Rheologica Acta

, Volume 53, Issue 10–11, pp 843–855 | Cite as

Observations on the rheological response of alkali activated fly ash suspensions: the role of activator type and concentration

  • Kirk Vance
  • Akash Dakhane
  • Gaurav Sant
  • Narayanan NeithalathEmail author
Original Contribution


This paper reports the influence of activator type and concentration on the rheological properties of alkali-activated fly ash suspensions. A thorough investigation of the rheological influences (yield stress and plastic viscosity) of several activator parameters, including: (i) the cation type and concentration of alkali hydroxide and (ii) the alkali-to-binder ratio (n) and silica modulus (Ms), and (iii) the volume of the activation solution, on the suspension rheology is presented. The results indicate a strong dependence on the cation and its concentration in the activation solution. The viscosity of the activation solution and the volumetric solution-to-powder ratio are shown to most strongly influence the plastic viscosity of the suspension. The suspension yield stress is predominantly influenced by the changes in fly ash particle surface charge and the ionic species in the activator. A shift from non-Newtonian to Newtonian flow behavior is noted in the case of silicate-based suspensions for Ms ≤ 1.5. This behavior, which is not observed at higher MS values, or when the fly ash is dispersed in hydroxide solutions or pure water, is hypothesized to be caused by colloidal siliceous species present in this system, or surface charge effects on the fly ash particles. Comparisons of the rheological response of alkali-activated suspensions to that of portland cement-water suspensions are also reported.


Geopolymer Rheology Fly ash Yield stress Plastic viscosity 



Ratio of Na2O in the activator to the total fly ash content


Ratio of SiO2-to-Na2O in the activator


Activation solution-to-powder ratio, by volume (Refer to the definition of activation solution in 2.1


Activation solution-to-binder ratio, by volume; binder implying fly ash here


Water-to-solids ratio, mass-based (Refer to the definition of solids in 2.1)


Water-to-cement ratio, mass-based, for OPC systems


Shear stress, Pa


Yield stress, Pa


Plastic viscosity, Pa.s


Apparent viscosity, Pa.s

\( \dot{\gamma} \)

Shear rate, s−1



The authors gratefully acknowledge the National Science Foundation (CMMI 1068985) and Arizona State University for the partial support of this research. The materials for this research were provided by Headwaters Resources and PQ Corporation, and are acknowledged. K.V. also acknowledges the Dean’s Fellowship from the Ira A. Fulton Schools of Engineering at Arizona State University (ASU). This research was conducted in the Laboratory for the Science of Sustainable Infrastructural Materials (LS-SIM) at ASU and the authors gratefully acknowledge the support that has made this laboratory possible. The contents of this paper reflect the views of the authors who are responsible for the facts and accuracy of the data presented herein, and do not necessarily reflect the views and policies of the funding agency, nor do the contents constitute a standard, specification, or a regulation.


  1. ASTM C109-13 (2013) Standard Test Method for Compressive Strength of Hydraulic Cement Mortars Using 2-in. Cube Specimens.Google Scholar
  2. ASTM C1738 - 11a (2011) Standard Practice for High-Shear Mixing of Hydraulic Cement Paste.Google Scholar
  3. Atzeni C, Massidda L, Sanna U (1985) Comparison between rheological models for portland cement pastes. Cem Concr Res 15:511–519CrossRefGoogle Scholar
  4. Banfill PFG (2006) Rheology of fresh cement and concrete. Rheol Rev 2006:61Google Scholar
  5. Barnes HA (1989) Shear-thickening (“dilatancy”) in suspensions of nonaggregating solid particles dispersed in Newtonian liquids. J Rheol 33:329CrossRefGoogle Scholar
  6. Barnes HA (1999) The yield stress—a review or “παντα ρει”—everything flows? J Non-Newtonian Fluid Mech 81:133–178CrossRefGoogle Scholar
  7. Barnes HA, Non-Newtonian I of, Mechanics F (2000) A handbook of elementary rheology. Univ. of Wales, Institute of Non-Newtonian Fluid MechanicsGoogle Scholar
  8. Bentz DP, Ferraris CF, Galler MA, Hansen AS, Guynn, JM (2012) Influence of particle size distributions on yield stress and viscosity of cement–fly ash pastes. Cem Concr Res 42:404–409Google Scholar
  9. Bernal SA, Mejía de Gutiérrez R, Provis JL (2012) Engineering and durability properties of concretes based on alkali-activated granulated blast furnace slag/metakaolin blends. Constr Build Mater 33:99–108CrossRefGoogle Scholar
  10. Bijen J (1996) Benefits of slag and fly ash. Constr Build Mater 10:309–314CrossRefGoogle Scholar
  11. Bingham EC (1922) Fluidity and plasticityGoogle Scholar
  12. Brady JF (1993) The rheological behavior of concentrated colloidal dispersions. J Chem Phys 99:567–581CrossRefGoogle Scholar
  13. Burgos-Montes O, Palacios M, Rivilla P, Puertas F (2012) Compatibility between superplasticizer admixtures and cements with mineral additions. Constr Build Mater 31:300–309CrossRefGoogle Scholar
  14. Callaghan PT (2008) Rheo NMR and shear banding. Rheol Acta 47:243–255CrossRefGoogle Scholar
  15. Cheng DC-H (1986) Yield stress: a time-dependent property and how to measure it. Rheol Acta 25:542–554CrossRefGoogle Scholar
  16. Criado M, Palomo A, Fernández-Jiménez A, Banfill PFG (2009) Alkali activated fly ash: effect of admixtures on paste rheology. Rheol Acta 48:447–455CrossRefGoogle Scholar
  17. Cyr M, Legrand C, Mouret M (2000) Study of the shear thickening effect of superplasticizers on the rheological behaviour of cement pastes containing or not mineral additives. Cem Concr Res 30:1477–1483CrossRefGoogle Scholar
  18. Davidovits J (1999) Chemistry of geopolymeric systems, terminology. Proceedings of Geopolymer 99:9–40Google Scholar
  19. Davidovits J (2005) Geopolymer chemistry and sustainable development. The poly (sialate) terminology: a very useful and simple model for the promotion and understanding of green-chemistry. Proc 2005 Geopolymer Conf. pp 9–15Google Scholar
  20. Fernández-Jiménez A, Garcia-Lodeiro I, Palomo A (2007) Durability of alkali-activated fly ash cementitious materials. J Mater Sci 42:3055–3065CrossRefGoogle Scholar
  21. Ferraris CF (1999) Measurement of the rheological properties of high performance concrete: State of the art report. J Res Natl Inst Stand Technol 104:461–478CrossRefGoogle Scholar
  22. Franks GV (2002) Zeta potentials and yield stresses of silica suspensions in concentrated monovalent electrolytes: Isoelectric point shift and additional attraction. J Colloid Interface Sci 249:44–51CrossRefGoogle Scholar
  23. Iler RK (1979) The chemistry of silica: solubility, polymerization, colloid and surface properties, and biochemistryGoogle Scholar
  24. Jeffrey DJ, Acrivos A (1976) The rheological properties of suspensions of rigid particles. AIChE J 22:417–432CrossRefGoogle Scholar
  25. Kamal MR, Mutel A (1985) Rheological properties of suspensions in Newtonian and Non-Newtonian fluids. J Polym Eng 5:293–382CrossRefGoogle Scholar
  26. Krieger IM, Dougherty TJ (1959) A mechanism for non-Newtonian flow in suspensions of rigid spheres. Trans Soc Rheol 3:137–152CrossRefGoogle Scholar
  27. Lootens D, Hébraud P, Lécolier E, Van Damme H (2004) Gelation, shear-thinning and shear-thickening in cement slurries. Oil Gas Sci Technol 59:31–40CrossRefGoogle Scholar
  28. Lowke D (2009) Interparticle Forces and Rheology of Cement Based Suspensions. Nanotechnol. Constr. 3. Springer, pp 295–301Google Scholar
  29. Mannheimer RJ (1983) Effect Of Slip On The Flow Properties Of Cement Slurries. Annu Meet Pap Div ProdGoogle Scholar
  30. Mikanovic N, Jolicoeur C (2008) Influence of superplasticizers on the rheology and stability of limestone and cement pastes. Cem Concr Res 38:907–919CrossRefGoogle Scholar
  31. Mueller S, Llewellin EW, Mader HM (2010) The rheology of suspensions of solid particles. Proc R Soc Math Phys Eng Sci 466:1201–1228CrossRefGoogle Scholar
  32. Nägele E (1986) The zeta-potential of cement: Part II: Effect of pH-value. Cem Concr Res 16:853–863CrossRefGoogle Scholar
  33. Nägele E, Schneider U (1989) The zeta-potential of blast furnace slag and fly ash. Cem Concr Res 19:811–820CrossRefGoogle Scholar
  34. Nehdi M, Rahman M-A (2004) Effect of geometry and surface friction of test accessory on oscillatory rheological properties of cement pastes. ACI Mater J 101:Google Scholar
  35. Palacios M, Houst YF, Bowen P, Puertas F (2009) Adsorption of superplasticizer admixtures on alkali-activated slag pastes. Cem Concr Res 39:670–677CrossRefGoogle Scholar
  36. Palomo A, Grutzeck MW, Blanco MT (1999) Alkali-activated fly ashes: a cement for the future. Cem Concr Res 29:1323–1329CrossRefGoogle Scholar
  37. Papo A, Piani L (2004) Effect of various superplasticizers on the rheological properties of Portland cement pastes. Cem Concr Res 34:2097–2101CrossRefGoogle Scholar
  38. Pasquino R, Nicodemi F, Vanzanella V et al (2013) A rheological phase diagram of additives for cement formulations. Rheol Acta 52:395–401CrossRefGoogle Scholar
  39. Poulesquen A, Frizon F, Lambertin D (2013) Rheological behavior of alkali-activated metakaolin during geopolymerization. Cem.-Based Mater Nucl Waste Storage. Springer, pp 225–238Google Scholar
  40. Provis JL, Van Deventer JSJ (2009) Geopolymers: Structure, processing, properties and industrial applications. Woodhead Cambridge, UKCrossRefGoogle Scholar
  41. Provis JL, Muntingh Y, Lloyd RR et al (2007) Will Geopolymers Stand the Test of Time? Dev Porous Biol Geopolymer Ceram Ceram Eng Sci Proc 235Google Scholar
  42. Puertas F, Fernández-Jiménez A (2003) Mineralogical and microstructural characterisation of alkali-activated fly ash/slag pastes. Cem Concr Compos 25:287–292CrossRefGoogle Scholar
  43. Qing-Hua C, Sarkar SL (1994) A study of rheological and mechanical properties of mixed alkali activated slag pastes. Adv Cem Based Mater 1:178–184CrossRefGoogle Scholar
  44. Ravikumar D, Neithalath N (2012) Reaction kinetics in sodium silicate powder and liquid activated slag binders evaluated using isothermal calorimetry. Thermochim. ActaGoogle Scholar
  45. Ravikumar D, Neithalath N (2012b) Effects of activator characteristics on the reaction product formation in slag binders activated using alkali silicate powder and NaOH. Cem Concr Compos 34:809–818CrossRefGoogle Scholar
  46. Saak AW, Jennings HM, Shah SP (2001) The influence of wall slip on yield stress and viscoelastic measurements of cement paste. Cem Concr Res 31:205–212CrossRefGoogle Scholar
  47. Santamarı´a-Holek I, Mendoza CI (2010) The rheology of concentrated suspensions of arbitrarily-shaped particles. J Colloid Interface Sci 346:118–126CrossRefGoogle Scholar
  48. Scales PJ, Johnson SB, Healy TW, Kapur PC (1998) Shear yield stress of partially flocculated colloidal suspensions. AIChE J 44:538–544CrossRefGoogle Scholar
  49. Schall P, van Hecke M (2009) Shear bands in matter with granularity. Annu Rev Fluid Mech 42:67CrossRefGoogle Scholar
  50. Škvára F, Kopecký L, Šmilauer V, Bittnar Z (2009) Material and structural characterization of alkali activated low-calcium brown coal fly ash. J Hazard Mater 168:711–720CrossRefGoogle Scholar
  51. Stebbins JF, Farnan I, Xue X (1992) The structure and dynamics of alkali silicate liquids: a view from NMR spectroscopy. Chem Geol 96:371–385CrossRefGoogle Scholar
  52. Svensson IL, Sjöberg S, Öhman L-O (1986) Polysilicate equilibria in concentrated sodium silicate solutions. J Chem Soc Faraday Trans 1(82):3635–3646CrossRefGoogle Scholar
  53. Sweeny KH, Geckler RD (1954) The rheology of suspensions. J Appl Phys 25:1135–1144CrossRefGoogle Scholar
  54. Termkhajornkit P, Nawa T (2004) The fluidity of fly ash-cement paste containing naphthalene sulfonate superplasticizer. Cem Concr Res 34:1017–1024CrossRefGoogle Scholar
  55. Tognonvi MT, Massiot D, Lecomte A et al (2010) Identification of solvated species present in concentrated and dilute sodium silicate solutions by combined 29Si NMR and SAXS studies. J Colloid Interface Sci 352:309–315CrossRefGoogle Scholar
  56. Vance, Kirk (2014) Early Age Characterization and Microstructural Features of Sustainable Binder Systems for Concrete. PhD Dissertation, Arizona State UniversityGoogle Scholar
  57. Vance K, Kumar A, Sant G, Neithalath N (2013) The rheological properties of ternary binders containing Portland cement, limestone, and metakaolin or fly ash. Cem Concr Res 52:196–207CrossRefGoogle Scholar
  58. Wijnen P, Beelen TPM, De Haan JW et al (1989) Silica gel dissolution in aqueous alkali metal hydroxides studied by 29Si NMR. J Non-Cryst Solids 109:85–94CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2014

Authors and Affiliations

  • Kirk Vance
    • 1
  • Akash Dakhane
    • 1
  • Gaurav Sant
    • 2
    • 3
  • Narayanan Neithalath
    • 1
    Email author
  1. 1.School of Sustainable Engineering and the Built EnvironmentArizona State UniversityTempeUSA
  2. 2.Department of Civil and Environmental EngineeringUniversity of California Los AngelesLos AngelesUSA
  3. 3.California Nanosystems InstituteUniversity of California Los AngelesLos AngelesUSA

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