Impact of activator chemistry on permeability of alkali-activated slags

Durability of alkali-activated slags has been assessed by measuring the permeability using the beam-bending technique. This nondestructive technique obtains permeability values by measuring the hydrodynamic load relaxation curve of a saturated slender beam of solid paste placed in three-point bending. The impact of activator selection on the permeability of alkali-activated slags has been assessed together with the effects of water-to-precursor ratio, revealing that free silica in the activating solution is the dominant factor controlling permeability. The permeability results have been correlated with nitrogen sorption and mercury intrusion porosimetry to elucidate the percolated pore size controlling permeability. Comparison with existing beam-bending results for ordinary portland cement (OPC) paste shows that alkali-activated slags can be synthesized with permeability having the same order of magnitude as for OPC, indicating that certain alkali-activated slags are as resistant as OPC to ingress of solutions associated with deterioration processes.

[1]  John L. Provis,et al.  Durability of Alkali‐Activated Materials: Progress and Perspectives , 2014 .

[2]  Jie Zhang,et al.  Comparison of methods for arresting hydration of cement , 2011 .

[3]  George W. Scherer,et al.  New Methods to Measure Liquid Permeability in Porous Materials , 2007 .

[4]  Waltraud M. Kriven,et al.  Formation of ceramics from metakaolin-based geopolymers , 2009 .

[5]  P. Sipos,et al.  Viscosities and Densities of Highly Concentrated Aqueous MOH Solutions (M+ = Na+, K+, Li+, Cs+, (CH3)4N+) at 25.0 °C , 2000 .

[6]  G. Scherer.  Bending of gel beams: method for characterizing elastic properties and permeability , 1992 .

[7]  G. Scherer,et al.  Measuring Permeability of Rigid Materials by a Beam‐Bending Method: III, Cement Paste , 2002 .

[8]  N. B. Milestone,et al.  Probing the microstructure and water phases in composite cement blends , 2007 .

[9]  Ángel Palomo,et al.  Immobilization of cesium in alkaline activated fly ash matrix , 2005 .

[10]  J. Deventer,et al.  Understanding the relationship between geopolymer composition, microstructure and mechanical properties , 2005 .

[11]  G. Scherer.  Relaxation of a viscoelastic gel bar: I. theory , 1994 .

[12]  J. Deventer,et al.  Geopolymerisation kinetics. 3. Effects of Cs and Sr salts , 2008 .

[13]  Francisca Puertas,et al.  Pore solution in alkali-activated slag cement pastes. Relation to the composition and structure of calcium silicate hydrate , 2004 .

[14]  Maria C.G. Juenger,et al.  The use of nitrogen adsorption to assess the microstructure of cement paste , 2001 .

[15]  John L. Provis,et al.  Pore solution composition and alkali diffusion in inorganic polymer cement , 2010 .

[16]  J. Plank,et al.  Working mechanism of methyl hydroxyethyl cellulose (MHEC) as water retention agent , 2012 .

[17]  M. Janich,et al.  Size distribution of colloidal silica in sodium silicate solutions investigated by dynamic light scattering and viscosity measurements. , 2003, Journal of colloid and interface science.

[18]  E. Samson,et al.  Durability of concrete — Degradation phenomena involving detrimental chemical reactions , 2008 .

[19]  Pavel Rovnaník,et al.  Effect of curing temperature on the development of hard structure of metakaolin-based geopolymer , 2010 .

[20]  George W. Scherer,et al.  Measuring permeability and stress relaxation of young cement paste by beam bending , 2003 .

[21]  S. Bhattacharja,et al.  Microstructure determination of cement pastes by NMR and conventional techniques , 1993 .

[22]  J. Prévost,et al.  Bending of a poroelastic beam with lateral diffusion , 2009 .

[23]  J. Sanjayan,et al.  Microcracking and strength development of alkali activated slag concrete , 2001 .

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

[25]  S. Bernal,et al.  Geopolymers and Related Alkali-Activated Materials , 2014 .

[26]  John L. Provis,et al.  Technical and commercial progress in the adoption of geopolymer cement , 2012 .

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

[28]  John L. Provis,et al.  Drying-induced changes in the structure of alkali-activated pastes , 2013, Journal of Materials Science.

[29]  K. Scrivener,et al.  Densification of C–S–H Measured by 1H NMR Relaxometry , 2013 .

[30]  H. Manzano,et al.  A model for the C-A-S-H gel formed in alkali-activated slag cements , 2011 .

[31]  G. Scherer.  Bending a gel rod with an impermeable surface , 1996 .

[32]  G. Scherer.  Measuring Permeability of Rigid Materials by a Beam‐Bending Method: I, Theory , 2004 .

[33]  John L. Provis,et al.  Chemical Research and Climate Change as Drivers in the Commercial Adoption of Alkali Activated Materials , 2010 .

[34]  G. Scherer,et al.  Measuring Permeability of Rigid Materials by a Beam-Bending Method: II, Porous Glass , 2004 .

[35]  Kenneth J. D. MacKenzie,et al.  Synthesis, characterisation and thermal behaviour of lithium aluminosilicate inorganic polymers , 2010 .

[36]  Karen L. Scrivener,et al.  Innovation in use and research on cementitious material , 2008 .