The shrinkage of alkali activated fly ash

Abstract In this study, the autogenous and drying shrinkage of alkali activated fly ash (AAFA) pastes prepared with different contents of sodium silicate solution are reported. A higher amount of both Na 2 O and SiO 2 resulted in a larger autogenous and drying shrinkage. Although a large autogenous shrinkage was obtained during the first 1–3 days, cracking was not observed in the ellipse ring tests. In AAFA pastes, water was not a reactant, but mainly acted as a medium. The experiment results indicate that the autogenous shrinkage of AAFA is not caused by the well-known self-desiccation process that happened in cement paste, but related to the continuous reorganization and polymerization of the aluminosilicate gel structure. AAFA pastes with a larger drying shrinkage exhibited a higher weight loss. The different microstructures lead to the different drying shrinkage of these AAFA mixtures.

[1]  J. Provis,et al.  29Si NMR study of structural ordering in aluminosilicate geopolymer gels. , 2005, Langmuir : the ACS journal of surfaces and colloids.

[2]  Ángel Palomo,et al.  Alkali-activated fly ashes: A cement for the future , 1999 .

[3]  Á. Palomo,et al.  Effect of the SiO2/Na2O ratio on the alkali activation of fly ash. Part II: 29Si MAS-NMR Survey , 2008 .

[4]  John L. Provis,et al.  Microscopy and microanalysis of inorganic polymer cements. 2: the gel binder , 2009, Journal of Materials Science.

[5]  J. Provis,et al.  In situ ATR-FTIR study of the early stages of fly ash geopolymer gel formation. , 2007, Langmuir : the ACS journal of surfaces and colloids.

[6]  John L. Provis,et al.  Microscopy and microanalysis of inorganic polymer cements. 1: remnant fly ash particles , 2009, Journal of Materials Science.

[7]  G. Ye,et al.  The pore structure and permeability of alkali activated fly ash , 2013 .

[8]  J. Deventer,et al.  Geopolymer technology: the current state of the art , 2007 .

[9]  C. Brinker,et al.  Sol-Gel Science: The Physics and Chemistry of Sol-Gel Processing , 1990 .

[10]  J. Deventer,et al.  Do Geopolymers Actually Contain Nanocrystalline Zeolites? A Reexamination of Existing Results , 2005 .

[11]  S. Martínez-Ramírez,et al.  Alkali-activated fly ash/slag cements: Strength behaviour and hydration products , 2000 .

[12]  J. Sanjayan,et al.  Effect of elevated temperature curing on properties of alkali-activated slag concrete , 1999 .

[13]  Zonglian He,et al.  Influence of alkali on restrained shrinkage behavior of cement-based materials , 2005 .

[14]  Will Hansen,et al.  Drying Shrinkage Mechanisms in Portland Cement Paste , 1987 .

[15]  Fernando Pacheco-Torgal,et al.  Alkali-activated binders: A review. Part 2. About materials and binders manufacture , 2008 .

[16]  E. W. Washburn.  The Dynamics of Capillary Flow , 1921 .

[17]  C. Shi,et al.  New cements for the 21st century: The pursuit of an alternative to Portland cement , 2011 .

[18]  Jeffrey J. Thomas,et al.  A colloidal interpretation of chemical aging of the C-S-H gel and its effects on the properties of cement paste , 2006 .

[19]  P. Lura,et al.  Measuring techniques for autogenous strain of cement paste , 2007 .

[20]  D. A. Petrash,et al.  Contact angles of mercury on various surfaces and the effect of temperature , 1967 .

[21]  J.S.J. van Deventer,et al.  Geopolymerisation kinetics. 2. Reaction kinetic modelling , 2007 .

[22]  Caijun Shi,et al.  Strength, pore structure and permeability of alkali-activated slag mortars , 1996 .

[23]  J. Deventer,et al.  Geopolymers : structure, processing, properties and industrial applications , 2009 .

[24]  B. Vijaya Rangan,et al.  ON THE DEVELOPMENT OF FLY ASH-BASED GEOPOLYMER CONCRETE , 2004 .

[25]  Ángel Palomo,et al.  Composition and Microstructure of Alkali Activated Fly Ash Binder: Effect of the Activator , 2005 .

[26]  Wellington Longuini Repette,et al.  Drying and autogenous shrinkage of pastes and mortars with activated slag cement , 2008 .

[27]  T. L. Brownyard,et al.  Studies of the Physical Properties of Hardened Portland Cement Paste , 1946 .

[28]  A. Fernández-Jiménez,et al.  New Cementitious Materials Based on Alkali-Activated Fly Ash: Performance at High Temperatures , 2008 .

[29]  J. Deventer,et al.  The Role of Inorganic Polymer Technology in the Development of ‘Green Concrete’ , 2007 .

[30]  Ángel Palomo,et al.  Engineering Properties of Alkali-Activated Fly Ash Concrete , 2006 .

[31]  J. Sanjayan,et al.  Workability and mechanical properties of alkali activated slag concrete , 1999 .

[32]  Á. Palomo,et al.  Microstructure Development of Alkali-Activated Fly Ash Cement: A Descriptive Model , 2005 .

[33]  Frank Collins,et al.  Effect of pore size distribution on drying shrinkage of alkali-activated slag concrete , 2000 .

[34]  Ángel Palomo,et al.  An XRD Study of the Effect of the SiO2/Na2O Ratio on the Alkali Activation of Fly Ash , 2007 .

[35]  K. Breugel,et al.  Autogenous shrinkage in high-performance cement paste: An evaluation of basic mechanisms , 2003 .

[36]  Sidney Diamond,et al.  Mercury porosimetry: An inappropriate method for the measurement of pore size distributions in cement-based materials , 2000 .

[37]  G. Ye,et al.  The effect of activating solution on the mechanical strength, reaction rate, mineralogy, and microstructure of alkali-activated fly ash , 2012, Journal of Materials Science.

[38]  A. Allahverdi,et al.  SULFURIC ACID ATTACK ON HARDENED PASTE OF GEOPOLYMER CEMENTS PART 1. MECHANISM OF CORROSION AT RELATIVELY HIGH CONCENTRATIONS , 2005 .

[39]  J. Deventer,et al.  MgO content of slag controls phase evolution and structural changes induced by accelerated carbonation in alkali-activated binders , 2014 .

[40]  G. Scherer.  Structure and properties of gels , 1999 .

[41]  John L. Provis,et al.  Spatial distribution of pores in fly ash-based inorganic polymer gels visualised by Wood’s metal intrusion , 2009 .

[42]  Á. Palomo,et al.  The role played by the reactive alumina content in the alkaline activation of fly ashes , 2006 .

[43]  J. Provis,et al.  Attenuated total reflectance fourier transform infrared analysis of fly ash geopolymer gel aging. , 2007, Langmuir : the ACS journal of surfaces and colloids.

[44]  Petr Hlaváček,et al.  Micromechanical multiscale model for alkali activation of fly ash and metakaolin , 2011, Journal of Materials Science.