 40 60 0 200 400 600 800 1000 Displacement (nm) Load (mN) Total Disp. Penetration Sliding

27. 0 50 100 150 200 250 Sliding displacement (nm) Load (mN) 0 20 40 60 80 100 120 Model 1:  =33.1 MPa;  u =32.0 MPa; F d = 0.0 mN Model 2:  =35.8 MPa; F d =7.1 mN ; F r =3.5 mN Model 3:  =28.8 MPa;  S =35.0 MPa;  = 0.82 Experimental

32. Conclusions: Interesting technique Good models Experimental problems

33. Conclusions: Interesting technique Good models Experimental problems

34. Conclusions: Interesting technique Good models Experimental problems

35. Conclusions: Interesting technique Good models Experimental problems

36. Problems: Fibre push-in test Calcium leaching (2003) (2004-2008)

37. Intact Degraded Lixiviado de calcio

38. It is real

39. Silica nanoparticles: Purity Size Reactivity Availability pH

40. 10 Nanosilicas + 2 Cements X Several Formulations = > 1000 Specimens

41. Samples 1x1x6cm Cem I - 52.5R; w/c=0.4 6 wt.% of nanosilica 4 nanosilicas Dry Powder 95 ----------- ---- 1400 Nyasil 20 Colloid. Disp. 40 Na 2 O 9.5 20 Bindzil 40/170 Colloid. Disp. 20 NH 3 10 120 Aerodisp W7520 Colloid. Disp. 45 Na 2 O 10 30 Levasil 100/45% Presentation SiO2 content (wt.%) Estabilizing agent pH Particle size (nm) Comercial nanosilica

42. Day 0: Mixing & casting. Day 1: Demoulding Immersion in CaO solution. Tests Day 7: Control tests. Day 28: Reference tests Immersion in NH 4 NO 3 6M. Day 28+9, 28+21, 28+42, 28+63: Study.

43. Multi-scale approach

44. Complementary Available Useful Techniques

47. Time Evolution Length Scale

48. Hydration Degradation Time Evolution Length Scale

49. Hydration Degradation Macro-scale Atomic-scale Macro-scale Time Evolution Length Scale

50. Hydration Degradation Macro-scale Atomic-scale Macro-scale Time Evolution Length Scale

51. Measured by Jeffrey J. Thomas, ACBM (USA) Reference Nanosilica 3 wt.% Nanosilica 6 wt.% Calorimetry

52. Reference Nanosilica 1 Day 7 Days 28 Days 25 52 67 39 70 85 Compressive Strength (MPa)

53. Reference Nanosilica 1 Day 7 Days 28 Days 25 52 67 39 70 85 Compressive Strength (MPa)

54. Pore Volume (ml/kg) 120 1 Day 28 Days 100 60 30 Reference Nanosilica

55. Peak Area (cts × º2q) 1 Day 7 Days 28 Days 6 9 13 11 17 20 Reference Nanosilica

56. 6 wt.% Nanoindentation Collaboration with Prof. Shah, ACBM (USA) 18 wt.% 6wt% Nanosilica Rel. Vol. E(GPa) Rel. Vol. E(GPa) Property 39 19 44 17 LD-CSH 50 27 37 24 HD-CSH

57. 6 wt.% Nanoindentation Collaboration with Prof. Shah, ACBM (USA) 18 wt.% 6wt% Nanosilica Rel. Vol. E(GPa) Rel. Vol. E(GPa) Property 39 19 44 17 LD-CSH 50 27 37 24 HD-CSH

58. 6 wt.% Nanoindentation Collaboration with Prof. Shah, ACBM (USA) 18 wt.% 6wt% Nanosilica Rel. Vol. E(GPa) Rel. Vol. E(GPa) Property 39 19 44 17 LD-CSH 50 27 37 24 HD-CSH

59. 29 Si MAS-NMR Calcium Hidrogen Silicon Oxygen

60. -120 -110 -100 -90 -80 -70 -130 Q 0 Q 1 Q 2 Q 3 O H S i O H H O H O O S i O H O H O O H S i O H O H S i O H H O H O O H S i O H O H O O S i O H O O H S i O H O H S i O H H O H O O H S i O H O H O O H S i O H O O S i O O S i S i O H H O O H S i H O H O H O O H O H H O -60 Q 4

61. 28 Days 1 Day Reference Nanosilica Q 0 Q 1 Q 2 Q 0 Q 1 Q 2 Q 4 -120 -100 -80 -60 -120 -100 -80 -60

62. 28 Days 1 Day Reference Nanosilica Q 0 Q 1 Q 2 Q 0 Q 1 Q 2 Q 4 -120 -100 -80 -60 -120 -100 -80 -60

63. 28 Days 1 Day Reference Nanosilica Q 0 Q 1 Q 2 Q 0 Q 1 Q 2 Q 4 -120 -100 -80 -60 -120 -100 -80 -60

64. 28 Days 1 Day Reference Nanosilica Q 0 Q 1 Q 2 Q 0 Q 1 Q 2 Q 4 -120 -100 -80 -60 -120 -100 -80 -60

65. Hydration Degradation Macro-scale Atomic-scale Macro-scale Time Evolution Length Scale

66. Hydration Degradation Macro-scale Atomic-scale Macro-scale Time Evolution Length Scale

67. Reference Nanosilica Compressive Strength (MPa) 85 67 74 0 Days 9 Days 21 Days 63 Days 16 24 10 21 7

68. Reference Nanosilica Compressive Strength (MPa) 85 67 74 0 Days 9 Days 21 Days 63 Days 16 24 10 21 7

69. Reference Nanosilica Compressive Strength (MPa) 85 67 74 0 Days 9 Days 21 Days 63 Days 16 24 10 21 7

70. Pore Volume (ml/kg) Reference Nanosilica 0 Days 9 Days 21 Days 63 Days 602 350 31 60 45 356 292 526

71. Pore Volume (ml/kg) Reference Nanosilica 0 Days 9 Days 21 Days 63 Days 602 350 31 60 45 356 292 526

72. Pore Volume (ml/kg) Reference Nanosilica 0 Days 9 Days 21 Days 63 Days 602 350 31 60 45 356 292 526

73. Strength vs. Porosity 0 0 0,2 0,4 0,6 0,8 Pore volume (ml/g) Reference Nanosilica 40 80 120 Strength (MPa)

74. 0 Days 9 Days 21 Days 63 Days C/S Reference Nanosilica 3.2 2.4 1.4 2.3 0.9 1.0 0.7 0.9

75. 0 Days 9 Days 21 Days 63 Days C/S Reference Nanosilica 3.2 2.4 1.4 2.3 0.9 1.0 0.7 0.9

76. 0 Days 9 Days 21 Days 63 Days C/S Reference Nanosilica 3.2 2.4 1.4 2.3 0.9 1.0 0.7 0.9

77. 0 Days 9 Days 21 Days 63 Days C/S Reference Nanosilica 3.2 2.4 1.4 2.3 0.9 1.0 0.7 0.9

78. 0 0,2 0,4 0,6 0,8 0 0,5 1 1,5 2 2,5 3 3,5 C/S Porosity (ml/g) Porosity vs. C/S Reference Nanosilica

79. Strength vs. C/S 0 25 50 75 100 0 0,5 1 1,5 2 2,5 3 3,5 C/S Strength (MPa) Reference Nanosilica

80. E (GPa) Reference Nanosilica Nanoindentation Measured by Wenzhong Zhu, ACM (UK) 7.1-24 4.6-14 42 26 20 0 3.6 2.3 42 27 19 0 HD-CSH LD-CSH Deg. Time (Days)

81. E (GPa) Reference Nanosilica Nanoindentation Measured by Wenzhong Zhu, ACM (UK) 7.1-24 4.6-14 42 26 20 0 3.6 2.3 42 27 19 0 HD-CSH LD-CSH Deg. Time (Days)

82. E (GPa) Reference Nanosilica Nanoindentation Measured by Wenzhong Zhu, ACM (UK) 7.1-24 4.6-14 42 26 20 0 3.6 2.3 42 27 19 0 HD-CSH LD-CSH Deg. Time (Days)

83. 0 0,5 1 0 2 4 6 8 10 Position (mm) Degraded Intermediate Undegraded 0 1 C/S 0,5 Reference Nanosilica

84. 29 Si MAS-NMR Q 0 Q 1 Q 2 Reference 0 Days -120 -100 -80 -60

85. 29 Si MAS-NMR Q 0 Q 1 Q 2 Q 3 Reference 9 Days -120 -100 -80 -60

86. 29 Si MAS-NMR Q 0 Q 1 Q 2 Q 3 Reference 21 Days -120 -100 -80 -60

87. Reference 29 Si MAS-NMR Q 1 Q 2 Q 3 42 Days -120 -100 -80 -60

88. Calcium Hidrogen Silicon Oxygen

92. 29 Si MAS-NMR Q 0 Q 1 Q 2 0 Days Nanosilica -120 -100 -80 -60

93. 29 Si MAS-NMR Q 0 Q 1 Q 2 9 Days Nanosilica -120 -100 -80 -60

94. 29 Si MAS-NMR Q 0 Q 1 Q 2 Q 3 21 Days Nanosilica -120 -100 -80 -60

95. 42 Days Nanosilica 29 Si MAS-NMR -120 -100 -80 -60 Q 0 Q 1 Q 2 Q 3

96. Conclusion

101. I wanna be a researcher

102. Conclusion Knwoledge

105. Future Work

107. Reduction of the calcium leaching rate of cement paste by addition of silica nanoparticles , Cem. Concr. Res., 38 (8-9) 1112-1118 (2008) AFM study of the early corrosion of a high strength steel in a diluted sodium chloride solution , Cor. Sci., 50 (7) 1820-1824 (2008) Silica nanoparticle addition to control the calcium-leaching in cement-based materials , Physica Status Solidi (a), 203 (6) 1313-1318 (2006) Atomic force microscopy and nanoindentation of cement pastes with nanotube dispersion , Phys. Status Solidi (A), 203 (6) 1076-1081 (2006) Multi-scale approach to the study of cement pastes: calcium leaching, a case of study , (Submitted)

108. Reduction of the calcium leaching rate of cement paste by addition of silica nanoparticles , Cem. Concr. Res., 38 (8-9) 1112-1118 (2008) AFM study of the early corrosion of a high strength steel in a diluted sodium chloride solution , Cor. Sci., 50 (7) 1820-1824 (2008) Silica nanoparticle addition to control the calcium-leaching in cement-based materials , Physica Status Solidi (a), 203 (6) 1313-1318 (2006) Atomic force microscopy and nanoindentation of cement pastes with nanotube dispersion , Phys. Status Solidi (A), 203 (6) 1076-1081 (2006) Multi-scale approach to the study of cement pastes: calcium leaching, a case of study , (Submitted) [email_address] www.nanoc.info www.labein.es