Characterizations and Quantitative Estimation of Alkali-Activated Binder Paste from Microstructures

다국어 초록 (Multilingual Abstract)

Alkali-activated binder (AAB) is recently being considered as a sustainable alternative to portland cement (PC) due toits low carbon dioxide emission and diversion of industrial wastes and by-products such as fly ash and slag from landfills. In orderto comprehend the behavior of AAB, detailed knowledge on relations between microstructure and mechanical properties areimportant. To address the issue, a new approach to characterize hardened pastes of AAB containing fly ash as well as thosecontaining fly ash and slag was adopted using scanning electron microscopy (SEM) and energy dispersive X-ray spectramicroanalyses. The volume stoichiometries of the alkali activation reactions were used to estimate the quantities of the sodiumaluminosilicate (N–A–S–H) and calcium silicate hydrate (CSH) produced by these reactions. The 3D plots of Si/Al, Na/Al andCa/Si atom ratios given by the microanalyses were compared with the estimated quantities of CSH(S) to successfully determine theunique chemical compositions of the N–A–S–H and CSH(S) for ten different AAB at three different curing temperatures using aconstrained nonlinear least squares optimization formulation by general algebraic modeling system. The results show that thetheoretical and experimental quantities of N–A–S–H and CSH(S) were in close agreement with each other. The R2 values were0.99 for both alkali-activated fly ash and alkali-activated slag binders.

참고문헌 (Reference)

1 Breck, D. W, "Zeolite molecular sieves, structure, chemistry and use" Wiley 1974

2 Rees, C, "The role of solid silicates on the formation of geopolymers derived from coal ash" Department of Metallurgical and Materials Engineering, Indian Institute of Technology Madras 2004

3 Van Jaarsveld, J. G. S, "The physical and chemical characterisation of fly ash based geopolymers" University of Melbourne 2000

4 Chen, W, "The hydration of slag, part 1: Reaction models for alkali-activated slag" 42 : 428-443, 2007

5 Famy, C, "The C-S-H gel of Portland cement mortars: Part I. The interpretation of energy-dispersive X-ray microanalyses from scanning electron microscopy, with some observations on C-S-H, AFm and AFt phase compositions" 23 : 1389-1398, 2003

6 Barbosa, V. F. F, "Synthesis and thermal behaviour of potassium sialate geopolymers" 57 : 1477-1482, 2000

7 Fernandez-Jimenez, A, "Quantitative determination of phases in the alkaline activation of fly ash. Part II: Degree of reaction" 85 : 1960-1969, 2006

8 Talling, B, "Progress in cement and concrete: Mineral admixtures in cement and concrete" Akademia Books International 1995

9 Bazaara, M. S, "Nonlinear programming: Theory and algorithms" Wiley 2006

10 Kar, A, "Nondestructive characterizations of alkali activated fly ash and/or slag concrete" 9 (9): 52-74, 2013

11 Davidovits, J, "Mineral polymers and methods of making them. US Patent 4,349,386"

12 Skvara, F, "Microstructure of geopolymer materials based on fly ash" 50 : 208-215, 2006

13 Muzek, M. N, "Microstructural characteristics of geopolymers based on alkali-activated fly ash" 26 (26): 89-95, 2012

14 Lloyd, R. R, "Microscopy and microanalysis of inorganic polymer cements. 2: The gel binder" 44 (44): 620-631, 2009

15 Smilauer, V, "Micromechanical multiscale model for alkali activation of fly ash and metakaolin" 2011

16 Kar, A, "Microanalysis and optimization-based estimation of C-SH contents of cementitious systems containing fly ash and silica fume" 34 : 419-429, 2012

17 Rees, C. A, "Mechanisms and kinetics of gel formation in geopolymers" University of Melbourne 2007

18 De Silva, P, "Kinetics of geopolymerization: Role of Al2O3 and SiO2" 37 : 512-518, 2007

19 Kamhangrittirong, P, "Green binder technology development using fly ash based geopolymer" 2007

20 Provis, J. L, "Geopolymers: Structure, processing, properties and industrial applications" Woodhead; Boca Raton 2009

21 Davidovits, J, "Geopolymers: Inorganic polymeric new materials" 37 : 1633-1656, 1991

22 Davidovits, J, "Geopolymers of the first generation: SILIFACEProcess" 1988

23 Davidovits, J, "Geopolymers : Inorganic polymeric new materials" 16 : 91-139, 1994

24 Davidovits, J, "Geopolymeric reactions in the economic future of cements and concretes: world-wide mitigation of carbon dioxide emission" 111-121, 1999

25 Smith, J. W, "Geopolymeric building materials in third world countries" 1 : 89-92, 1988

26 Davidovits, J, "Geopolymer chemistry and properties" 1983

27 Rosenthal, R. E, "GAMS—A user guide" Gams Development Corporation 2008

28 Feng, X, "Estimation of the degree of hydration of blended cement pastes by a scanning electron microscopy point-count procedure" 34 (34): 1787-1793, 2004

29 Kar, A, "Estimation of C-S-H and calcium hydroxide for cement pastes containing slag and silica fume" 30 : 505-515, 2012

30 Lee, W. K. W, "Effects of anions on the formation of aluminosilicate gel in geopolymers" 41 (41): 4550-4558, 2002

31 Kupwade-Patil, K, "Effect of alkali silica reaction (ASR) in Geopolymer Concrete" 2011

32 Duxson, P, "Effect of alkali cations on aluminium incorporation in geopolymeric gels" 44 : 832-839, 2005

33 Sakulich, A. R, "Characterization of environmentallyfriendly alkali activated slag cements and ancient building materials" Drexel University 2009

34 Taylor, H. F. W, "Cement Chemistry" Thomas Telford 1997

35 Drud, A, "CONOPT user guide. Bagsvaerd, Denmark: ARKI Consulting and Development A/S"

36 ASTM C494 Type F, "Annual book of ASTM standards, concrete and aggregates, 04.02" American Society for Testing and Materials 2013

37 ASTM C33 M-13, "Annual book of ASTM standards, concrete and aggregates, 04.02" American Society for Testing and Materials 2013

38 ASTM 7777C618, "Annual book of ASTM standards, concrete and aggregates, 04.02" American Society for Testing and Materials 2013

39 ASTM C989, "Annual book of ASTM standards, concrete and aggregates, 04.02" American Society for Testing and Materials 2013

40 Fernandez-Jimenez, A, "Alkali-activated slag cements: Kinetic studies" 27 (27): 359-368, 1997

41 Shi, C, "Alkali-activated cements and concretes" Taylor & Francis 2006