Use of OPC to improve setting and early strength properties of low calcium fly ash geopolymer concrete cured at room temperature

Abstract Most previous works on fly ash based geopolymer concrete focused on concretes subjected to heat curing. Development of geopolymer concrete that can set and harden at normal temperature will widen its application beyond precast concrete. This paper has focused on a study of fly ash based geopolymer concrete suitable for ambient curing condition. A small proportion of ordinary Portland cement (OPC) was added with low calcium fly ash to accelerate the curing of geopolymer concrete instead of using elevated heat. Samples were cured in room environment (about 23 °C and RH 65 ± 10%) until tested. Inclusion of OPC as little as 5% of total binder reduced the setting time to acceptable ranges and caused slight decrease of workability. The early-age compressive strength improved significantly with higher strength at the age of 28 days. Geopolymer microstructure showed considerable portion of calcium-rich aluminosilicate gel resulting from the addition of OPC.

[1]  John L. Provis,et al.  The role of particle technology in developing sustainable construction materials , 2010 .

[2]  Aurélie Favier,et al.  Flow properties of MK-based geopolymer pastes. A comparative study with standard Portland cement pastes. , 2014, Soft matter.

[3]  John L. Provis,et al.  Effect of Calcium Silicate Sources on Geopolymerisation , 2008 .

[4]  Á. Palomo,et al.  Durability of alkali-activated fly ash cementitious materials , 2007 .

[5]  B. V. Rangan,et al.  Fly ash-based geopolymer concrete: study of slender reinforced columns , 2007 .

[6]  M. Weil,et al.  The influence of calcium content on the structure and thermal performance of fly ash based geopolymers , 2007 .

[7]  S. Martínez-Ramírez,et al.  OPC hydration with highly alkaline solutions , 2001 .

[8]  H. Damme,et al.  Why Does Concrete Set?: The Nature of Cohesion Forces in Hardened Cement-Based Materials , 2004 .

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

[10]  B. Vijaya Rangan,et al.  Low-Calcium fly ash-based geopolymer concrete: Long-term properties , 2006 .

[11]  Á. Palomo,et al.  Compatibility studies between N-A-S-H and C-A-S-H gels. Study in the ternary diagram Na2O–CaO–Al2O3–SiO2–H2O , 2011 .

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

[13]  Prabir Sarker,et al.  Effect of GGBFS on setting, workability and early strength properties of fly ash geopolymer concrete cured in ambient condition , 2014 .

[14]  Surendra P. Shah,et al.  Effects of curing temperature and NaOH addition on hydration and strength development of clinker-free CKD-fly ash binders , 2004 .

[15]  Keun-Hyeok Yang,et al.  Assessment of CO2 reduction of alkali-activated concrete , 2013 .

[16]  Zhitong Yao,et al.  A review of the alumina recovery from coal fly ash, with a focus in China , 2014 .

[17]  A. Fernández-Jiménez,et al.  Opc-fly ash cementitious systems: study of gel binders produced during alkaline hydration , 2007 .

[18]  J. Deventer,et al.  The coexistence of geopolymeric gel and calcium silicate hydrate at the early stage of alkaline activation , 2005 .

[19]  P. Sarker,et al.  Fracture behaviour of heat cured fly ash based geopolymer concrete , 2013 .

[20]  K. MacKenzie,et al.  Structure and mechanical properties of aluminosilicate geopolymer composites with Portland cement and its constituent minerals , 2010 .

[21]  P. Sarker.  Analysis of geopolymer concrete columns , 2009 .

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

[23]  Chai Jaturapitakkul,et al.  NaOH-activated ground fly ash geopolymer cured at ambient temperature , 2011 .

[24]  Djwantoro Hardjito,et al.  Behaviour and Strength of Reinforced Fly Ash-Based Geopolymer Concrete Beams , 2005 .

[25]  Kiatsuda Somna,et al.  Effect of External and Internal Calcium in Fly Ash on Geopolymer Formation , 2011 .

[26]  J. Ideker,et al.  Advances in alternative cementitious binders , 2011 .

[27]  Prabir Sarker,et al.  Bond strength of reinforcing steel embedded in fly ash-based geopolymer concrete , 2011 .

[28]  A. Rashad.  A comprehensive overview about the influence of different admixtures and additives on the properties of alkali-activated fly ash , 2014 .

[29]  M. Blanco-Varela,et al.  Alkaline Activation of Metakaolin: Effect of Calcium Hydroxide in the Products of Reaction , 2004 .

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

[31]  Ángel Palomo,et al.  Alkali activation of fly ash: Effect of the SiO2/Na2O ratio Part I: FTIR study , 2007 .

[32]  Phillip Frank Gower Banfill,et al.  Properties of alkali-activated fly ashes determined from rheological measurements , 2005 .

[33]  S. Martínez-Ramírez,et al.  Microstructure studies on Portland cement pastes obtained in highly alkaline environments , 2001 .