Impact of Alkali Silica Reaction on Fly Ash-Based Geopolymer Concrete

This study reports the findings of an experimental investigation for alkali silica reaction (ASR) between reactive aggregates and the geopolymer matrix. Specimens were prepared using one Class C and two Class F fly ash stockpiles. Mechanical testing included potential reactivity of the aggregates via length change and compression test measurements, as per ASTM standards. Results suggest that the extent of ASR reaction due to the presence of reactive aggregates in fly ash-based geopolymer concretes is substantially lower than in the case of ordinary portland cement-based concrete, and well below the ASTM specified threshold. Furthermore, geopolymer concrete specimens appeared to undergo a densification process in the presence of alkali solutions, resulting in reduced permeability and increased mechanical strength. Utilizing ASR-vulnerable aggregates in the production of geopolymer concrete products could contribute to the economic appeal and sustainability of geopolymer binders in regions that suffer from insufficient local supply of high quality aggregates.

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

[2]  H. Brouwers,et al.  Alkali concentrations of pore solution in hydrating OPC , 2003 .

[3]  Sidney Diamond,et al.  A review of alkali-silica reaction and expansion mechanisms 1. Alkalies in cements and in concrete pore solutions , 1975 .

[4]  J. Davidovits.  Geopolymer chemistry and applications , 2008 .

[5]  Jack P. Moehle,et al.  "BUILDING CODE REQUIREMENTS FOR STRUCTURAL CONCRETE (ACI 318-11) AND COMMENTARY" , 2011 .

[6]  J. Gillott,et al.  Mechanism of alkali-silica reaction and the significance of calcium hydroxide , 1991 .

[7]  Olivier Coussy,et al.  Thermo-chemo-mechanics of ASR expansion in concrete structures , 2000 .

[8]  Wei Chen,et al.  Alkali binding in hydrated Portland cement paste , 2010 .

[9]  John L. Provis,et al.  Structural Evolution of Fly Ash Based Geopolymers in Alkaline Environments , 2008 .

[10]  J. Deventer,et al.  The effect of silica availability on the mechanism of geopolymerisation , 2011 .

[11]  D. Macphee,et al.  Effect of Alkalis on Fresh C-S-H Gels. FTIR Analysis , 2009 .

[12]  W. Aquino,et al.  The influence of metakaolin and silica fume on the chemistry of alkali-silica reaction products , 2001 .

[13]  M. Grutzeck,et al.  Zeolite formation in alkali-activated cementitious systems , 2004 .

[14]  E. Allouche,et al.  Factors affecting the suitability of fly ash as source material for geopolymers , 2010 .

[15]  P. Monteiro,et al.  Structural Investigations of Alkali Silicate Gels , 2005 .

[16]  E. Allouche,et al.  Effect of Alkali Silica Reaction ( ASR ) in Geopolymer Concrete , 2011 .

[17]  Bruno Godart,et al.  Estimation of the Residual Expansion of Concrete Affected by Alkali Silica Reaction , 2008 .

[18]  Erez N. Allouche,et al.  Mechanical Properties of Fly-Ash-Based Geopolymer Concrete , 2011 .

[19]  Á. Palomo,et al.  Effect of Calcium Additions on N-A-S-H Cementitious Gels , 2010 .

[20]  R. N. Swamy,et al.  Effect of Alkali-Silica Reaction on the Structural Behavior of Reinforced Concrete Beams , 1989 .

[21]  Frank Winnefeld,et al.  Alkali–Silica Reaction: the Influence of Calcium on Silica Dissolution and the Formation of Reaction Products , 2011 .

[22]  Ángel Palomo,et al.  Alkali–aggregate reaction in activated fly ash systems , 2007 .

[23]  Sidney Diamond,et al.  A review of alkali-silica reaction and expansion mechanisms 2. Reactive aggregates , 1976 .