geopolymer-book-chapter1 (1).pdf

Geopolymer Chemistry and Applications

3rd edition

Joseph Davidovits

2008, 2011 Joseph Davidovits

ISBN: 9782951482050

3rd edition, july 2011.

Published by:Institut Gopolymre16 rue GalileF-02100 Saint-QuentinFranceWeb: www.geopolymer.org

Written and edited by:Joseph DavidovitsWeb: www.davidovits.info

All Rights Reserved. No part of this publication may be reproduced or transmitted inany form or by any means, electronic or mechanical, including photocopy, recording orany other information storage and retrieval system, without prior permission in writingfrom the publisher.Tous Droits Rservs. Aucune partie de cette publication ne peut tre reproduite sousaucune forme ou par aucun moyen, lectronique ou mcanique, incluant la photocopie,lenregistrement ou par systme de stockage dinformations ou de sauvegarde, sans lapermission crite pralable de lditeur.

Contents

I Polymers and Geopolymers 1

1 Introduction 31.1 Geopolymer technology . . . . . . . . . . . . . . . . . . . . . . . 4

1.1.1 The invention of the first mineral resin, October 1975 . . 61.2 The scope of the book . . . . . . . . . . . . . . . . . . . . . . . . 111.3 Early observations . . . . . . . . . . . . . . . . . . . . . . . . . . 111.4 Phosphate-based geopolymer . . . . . . . . . . . . . . . . . . . . 14

1.4.1 Phosphate geopolymers . . . . . . . . . . . . . . . . . . . 141.4.2 High-molecular phosphate-based geopolymers: cristo-

balitic AlPO4 . . . . . . . . . . . . . . . . . . . . . . . . 151.5 Organic-mineral geopolymers . . . . . . . . . . . . . . . . . . . . 16

1.5.1 Silicone . . . . . . . . . . . . . . . . . . . . . . . . . . . . 161.5.2 Humic-acid based: kerogen geopolymer . . . . . . . . . . 16

2 The mineral polymer concept: silicones and geopolymers 212.1 The polymeric character of silicones . . . . . . . . . . . . . . . . 222.2 The dispute over ionic or covalent bonding in silicates . . . . . . 232.3 Covalent bonding in alumino-silicates / silico-aluminates . . . . . 282.4 Tetra-coordinated Al or tetra-valent Al? . . . . . . . . . . . . . . 292.5 Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

2.5.1 Poly(siloxo) / poly(siloxonate) / poly(silanol) . . . . . . 302.5.2 Poly(sialate) . . . . . . . . . . . . . . . . . . . . . . . . . 32

2.6 Polymeric character of geopolymers: geopolymeric micelle . . . . 34

3 Macromolecular structure of natural silicates and aluminosil-icates 393.1 Silicate ionic and covalent structural representations . . . . . . . 403.2 Ortho-silicate, 1[SiO4], ortho-siloxonate, Zircon ZrSiO4 . . . . . . 423.3 Di-silicate, di-siloxonate, Epidote . . . . . . . . . . . . . . . . . . 433.4 Tri-silicate, tri-siloxonate, ring silicate, Benitoite . . . . . . . . . 433.5 Tetra-silicate, 4[SiO4], ring silicate [Si4O12] . . . . . . . . . . . . 443.6 Hexa-silicate, hexa-siloxonate, ring silicate, Beryl . . . . . . . . . 443.7 Linear poly-silicate, poly(siloxonate), chain silicate, Pyroxene,

Wollastonite . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 453.8 Branched poly-silicate, poly(siloxonate), ribbon structure, Am-

phibole [Si4O11]n . . . . . . . . . . . . . . . . . . . . . . . . . . . 47

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3.9 Sheet silicate, [Si2O5]n, 2D-poly(siloxo), composite sheet . . . . . 483.9.1 Kaolinite, poly(siloxo-aluminumhydroxyl) . . . . . . . . 493.9.2 Pyrophillite Al4(OH)4[Si8O20], poly(siloxo-intra-sialate) 493.9.3 Muscovite K2Al4[Si6Al2O20](OH)4, poly(siloxo-intra-sialate) 50

3.10 Other sheet silicates, Melilite, Gehlenite, Akermanite, pentago-nal arrangement. . . . . . . . . . . . . . . . . . . . . . . . . . . . 51

3.11 Framework silicate, Quartz, Tridymite, SiO2 . . . . . . . . . . . . 523.11.1 Structure of Quartz . . . . . . . . . . . . . . . . . . . . . 523.11.2 Structure of Tridymite . . . . . . . . . . . . . . . . . . . 53

3.12 Framework silicate, Nepheline Na[AlSiO4] and Kalsilite K[AlSiO4] 543.13 Framework silicate, Leucite K[AlSi2O6] . . . . . . . . . . . . . . . 543.14 Framework silicate, Feldspar double-crankshaft chain [(Si,Al)4O8]n 55

3.14.1 Anorthite Ca[Al2Si2O8] . . . . . . . . . . . . . . . . . . . 563.14.2 Sanidine K[AlSi3O8] . . . . . . . . . . . . . . . . . . . . 56

3.15 Framework silicate, Feldspathoid, Sodalite Na[AlSiO4] . . . . . . 573.16 Framework silicate, zeolite group . . . . . . . . . . . . . . . . . . 58

II The synthesis of alumino-silicate mineral geopoly-mers 61

4 Scientific Tools, X-rays, FTIR, NMR 634.1 X-ray diraction . . . . . . . . . . . . . . . . . . . . . . . . . . . 634.2 FTIR, infra-red spectroscopy . . . . . . . . . . . . . . . . . . . . 684.3 MAS-NMR spectroscopy . . . . . . . . . . . . . . . . . . . . . . . 70

4.3.1 27Al MAS-NMR spectroscopy . . . . . . . . . . . . . . . 704.3.2 29Si MAS-NMR Spectroscopy . . . . . . . . . . . . . . . 73

5 Poly(siloxonate) and polysilicate, soluble silicate, Si:Al=1:0 795.1 History of soluble silicates . . . . . . . . . . . . . . . . . . . . . . 795.2 Chemical composition of soluble silicates . . . . . . . . . . . . . . 815.3 Manufacture of soluble (Na,K)poly(siloxonate), soluble silicates 82

5.3.1 Chemical mechanism . . . . . . . . . . . . . . . . . . . . 825.3.2 Furnace route . . . . . . . . . . . . . . . . . . . . . . . . 845.3.3 Hydrothermal process . . . . . . . . . . . . . . . . . . . . 875.3.4 Silica fume dissolution . . . . . . . . . . . . . . . . . . . 87

5.4 Structure of solid poly(siloxonate), (Na,K)silicate glasses . . . . 875.4.1 Molecular structure of poly(siloxonate), alkali silicate

glasses . . . . . . . . . . . . . . . . . . . . . . . . . . . . 895.4.2 Molecular structure of poly(siloxonate), alkali-tridymite

glasses . . . . . . . . . . . . . . . . . . . . . . . . . . . . 915.5 Poly(siloxonate) in solution. Hydrolysis, depolymerization of

solid silicates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 975.6 Structure of poly(siloxonate) solutions, soluble alkali silicates . . 98

5.6.1 Early studies . . . . . . . . . . . . . . . . . . . . . . . . 985.6.2 NMR spectroscopy: identification of soluble species . . . 995.6.3 Hydrolysis of poly(siloxonate) alkali-glass into water sol-

uble molecules . . . . . . . . . . . . . . . . . . . . . . . . 101

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5.7 Density, specific gravity . . . . . . . . . . . . . . . . . . . . . . . 1065.8 Viscosity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1075.9 pH value and stability of alkali silicate solutions . . . . . . . . . . 1075.10 Powdered poly(siloxonates), soluble hydrous alkali silicate powders1085.11 Poly(siloxonate) MR=1, Na-metasilicate . . . . . . . . . . . . . . 1095.12 Replacement of poly(siloxonate) solution with powdered equiva-

lent product. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110

6 Chemistry of (Na,K)oligo-sialates: hydrous alumino-silicategels and zeolites 1156.1 Zeolite Synthesis . . . . . . . . . . . . . . . . . . . . . . . . . . . 1156.2 Hypothetical or real oligo-sialates: polymerization mechanism

into poly(sialate) . . . . . . . . . . . . . . . . . . . . . . . . . . . 1186.3 Examples of poly(sialate-multisiloxo) gels . . . . . . . . . . . . . 122

6.3.1 Poly(sialate-disiloxo) gel . . . . . . . . . . . . . . . . . . 1226.3.2 Poly(siloxonate-intra-sialate) gels . . . . . . . . . . . . . 124

7 Kaolinite / Hydrosodalite based geopolymer, poly(sialate) withSi:Al=1:1 1297.1 Geopolymerization mechanism of kaolinite under ionic concept. . 1307.2 Ultra rapid in situ geopolymerization of kaolinite in hydrosoda-

lite, Napoly(sialate). . . . . . . . . . . . . . . . . . . . . . . . . . 1347.3 Geopolymerization mechanism of kaolinite under covalent bond-

ing concept . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1397.4 Hydrosodalite Napoly(sialate) and Zeolite A formation with cal-

cined kaolin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 143

8 Metakaolin MK-750 based geopolymer, poly(sialate-siloxo) withSi:Al=2:1 1498.1 (Na,K)poly(sialate-siloxo) . . . . . . . . . . . . . . . . . . . . . . 1498.2 Alumino-silicate oxide: dehydroxylated kaolinite, MK-750 . . . . 156

8.2.1 Characteristic of kaolinite and dehydroxylated kaolinite . 1578.2.2 IV-fold coordination of Al in dehydroxylated kaolinite,

earlier studies. . . . . . . . . . . . . . . . . . . . . . . . . 1588.2.3 MAS-NMR spectroscopy of dehydroxylated kaolinite . . 1598.2.4 Dehydroxylation mechanism of kaolinite . . . . . . . . . 1638.2.5 Reactivity of MK-750, geopolymerization into (Na,K)

poly(sialate-siloxo) . . . . . . . . . . . . . . . . . . . . . 1678.2.6 Exothermic geopolymerization . . . . . . . . . . . . . . . 1698.2.7 Geopolymerization into poly(sialate-siloxo), a function

of Al(V) content . . . . . . . . . . . . . . . . . . . . . . . 1728.2.8 Geopolymerization of poly(sialate-siloxo), function of SiO2:M2O

MR ratio . . . . . . . . . . . . . . . . . . . . . . . . . . . 1748.2.9 Geopolymerization of poly(sialate-siloxo), function of cur-

ing temperature . . . . . . . . . . . . . . . . . . . . . . . 1758.3 Chemical mechanism: formation of ortho-sialate (OH)3-Si-O-Al-

(OH)3 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1758.3.1 Chemical mechanism with Al(V) -Al=O alumoxyl. . . . 1768.3.2 Chemical mechanism in Al-O-Al-OH geopolymerization . 177

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8.4 Kinetics of chemical attack . . . . . . . . . . . . . . . . . . . . . 1778.5 Chemical mechanism for Na-based sialate: poly(sialate), poly(sialate-

siloxo) and poly(sialate-disiloxo) . . . . . . . . . . . . . . . . . . 1798.5.1 Nepheline framework Si:Al=1, Napoly(sialate) . . . . . 1808.5.2 Albite framework with Q1 di-siloxonate, Si:Al=3, Na

poly(sialate-disiloxo) . . . . . . . . . . . . . . . . . . . . 1818.5.3 Phillipsite framework with Q0 siloxonate, Si:Al=2, Na

poly(sialate-siloxo) . . . . . . . . . . . . . . . . . . . . . 1828.6 Chemical mechanism for K-based sialate: poly(sialate), poly(sialate-

siloxo) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1848.6.1 Kalsilite framework, Si:Al=1, Kpoly(sialate) . . . . . . 1878.6.2 Leucite framework with Q0 siloxonate, Si:Al=2, Kpoly(sialate-

siloxo) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1898.7 Simplified structural model for (Na,K)based geopolymers . . . . 1918.8 Al-O-Al bond formation in geopolymers . . . . . . . . . . . . . . 1948.9 Synthesis of MK-750 type molecules . . . . . . . . . . . . . . . . 196

9 Calcium based geopolymer, (Ca, K, Na)-sialate, Si:Al=1, 2, 3 2019.1 Ca-poly(alumino-sialate), gehlenite hydrate Ca2Al2SiO7, H2O . . 201

9.1.1 Opus Signinum . . . . . . . . . . . . . . . . . . . . . . . 2019.1.2 Ca-poly(alumino-sialate), gehlenite synthesis with MK-

750 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2029.2 (Ca)poly(alumino-sialate) + (Na,K)poly(sialate) . . . . . . . . 2059.3 Ca-poly(alumino-sialate), gehlenite based blast furnace slag . . . 207

9.3.1 The manufacture of iron blast furnace slag glass . . . . . 2089.3.2 Chemical and mineral composition of gehlenite based slag.209

9.4 Alkalination of Ca-poly(alumino-sialate) glassy slag with NaOHand KOH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2119.4.1 Alkalination mechanism study with MAS-NMR spec-

troscopy . . . . . . . . . . . . . . . . . . . . . . . . . . . 2119.4.2 Alkali-Activated slag . . . . . . . . . . . . . . . . . . . . 215

9.5 MK-750 / slag based geopolymer . . . . . . . . . . . . . . . . . . 2169.5.1 Excerpt from Davidovits J. / Sawyer J.L. US Patent

4,509,985, 1985, filed February 22, 1984 . . . . . . . . . . 2169.5.2 Which chemical reaction for MK-750 / slag-based geo-

polymer? . . . . . . . . . . . . . . . . . . . . . . . . . . . 2229.5.3 Formation of soluble calcium disilicate? . . . . . . . . . . 223

9.6 Chemistry mechanism of MK-750 / slag Ca-based geopolymermatrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2319.6.1 MAS-NMR Spectroscopy . . . . . . . . . . . . . . . . . . 2319.6.2 Electron microscopy . . . . . . . . . . . . . . . . . . . . 2349.6.3 Chemistry mechanism, solid solution in Ca-based geo-

polymer matrix . . . . . . . . . . . . . . . . . . . . . . . 2379.6.4 Structural molecular model for Ca-based geopolymer

matrix . . . . . . . . . . . . . . . . . . . . . . . . . . . . 238

10 Rock-based geopolymer, poly(sialate-multisiloxo) 1

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10.1.2 Incongruent dissolution and covalent bonding concept . . 24710.2 (Na,K)poly(sialate) matrix for rock based geopolymerization . . 25010.3 (K,Ca)poly(sialate-multisiloxo) matrix for rock-based geopoly-

mers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 254

11 Silica-based geopolymer, sialate link and siloxo link in poly(siloxonate)Si:Al>5 26311.1 A 5000 year-old technique . . . . . . . . . . . . . . . . . . . . . . 26311.2 Silica Flour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26711.3 Nano-silica, micro-silica, silica fume SiO2 . . . . . . . . . . . . . . 267

11.3.1 Fume silica SiO2 . . . . . . . . . . . . . . . . . . . . . . 26811.3.2 Silica Fume / Microsilica . . . . . . . . . . . . . . . . . . 268

11.4 Rice Husk Ash . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27011.5 Applications of SiO2 nano-particles and rice husk ash . . . . . . . 27111.6 Poly(siloxo) and poly(sialate) cross-links, nanocomposite geopo-

lymer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27211.6.1 Nano-poly(siloxo) geopolymer . . . . . . . . . . . . . . . 27311.6.2 29Si MAS-NMR studies on the transition nano-poly(silanol)

to nano-poly(siloxo) . . . . . . . . . . . . . . . . . . . . . 27411.6.3 1H MAS-NMR studies . . . . . . . . . . . . . . . . . . . 27511.6.4 Knanopoly(sialate) geopolymer composite . . . . . . . 278

11.7 Possible health hazards of SiO2 nanoparticles . . . . . . . . . . . 280

12 Fly ash-based geopolymer 28312.1 Production of fly ashes . . . . . . . . . . . . . . . . . . . . . . . . 284

12.1.1 Types of fly ash, composition . . . . . . . . . . . . . . . 28512.1.2 Morphology . . . . . . . . . . . . . . . . . . . . . . . . . 287

12.2 Alkalination, dissolution and zeolite formation . . . . . . . . . . . 28712.3 Geopolymerization in high alkaline milieu (corrosive system) . . . 289

12.3.1 First production of fly ash-based cement . . . . . . . . . 28912.3.2 Fly ash geopolymerization without soluble silicate? . . . 29212.3.3 Fly ash geopolymerization with addition of soluble silicate.294

12.4 Geopolymerization in low alkaline milieu (user-friendly) . . . . . 29612.4.1 NMR spectroscopy . . . . . . . . . . . . . . . . . . . . . 297

12.5 The GEOASH research project . . . . . . . . . . . . . . . . . . . 29912.5.1 Alkali-activation and geopolymerization . . . . . . . . . 30212.5.2 Compressive strength . . . . . . . . . . . . . . . . . . . . 30312.5.3 X-ray diraction . . . . . . . . . . . . . . . . . . . . . . 30712.5.4 Leaching properties . . . . . . . . . . . . . . . . . . . . . 30912.5.5 (Ca,K)-based geopolymer matrix: composition and struc-

ture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30912.6 The future with gasifier slag technology . . . . . . . . . . . . . . 311

13 Phosphate-based geopolymers 31513.1 A 4500 year-old Egyptian technology! . . . . . . . . . . . . . . . 31513.2 Brief survey of phosphate chemistry . . . . . . . . . . . . . . . . 317

13.2.1 Ortho-, di-, tri- and poly-phosphoric acid . . . . . . . . . 31713.2.2 Polyphosphate linear chains . . . . . . . . . . . . . . . . 318

13.3 Low-molecular phosphate-based geopolymers . . . . . . . . . . . 320

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13.4 Poly(sialate-siloxo) / phosphate composites . . . . . . . . . . . . 32113.5 Phospho-siloxonate geopolymer, -Si-O-P-O-Si- . . . . . . . . . . . 322

13.5.1 Ca-phospho-silicate . . . . . . . . . . . . . . . . . . . . . 32413.6 AlPO4-based geopolymers . . . . . . . . . . . . . . . . . . . . . . 328

13.6.1 Polymeric structures of AlPO4-geopolymers: 27Al and31P NMR. . . . . . . . . . . . . . . . . . . . . . . . . . . 329

13.6.2 Synthesis of AlPO4-geopolymers: the solution and sol-gel routes . . . . . . . . . . . . . . . . . . . . . . . . . . 330

13.6.3 Synthesis of AlPO4-geopolymers: the modified Al2O3routes . . . . . . . . . . . . . . . . . . . . . . . . . . . . 332

13.6.4 MK-750 metakaolin-based AlPO4-geopolymer . . . . . . 333

14 Organic-mineral geopolymer 33714.1 Poly-organo-siloxanes / silicones . . . . . . . . . . . . . . . . . . . 337

14.1.1 Geopolymeric identity . . . . . . . . . . . . . . . . . . . 33714.1.2 Two polymerization mechanisms: acidic and basic . . . . 33814.1.3 Depolymerization and cleavage . . . . . . . . . . . . . . 34014.1.4 Properties of technical silicones . . . . . . . . . . . . . . 340

14.2 Kerogen-geopolymer . . . . . . . . . . . . . . . . . . . . . . . . . 34314.3 Organo-geopolymer compounds . . . . . . . . . . . . . . . . . . . 345

14.3.1 Inclusion of hydrophilic polymers, poly(ethylene glycol) . 34614.3.2 Reaction with isocyanate R-N=C=O . . . . . . . . . . . 34714.3.3 Reaction with poly(acrylic acid) R-C(=O)-OH . . . . . . 34814.3.4 Reaction with aqueous phenolic resin and poly(styrene

butadiene) latex . . . . . . . . . . . . . . . . . . . . . . 348

III Properties 353

15 Physical properties of condensed geopolymers 35515.1 Density and softening temperature . . . . . . . . . . . . . . . . . 35515.2 Thermal behavior, shrinkage on dehydroxylation . . . . . . . . . 356

15.2.1 DTA-TGA and Shrinkage on dehydration and dehydrox-ylation . . . . . . . . . . . . . . . . . . . . . . . . . . . . 356

15.2.2 Yield of the conversion of kaolinite into Napoly(sialate)NaPS . . . . . . . . . . . . . . . . . . . . . . . . . . . . 359

15.3 Thermal Expansion C.T.E. . . . . . . . . . . . . . . . . . . . . . 36015.3.1 C.T.E. Coecient of Thermal Expansion . . . . . . . . . 36115.3.2 Mean linear thermal expansion, the major role of ce-

ramic fillers . . . . . . . . . . . . . . . . . . . . . . . . . 36215.4 Water and moisture absorption . . . . . . . . . . . . . . . . . . . 36415.5 Electrical values: resistivity and dielectric properties . . . . . . . 36615.6 Adhesion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 368

15.6.1 Adhesion on natural stone; geopolymer with Si:Al=2 . . 36815.6.2 Adhesion on steel and glass, Geopolymer with Si:Al=2 . 36815.6.3 Adhesion on metal, Geopolymer with Si:Al>20 . . . . . 370

15.7 Practical physical properties . . . . . . . . . . . . . . . . . . . . . 371

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16 Chemical Properties of condensed geopolymers 37516.1 Acid resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . 377

16.1.1 Influence of acid on incompletely condensed Napoly(sialate-siloxo) . . . . . . . . . . . . . . . . . . . . . . . . . . . . 378

16.1.2 Acid resistance of geopolymer cement towards sulfuricacid . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380

16.1.3 Sulfate resistance of geopolymer cement . . . . . . . . . 38316.2 Alkali-aggregate reaction . . . . . . . . . . . . . . . . . . . . . . . 38316.3 Corrosion of metal bars . . . . . . . . . . . . . . . . . . . . . . . 38516.4 Practical chemical properties . . . . . . . . . . . . . . . . . . . . 386

16.4.1 pH values . . . . . . . . . . . . . . . . . . . . . . . . . . 38616.4.2 (K,Ca)poly(sialate-siloxo) and (K,Ca)poly(sialate-disiloxo)

cements: . . . . . . . . . . . . . . . . . . . . . . . . . . . 386

17 Long-term durability, archaeological analogues, geological ana-logues 38917.1 The oldest geopolymer artifact: 25000 year-old ceramic Venus

from Doln Vstonice . . . . . . . . . . . . . . . . . . . . . . . . . 39017.2 Chemicals extracted from plant ashes . . . . . . . . . . . . . . . . 39117.3 Egyptian Pyramid stone, re-agglomerated limestone concrete,

2700 B.C. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39217.3.1 Chemistry of the core blocks . . . . . . . . . . . . . . . . 39517.3.2 Chemistry of the casing stones . . . . . . . . . . . . . . . 39617.3.3 The experimentation: manufacturing 14 tonnes of pyra-

mid stones . . . . . . . . . . . . . . . . . . . . . . . . . . 39717.4 Ancient Roman cements and concretes . . . . . . . . . . . . . . . 398

17.4.1 Cements and concretes . . . . . . . . . . . . . . . . . . . 39917.4.2 The second high-performance Roman cement, with Car-

bunculus. . . . . . . . . . . . . . . . . . . . . . . . . . . 40017.4.3 Comparison between Roman and modern geopolymer

cements . . . . . . . . . . . . . . . . . . . . . . . . . . . 40117.5 Geological analogues . . . . . . . . . . . . . . . . . . . . . . . . . 406

IVApplications 409

18 Quality control 41318.1 Raw-materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 413

18.1.1 Solid elemental composition . . . . . . . . . . . . . . . . 41318.1.2 pH determination of the raw-materials . . . . . . . . . . 41518.1.3 Granulometry . . . . . . . . . . . . . . . . . . . . . . . . 417

18.2 Determination of the geopolymeric reactivity . . . . . . . . . . . 41818.3 Working time (pot-life), resin and paste . . . . . . . . . . . . . . 420

18.3.1 Working time (pot-life) . . . . . . . . . . . . . . . . . . . 42018.3.2 Role of additional water . . . . . . . . . . . . . . . . . . 42118.3.3 Control on the hardening paste: penetrometer . . . . . . 42318.3.4 Plasticizers and retarders . . . . . . . . . . . . . . . . . . 424

18.4 Compressive strength and tensile strength . . . . . . . . . . . . . 425

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Contents

18.4.1 Compressive strength . . . . . . . . . . . . . . . . . . . . 42518.4.2 Tensile strength . . . . . . . . . . . . . . . . . . . . . . . 427

18.5 Additional fast testing on hardened geopolymers . . . . . . . . . 42818.5.1 Boiling water / steam . . . . . . . . . . . . . . . . . . . . 42818.5.2 Freeze-Thaw / Wet-Dry . . . . . . . . . . . . . . . . . . 42818.5.3 Thermal behavior, expansion at 250C, thermal dilatom-

etry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 429

19 Development of user-friendly systems 43319.1 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43319.2 The need for user-friendly systems . . . . . . . . . . . . . . . . . 43419.3 The position of civil engineers . . . . . . . . . . . . . . . . . . . . 43719.4 The pH values of geopolymers . . . . . . . . . . . . . . . . . . . . 43819.5 K+ versus Na+ . . . . . . . . . . . . . . . . . . . . . . . . . . . . 440

20 Castable geopolymer, industrial and decorative applications 44520.1 The 5000 year-old Egyptian stone vases . . . . . . . . . . . . . . 44520.2 Kpoly(sialate-siloxo) for castable artifacts. . . . . . . . . . . . . 44920.3 Tooling materials and techniques . . . . . . . . . . . . . . . . . . 454

20.3.1 Advanced geopolymer tooling . . . . . . . . . . . . . . . 45420.3.2 Instruction for use . . . . . . . . . . . . . . . . . . . . . 455

20.4 Modern geopolymer stone artifacts . . . . . . . . . . . . . . . . . 45820.5 Decorative stone tiles for floor and wall . . . . . . . . . . . . . . . 45920.6 Restoration of ceramic works of art . . . . . . . . . . . . . . . . . 460

21 Geopolymer fiber composites 46321.1 Fundamental remarks on heat and fire resistance . . . . . . . . . 464

21.1.1 Heat resistance applications in racing cars . . . . . . . . 46421.1.2 Review of carbon/geopolymer and other ceramic-ceramic

composites . . . . . . . . . . . . . . . . . . . . . . . . . . 46621.2 The development of high performance geopolymer matrices . . . 468

21.2.1 Kpoly(sialate) KPS/KPSS matrix . . . . . . . . . . . 46821.2.2 Improvement of the matrices: KPSDS, F,M-PSDS and

KnanoPSS . . . . . . . . . . . . . . . . . . . . . . . . . 47121.2.3 Improvement with high-temperature post-treatment of

the matrices KPS / KPSS . . . . . . . . . . . . . . . . 47321.3 Principles in geopolymer-composite manufacture . . . . . . . . . 474

21.3.1 Hand lay-up . . . . . . . . . . . . . . . . . . . . . . . . . 47521.3.2 Vacuum bagging . . . . . . . . . . . . . . . . . . . . . . 47521.3.3 Filament winding . . . . . . . . . . . . . . . . . . . . . . 47621.3.4 Resin Transfer Molding, RTM (injection molding) . . . . 47621.3.5 Infusion (infiltration) process . . . . . . . . . . . . . . . 47721.3.6 Autoclave curing . . . . . . . . . . . . . . . . . . . . . . 477

21.4 Geopolymer-composite tools fabrication . . . . . . . . . . . . . . 47821.5 Fire resistance with Knanopoly(sialate) laminates . . . . . . . 481

21.5.1 Fabrication of Knanopoly(sialate) carbon compositefor fire-resistance testing . . . . . . . . . . . . . . . . . . 481

21.5.2 Flammability of organic and geopolymer composites . . 48321.5.3 Flashover temperature . . . . . . . . . . . . . . . . . . . 484

viii

Contents

21.5.4 Residual strength after fire exposure . . . . . . . . . . . 48521.6 Fatigue loading of Knanopoly(sialate) / carbon composite . . . 48621.7 Knanopoly(sialate) / carbon / E-glass composite . . . . . . . 48721.8 Geopolymer composite sandwiches for heat barrier . . . . . . . . 48821.9 Geopolymer composite for strengthening concrete structures . . . 48921.10 Geopolymer composite for fire resistant structural elements . . . 491

22 Foamed geopolymer 49722.1 Geopolymer foam fabrication . . . . . . . . . . . . . . . . . . . . 498

22.1.1 Foaming with Na perborate . . . . . . . . . . . . . . . . 49822.1.2 Foaming with H2O2 . . . . . . . . . . . . . . . . . . . . . 49922.1.3 Insulating value of geopolymer foam . . . . . . . . . . . 500

22.2 High-temperature insulation . . . . . . . . . . . . . . . . . . . . . 50122.3 Passive cooling of buildings in hot / arid climate . . . . . . . . . 50222.4 Passive Cooling in big cities . . . . . . . . . . . . . . . . . . . . . 504

23 Geopolymers in ceramic processing 50723.1 Low Temperature Geopolymeric Setting of ceramic, LTGS . . . . 507

23.1.1 Geopolymeric setting at room temperature below 65C . 50823.1.2 Geopolymeric setting at temperatures ranging between

80C and 450C . . . . . . . . . . . . . . . . . . . . . . . 51023.1.3 Resistance to water . . . . . . . . . . . . . . . . . . . . . 510

23.2 Archaeological ceramics . . . . . . . . . . . . . . . . . . . . . . . 51023.2.1 Evidence of LTGS in ancient ceramics . . . . . . . . . . 51123.2.2 The making of Etruscan Ceramic (Bucchero Nero) in

600700 B.C. . . . . . . . . . . . . . . . . . . . . . . . . 51223.2.3 The making of Ceramic with black or brown-black finish

in a wood campfire, at temperature lower than 500C . . 51523.2.4 User-friendly LTGS . . . . . . . . . . . . . . . . . . . . . 518

23.3 Low-energy modern ceramic processing and sustainable develop-ment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 518

23.4 The making of foamed clay bricks . . . . . . . . . . . . . . . . . . 52223.5 Ceramics with no clay? . . . . . . . . . . . . . . . . . . . . . . . . 52323.6 The geopolymer route to high-temperature ceramics . . . . . . . 524

23.6.1 High-tech Leucite and Kalsilite from geopolymer pre-cursors . . . . . . . . . . . . . . . . . . . . . . . . . . . . 524

23.6.2 High-tech Pollucite, -Spodumene, Liebenbergite fromgeopolymer precursors . . . . . . . . . . . . . . . . . . . 526

23.6.3 Gallium-, Germanium-based geopolymers . . . . . . . . . 528

24 The manufacture of geopolymer cements 53324.1 Greenhouse CO2 mitigation fosters the development of geopoly-

mer cements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53424.1.1 Cement CO2 emissions in developing countries . . . . . . 53524.1.2 Comparison between CaO, Na2O and K2O cementitious

systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53724.1.3 Examples of low-CO2 mitigation with geopolymer cements53924.1.4 Geopolymer cement for CO2 storage and sequestration . 540

24.2 Additional Raw-Materials from industrial wastes . . . . . . . . . 542

ix

Contents

24.2.1 Muscovite based mine tailings . . . . . . . . . . . . . . . 54224.2.2 Kaolinitic shale wastes . . . . . . . . . . . . . . . . . . . 54224.2.3 Coal-waste mine tailings . . . . . . . . . . . . . . . . . . 54224.2.4 Coal honeycomb briquette ash . . . . . . . . . . . . . . . 54424.2.5 Public water reservoir sludge . . . . . . . . . . . . . . . . 54524.2.6 Ferronickel slag . . . . . . . . . . . . . . . . . . . . . . . 545

24.3 The need for dry mix geopolymer cement . . . . . . . . . . . . . 54624.3.1 The use of solid silica + solid alkalis . . . . . . . . . . . 54624.3.2 Manufacture of powdered K-silicate with MR SiO2:K2O

< 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54724.3.3 Not realistic for mass production of geopolymer cements 548

24.4 Replacement of (Na,K) soluble silicates with synthetic lavas . . . 54924.4.1 The manufacture of synthetic lavas . . . . . . . . . . . . 54924.4.2 Molecular structure of synthetic lava . . . . . . . . . . . 55224.4.3 The molecular structure of lava-based geopolymer cement55424.4.4 Geopolymer cement mass production with synthetic lava?556

25 Geopolymer concrete 56125.1 Mixture proportions of fly ash-based geopolymer concrete . . . . 56125.2 Mixing, casting, and compaction of fly ash-based geopolymer

concrete . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56325.3 Curing of fly ash-based geopolymer concrete . . . . . . . . . . . . 56425.4 Design of fly ash-based geopolymer concrete mixtures . . . . . . . 56625.5 Short-term properties of fly ash-based geopolymer concrete . . . 568

25.5.1 Behavior in compression . . . . . . . . . . . . . . . . . . 56825.5.2 Compressive strength of aggregates weaker than geopo-

lymer matrix . . . . . . . . . . . . . . . . . . . . . . . . 56925.5.3 Indirect tensile strength . . . . . . . . . . . . . . . . . . 57025.5.4 Unit-weight . . . . . . . . . . . . . . . . . . . . . . . . . 571

25.6 Long-term properties of fly ash-based geopolymer concrete . . . 57125.6.1 Compressive strength . . . . . . . . . . . . . . . . . . . . 57125.6.2 Creep and drying shrinkage . . . . . . . . . . . . . . . . 573

25.7 Reinforced geopolymer concrete beams and columns . . . . . . . 57625.8 Better than Portland cement concrete? . . . . . . . . . . . . . . 581

26 Geopolymers in toxic waste management 58526.1 Containment with barriers . . . . . . . . . . . . . . . . . . . . . . 58826.2 Waste encapsulation requires MK-750-based geopolymers . . . . 589

26.2.1 Structural model for safe encapsulation . . . . . . . . . . 58926.2.2 Safe chemical bonding with MK-750-based geopolymers 590

26.3 Heavy metals in mine tailings . . . . . . . . . . . . . . . . . . . . 59126.3.1 Solidification procedure . . . . . . . . . . . . . . . . . . 59226.3.2 Leachate testing . . . . . . . . . . . . . . . . . . . . . . . 592

26.4 The use of geopolymers for paint sludge disposal . . . . . . . . . 59526.4.1 Experimental . . . . . . . . . . . . . . . . . . . . . . . . 59526.4.2 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . 596

26.5 Treatment of arsenic-bearing wastes . . . . . . . . . . . . . . . . 59726.5.1 Nature of the Problem . . . . . . . . . . . . . . . . . . . 59726.5.2 Geopolymeric Solidification . . . . . . . . . . . . . . . . 598

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Contents

26.6 Uranium mining waste treatment . . . . . . . . . . . . . . . . . . 60026.6.1 Specificity of uranium immobilization . . . . . . . . . . . 60126.6.2 The uranium waste sludge . . . . . . . . . . . . . . . . . 60226.6.3 Two-Step solidification technology . . . . . . . . . . . . . 60326.6.4 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60326.6.5 Pilot-scale experimentation . . . . . . . . . . . . . . . . 606

26.7 Geopolymers in other toxic-radioactive waste management ap-plications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 608

xi

Part I

Polymers and Geopolymers

1

Chapter 1

Introduction

The discovery of a new class of inorganic materials, geopolymerresins, binders, cements and concretes, resulted in wide scientific in-terest and kaleidoscopic development of applications. From the firstindustrial research eorts in 1972 at the Cordi-Gopolymre privateresearch laboratory, Saint-Quentin, France, until the end of 2006,hundreds of papers and patents were published dealing with geopo-lymer science and technology. On August 31. 2005, the GeopolymerInstitute (a non-profit scientific organization founded in 1979) wasproud to announce in its News on line (www.geopolymer.org): "Since1997, 80000 papers have been downloaded by 15000 scientists aroundthe world at the geopolymer.org website". The extent of internationalscientific and commercial interest in geopolymers was evidenced byseveral large conferences. In France, the First European Confer-ence on Soft Mineralurgy, organized by the Geopolymer Instituteand sponsored by the European Economic Commission, was held atthe University of Technology of Compigne in June 1988 (Geopoly-mer 88 ). Eleven years later in June-July 1999, the Geopolymer In-stitute organized the Second International Conference Geopolymere99, held in Saint-Quentin; the published proceedings included 32papers presented to the 100 scientists from over 12 countries. TheThird International Conference, Geopolymer 2002 was held in Aus-tralia in October 2002. Organized by the University of Melbourneand chaired by J.S.J. van Deventer, it focused on the ways needed to"Turn Potential into Profit".

Since 2003, several national and international scientific institu-tions have organized "geopolymer sessions", "geopolymer seminars"

3

1. Introduction

and "geopolymer conferences". The Geopolymer 2005World Congresswas a tribute to the 26th anniversary of the creation of the Geopoly-mer Institute by J. Davidovits. The main topic of the world congresswas Geopolymer-chemistry and sustainable Development. It gatheredtwo major events in two dierent locations: the Fourth InternationalConference in Saint-Quentin, France, June-July, 2005, organized bythe Geopolymer Institute; the International Workshop on Geopo-lymer Cements and Concrete in Perth, Australia, September 2005,chaired by V.J. Rangan, organized by Curtin University of Tech-nology, Perth, the University of Alabama, USA, and sponsored bythe National Science Foundation, USA. The conference and work-shop covered the science and application of geopolymers. More than200 scientists attended the congress and 85 international public andprivate research institutions presented a total of 75 papers. Theycover a wide scope of topics ranging from geopolymer chemistry, in-dustrial wastes and raw materials, geopolymer cements, geopolymerconcretes (including fly ash-based geopolymers), applications in con-struction materials, applications in high-tech materials, matrix forfire/heat resistant composites, and applications in archaeology. Thepublished proceedings (Geopolymer 2005 ) includes 60 selected pa-pers and is titled: Geopolymer, Green Chemistry and SustainableDevelopment Solutions. In 2009, we agreed to propose every yeartwo international events: a Geopolymer Symposium in January, atDaytona Beach, Florida, USA, with the frame of the InternationalConference on Advanced Ceramics and Composites, organized bythe American Ceramic Society, and a Geopolymer Camp in July, atSaint-Quentin, France, organized by the Geopolymer Institute.

1.1 Geopolymer technology

How should we consider geopolymers? Are they a new material,a new binder or a new cement for concrete? Geopolymers are allof these. They are new materials for coatings and adhesives, newbinders for fiber composites, waste encapsulation and new cementfor concrete. The properties and uses of geopolymers are being ex-plored in many scientific and industrial disciplines: modern inor-ganic chemistry, physical chemistry, colloid chemistry, mineralogy,geology, and in all types of engineering process technologies. Thewide variety of potential applications includes: fire resistant materi-

4

Geopolymer technology

als, decorative stone artifacts, thermal insulation, low-tech buildingmaterials, low energy ceramic tiles, refractory items, thermal shockrefractories, bio-technologies (materials for medicinal applications),foundry industry, cements and concretes, composites for infrastruc-tures repair and strengthening, high-tech composites for aircraft in-terior and automobile, high-tech resin systems, radioactive and toxicwaste containment, arts and decoration, cultural heritage, archaeol-ogy and history of sciences.

My chemistry background had focused on organic polymer chem-istry and in the aftermath of various catastrophic fires in Francebetween 197072, which involved common organic plastic, researchon nonflammable and noncombustible plastic materials became myobjective. In 1972, I founded the private research company CordiSA, later called Cordi-Gopolymre. In my pursuit to develop newinorganic polymer materials, I was struck by the fact that the samesimple hydrothermal conditions governed the synthesis of some or-ganic plastics in alkali medium, as well as mineral feldspathoids andzeolites.

Thus, phenol and formaldehyde polycondense into the famousBakelite invented by Bakeland at the beginning of the 20th Century,one of the oldest man-made plastic (Figure 1.1).

Figure 1.1: Phenoplast polycondensation between phenol and formaldehyde, in alkalimedium.

On the other hand, the aluminosilicate kaolinite reacts with NaOHat 100150C and polycondenses into hydrated sodalite (a tectoalu-minosilicate, a feldspathoid), or hydroxysodalite (Figure 1.3).

From the study of the scientific and patent literature covering thesynthesis of zeolites and molecular sieves essentially in the form

5

1. Introduction

Figure 1.2: Polycondensation of kaolinite Si2O5,Al2(OH)4 in alkali medium.

of powders it became clear that this geochemistry had so far notbeen investigated for producing mineral binders and mineral poly-mers. I proceeded therefore to develop amorphous to semi-crystallinethree-dimensional silico-aluminate materials, which I call in French"gopolymres", geopolymers (mineral polymers resulting from geo-chemistry or geosynthesis).

The first applications were building products developed in 19731976, such as fire-resistant chip-board panels, comprised of a woodencore faced with two geopolymer nanocomposite coatings, in whichthe entire panel was manufactured in a one-step process (Davidovits,1973). We coined it "Siliface Process". An unusual feature was ob-served to characterize the manufacturing process: for the first time,the hardening of organic material (wood chips and organic resin basedon urea-formaldehyde aminoplast) occurred simultaneously with thesetting of the mineral silico-aluminate (Napoly(sialate) / quartznanocomposite), when applying the same thermosetting parametersas for organic resin: 150180C temperature (Davidovits, 1976).

1.1.1 The invention of the first mineral resin,October 1975

Since 1972, we were involved in applying a methodology based onthe transformation of kaolinitic clays. The material was wet clay andcould only be processed through compression or extrusion. We didnot have at our disposal a fluid binder, so far. The real breakthroughtook place when, in 1975, we discovered at the CORDI laboratorya geopolymeric liquid binder based on metakaolin and soluble alkalisilicate. I recognized the potential of this discovery and presented anEnveloppe Soleau for registration at the French Patent Oce. Hereis the English translation of the hand written text:

6

Geopolymer technology

Figure 1.3: Enveloppe Soleau filed on 29/12/1975

Text of the Enveloppe Soleau filed on 29/12/1975, number 70528,at Institut National de la Proprit Industrielle, INPI, Paris. Englishtranslation from French:

"Since October 1, 1975 we study the behaviour of metakaolin inour Siliface system. The first goal was to find a process for the man-ufacture of synthetic zeolites (type Zeolite A) by reacting metakaolin+ NaOH. We noticed that this mixture was prone to a very impor-tant exothermic reaction [t exceeding 100C after 1 hour of storagein a bag]. If we do not let this exothermic reaction to start at roomtemperature, namely if we cure immediately the mixture, then theexothermic reaction becomes very powerful and the product obtainedis very hard after 2 minutes at 120C; X-ray diraction shows picksattributed to hydrosodalite and to Zeolite A. We immediately planedto use this exothermic reaction in the manufacturing of insulatingblocks consisting entirely of a mineral core made of expanded shaleor expanded glass spheres, agglomerated with metakaolin + NaOH.In a panel covered with a Siliface facing, the temperature in the cen-ter of a 15 cm thick core reaches 100C after only 3-4 minutes. Theaddition of a binder such as Na-Silicate leads to a liquid coating, andallows reducing the quantity of mineral binder used in the process.

7

1. Introduction

It seems that metakaolin behaves as a hardener for Na-Silicate.Consequently, a mixture involving Na-Silicate + NaOH + Meta-

kaolin has the following advantages:- Exothermicity (hardening to the heart of thick material);- Reaction with Na-Silicate (very fast hardening of the liquid

binder).Tests already undertaken on: - zeolites; - agglomeration of wood

chips (A2 panels); - sand agglomeration (foundry cores); - mineraland refractory fire barrier.

Another consequence of this discovery is that one can treat com-mon clays at 500-600C, to obtain a very reactive argillaceous rawmaterial (metakaolin type) being able to be used in the precedingexamples in place of pure metakaolin, together with Na-Silicate, oralone. This opens very interesting new prospects. It is a step towardsmore knowledge on the specific reactions involving mineral polymers,either by using natural raw materials for example standard clay likeClrac B16, dried, ground, or by performing the suitable treatmentto transform them into reactive raw material. New patent filings willsanction all these discoveries. On December 20, 1975, J. Davidovits"End of translation.

It was the first mineral resin ever manufactured. The title of thepatent, Mineral polymer, was self evident (Davidovits, 1979). Thecommercial product, coined Geopolymite, was a good fire resistantalternative to organic resin. Then, Neuscher (1983) at the licensedGerman Company Dynamit Nobel (later Hls Troisdorf AG) discov-ered the high reactivity of silica and alumina fumes, by-products ofthe manufacture of high-tech ceramics.

In early 1983, the Chairman of Lone Star Industries Inc., at thistime the leading cement manufacturer on the American continent,was traveling in Europe and learned about our new geopolymericbinders. Lone Star Industries and Shell Oil Company had just an-nounced the formation of a corporation to develop, produce, and mar-ket a new class of materials that were expected to have a wide-rangingimpact on construction, architectural, and engineering applications.These materials were made from mineral aggregates combined withorganic polymers and monomers. In other words, it was an "organicpolymer concrete". Shell Oil supplied the chemical expertise in or-ganic polymers, while Lone Star supplied the mineral aggregates. Byenlisting our new inorganic geopolymers, Lone Star took the oppor-tunity to challenge Shell Oils chemical expertise. In August 1983,

8

Geopolymer technology

with James Sawyer as Head of Lone Stars research laboratory inHouston, Texas, I started to develop early high-strength geopolyme-ric binders and cements based on both geopolymeric and hydrauliccement chemistries. Within one month, Lone Star Industries Inc.formed the development company, Pyrament, which was exclusivelydedicated to the implementation of this new class of cement. A fewmonths later, Lone Star separated from the Shell Oil deal. It wasdiscovered that the addition of ground blast furnace slag, which isa latent hydraulic cementitious product, to the poly(sialate) type ofgeopolymer, accelerates the setting time and significantly improvescompressive and flexural strength. The first Davidovits and Sawyer(1985) patent was filed in Feb. 22, 1984, and titled "Early High-Strength Mineral Polymer" (US Patent). The corresponding Euro-pean Patent, filed in 1985, is titled "Early High-Strength ConcreteComposition" and these patents disclose our preliminary finding fromthe research carried out in August-September of 1983. Geopolymercements are acid-resistant cementitious materials with zeolitic prop-erties that can be applied to the long-term containment of hazardousand toxic wastes.

At Lone Star, in 1984, Richard Heitzmann and James Sawyerlikewise blended Portland cement with geopolymer. Their purposewas to take advantage of the good properties of geopolymeric cementalong with the low manufacturing cost of Portland cement. The re-sulting PyramentBlended Cement (PBC) was very close to alkali-activated pozzolanic cement. It comprised 80 % ordinary Portlandcement and 20 % of geopolymeric raw materials (Heitzmann et al.,1989). Pyrament PBC was recognized in the construction industryfor its ability to gain very high early strength quite rapidly (US ArmyCorps of Engineers, 1985). It was the ideal material for repairing run-ways made of concrete, industrial pavements, and highway roads. Inthe case of a runway, a 46 hours hardening is enough to allow thelanding of an Airbus or a Boeing. The geopolymeric cement reaches acompression strength of 20 MPa after 4 hours, whereas plain concretegets to this strength after several days. As of fall 1993, Pyramentconcrete was listed for over 50 industrial facilities and 57 militaryinstallations in the USA, and 7 in other countries, and for nonmil-itary airports. In 1994 the US Army Corps of Engineers released awell-documented study on the properties of Pyrament Blended Ce-ments based concretes, which are performing better than had everbeen expected for high-quality concretes.

9

1. Introduction

In the field of so-called high-tech applications, since 1982, theFrench aeronautic company Dassault Aviation (Vautey, 1990) hasused geopolymer molds and tooling in the development of FrenchAirforce fighters (Davidovits et al. 1991). More than a hundred tool-ing and other items have been delivered for aeronautic applicationsand SPF Aluminum processing. In 1994 the American Federal Avi-ation Administration (FAA) with R. Lyon, initiated a cooperativeresearch program to develop environmentally friendly, fire resistantmatrix materials for aircraft composites and cabin interior applica-tions. The Geopolymer composites were selected by FAA as the bestcandidate for this program (Lyon, 1997).

Environmentally-driven geopolymer applications are based on theimplementation of (K,Ca)poly(sialate-siloxo) / (K,Ca)poly(sialate-disiloxo) cements. In industrialized countries (Western countries)emphasis is put on toxic waste (heavy metals) and radioactive wastesafe containment. On the other hand, in emerging countries, theapplications relate to sustainable development, essentially geopoly-meric cements with very low CO2 emission. Both fields of applicationare strongly dependent on politically driven decisions. Heavy metalwaste encapsulation with geopolymer started in 1987, in Canada,with the financial support of CANMET Ottawa, Ontario ResearchFoundation, Toronto, and Comrie Consulting (Davidovits and Com-rie, 1988). The safe containment of uranium mine tailings and ra-dioactive sludge started in 1994 within the European research projectGEOCISTEM, funded by the European Union. The GEOCISTEMproject was aimed at manufacturing cost-eectively new geopoly-meric cements (Geocistem, 1997). It was experimented on two im-portant uranium-mining locations of Wismut, former East Germany,with the collaboration of BPS Engineering, Germany. Our resultsclearly show that solidification with geopolymeric cement (K,Ca)poly(sialate-siloxo) is a prime candidate to cost-eciently fill the gapbetween conventional concrete technology and vitrification methods(Hermann et al., 1999).

Major eorts were dedicated to greenhouse CO2 mitigation withthe development of low CO2 geopolymer cements. My research onthis very important geopolymer application started in 1990 at Penn-State University, Materials Research Laboratory, USA. The produc-tion of 1 tonne of kaolin based-geopolymeric cement generates 0.180tonnes of CO2, from combustion carbon-fuel, compared with 1 tonneof CO2 for Portland cement, i.e. six times less. Fly ash based-

10

The scope of the book

geopolymeric cement has attracted intensive research world-wide be-cause it emits even less CO2, up to nine times less than Portlandcement. This simply means that, in newly industrializing countries,six to nine times more cement for infrastructure and building appli-cations might be manufactured, for the same emission of green housegas CO2 (Davidovits, 1993). One particular project, GEOASH, dealtwith the study of European fly ashes and the implementation of user-friendly processes (GEOASH, 2004-2007).

1.2 The scope of the book

Although review articles and conference proceedings cover variousaspects of the science and application of geopolymers, a researcheror engineer is still at a loss to readily obtain specific informationabout geopolymers and their use. It is this void that we hope to fillwith this book.

There are two main purposes in preparing this book: it is anintroduction to the subject of geopolymers for the newcomer to thefield, for students, and a reference for additional information. Back-ground details on structure, properties, characterization, synthesis,chemistry applications are included.

Each chapter is followed by a bibliography of the relevant pub-lished literature including patents. There are many examples in geo-polymer science where an issued patent is either a primary referenceor the only source of essential technical information. Excerpts fromthe more important patents are included in some chapters.

The industrial applications of geopolymers with engineering pro-cedures and design of processes is also covered in this book.

1.3 Early observations

In the 1930s, alkalis, such as sodium and potassium hydroxide, wereoriginally used to test iron blast furnace ground slag to determine ifthe slag would set when added to Portland cement. In the course ofstudying the testing systems for slag, Belgian scientist Purdon (1940)discovered that the alkali addition produced a new, rapid-hardeningbinder (see Table 1.1). Alkali-activated slag cements (called Triefcements) were used in large-scale construction as early as the 1950s.The usual activation called for adding 1.5 % NaCl and 1.5 % NaOH to

11

1. Introduction

97 % ground slag mix (U.S. Army Engineer Waterways ExperimentStation, 1953). In 1957, Victor Glukhovsky, a scientist working inthe Ukraine at the KICE (Kiev Institute of Civil Engineering in theUSSR) investigated the problem of alkali-activated slag binders andin the 1960s and 1970s made major contribution in identifying bothcalcium silicate hydrates, and calcium and sodium alumino-silicatehydrates (zeolites) as solidification products. He also noted thatrocks and clay minerals react during alkali treatment to form sodiumalumino-silicate hydrates (zeolites), confirming earlier work carriedout on clay reactivity (see below). Glukhovsky called the concretesproduced with this technology "soil silicate concretes" (1959) and thebinders "soil cements" (1967).

Table 1.1: Milestones in alumino-silicate chemistry.

Zeolite molecular Alkali-activation Hydrosodalite Geopolymersieve (slag) (kaolin)

1930 1934 : Olsen(Netherland)

1940 1940 : Purdon 1945 : US Bureau(Belgium) of Standard (USA)

1945 : Barrer 1949 : Borchert,(UK) Keidel (Germany)

1950 1953 : Barrer, 1953: Trief CementWhite (UK) (USA)1956 : Milton 1957: Glukovsky(USA) (Ukraine)

soil-silicate concrete1960 1963 : Howell (USA)

1964 : Berg et al.(USSR)1969 : Besson et al.(France)

1970 1972 : Davidovits 1976 : Davidovits(France) (IUPAC terminology)Siliface Process 1979 : Davidovits

(France)Geopolymer

Earlier, Flint & al (1946), at the National Bureau of Standardswere developing various processes for the extraction of alumina start-ing from clays and high-silica bauxites. One intermediary step of theextraction process involved the precipitation of a sodalite-like com-pound. Borchert and Keidel (1949) prepared hydrosodalite (NaPS)

12

Early observations

by reacting kaolinite in a concentrated NaOH solution, at 100C.Howell (1963) obtained a Zeolite A type, using calcined kaolin (meta-kaolin) instead of kaolinite, preventing the formation of hydrosoda-lite.

In 1972, the ceramicist team Jean Paul Latapie and Michel Davi-dovics confirmed that water-resistant ceramic tiles could be fabri-cated at temperatures lower than 450C, i.e. without firing. Onecomponent of clay, kaolinite, reacted with caustic soda at 150C. Infact, the industrial application of this kaolinite reaction with alkalibegan in the ceramic industry with Niels Olsen (1934) and was lateron reinvented in 1964 by Berg et al. (1970), a Russian team, butwithout any successful industrial implementation.

In 1969, Besson, Caillre and Hnin at the French Museum ofNatural History, Paris, carried out the synthesis of hydrosodalitefrom various phyllosilicates (kaolinite, montmorillonite, halloysite)at 100C in concentrated NaOH solution, (Besson et al., 1969).

In 1972, at CORDI laboratory in Saint-Quentin, we developed atechnology based on this geosynthesis, which has been disclosed invarious patents issued on the applications of the so-called "Siliface-Process" (Davidovits and Legrand, 1974). To a natural kaolinite/quartzblend (50/50 weight ratio) was added and mixed solid NaOH in theproportion of 2 moles or less of NaOH for 1 mole Al2O3 of the con-tained kaolinite, and water (11.5 g water for 1 g NaOH). The result-ing granules were cold-pressed at 15 MPa into a green body, whichwas then hot-pressed (thermosetting process) in a mold equippedwith a porous layer for water evaporation.

The thermosetting parameters were: Temperature: 130C to 180C; Applied hydraulic pressure: higher than the saturated vaporpressure of water, for the selected temperature, i.e. 10 to 30bars;

Time: one minute per millimeter thickness at 150C or 10 min-utes for a 10 millimeters thick plate. 65 to 75 % of the totaltime is devoted to degassing water.

The setting time is relatively short. In the absence of any perviousdevice, i.e. when degassing is not working, the polycondensation intohydrosodalite occurs very rapidly in a time as short as 1520 secondsper millimeter thickness, at 180C and 40 kg/cm2 hydraulic pressure.Yet, due to the high internal pressure of water and the danger ofexplosion, the press must be equipped with safety devices (see for

13

1. Introduction

more details in Chapter 7). Otherwise, it is recommended to waituntil the item has cooled down to room temperature before openingthe press.

1.4 Phosphate-based geopolymer

Phosphate ceramics are synthesized at room temperature and theyset rapidly like conventional polymers. They contain naturally occur-ring mineral phases, notably apatite. They represent another varietyof mineral geopolymer, where Si is totally or partially replaced by P.They are formed by an acid-base reaction between a metal oxide andan acid phosphate. Virtually any divalent or trivalent oxide that issparingly soluble may be used to form these phosphate geopolymers.

They have found a wide range of applications such as dental ce-ments, construction materials, oil well cements, and hazardous andradioactive waste stabilization. The main dierence between the si-licate based geopolymers and phosphate geopolymers, however, istheir syntheses. Poly(sialate) geopolymers and their derivates aresynthesized in alkaline environment, but phosphate geopolymers arefabricated by acid-base reactions.

1.4.1 Phosphate geopolymers

A very wide range of phosphate geopolymers may be synthesizedby acid-base reaction between an inorganic oxide (preferably thatof divalent and trivalent metals) and an acid phosphate. The reac-tion product is generally a poly(hydrophosphate) or an anhydrouspoly(phosphate) that consolidates into a ceramic. The following arethe most common examples (Wagh and Yeong, 2003; Wagh, 2004)

2CaO + Ca(H2PO4)2 + H2O )CaO + 2CaHPO4H2O ) Ca3(PO4)2 + 2H2O (1)

MgO + KH2PO4+ 5 H2O ) MgKPO46H2O (2)(Ceramicrete).

These reactions occur at room temperature. By controlling therate of reaction, ceramics can be formed. With trivalent oxides, sim-ilar ceramics can be formed at a slightly elevated temperature. A

14

Phosphate-based geopolymer

good example is berlinite (AlPO4), which is formed by the reactionbetween alumina and phosphoric acid:

Al2O3 + 2H3PO4 ) 2AlPO4 + 3H2O (3)

It was also demonstrated that phosphate geopolymers of trivalentoxides such as Fe2O3 and Mn2O3 might be produced by reductionof the oxide and then acid-base reaction of the reduced oxide withphosphoric acid. The reaction may be described by the followingequation:

X2O3 + X + 3H3PO4 + nH2O ) 3XHPO4(n+3)H2O (4)

where X is Fe or Mn.

1.4.2 High-molecular phosphate-based geopolymers:cristobalitic AlPO4

Berlinite (AlPO4) is the only known mineral to be isostructural withquartz. Isostructural means that they have the same structure al-though the two minerals have rather dierent chemistries. Quartz,SiO2, would seem to be very dierent from berlinite, AlPO4. But ifthe formula of quartz is written as SiSiO4 instead of 2(SiO2) then thesimilarity is obvious. The reason that berlinite is able to have thesame structure as quartz is because the aluminum and phosphorusions are of similar size to silicon ions with following bond lengthsSi-O 1,63 , P-O 1,63 , Al-O 1,73 . Thus the same structure canbe achieved since the aluminums and phosphorus can completely re-place the silicons without alteration of the quartz structure. Thecristobalite form of aluminum phosphate may be obtained by heat-ing the normal berlinite form of aluminum phosphate at an elevatedtemperature which is preferably in excess of 1000C.

The synthesis of cristobalitic (high-molecular) AlPO4 geopoly-mers follows two dierent routes. The first process includes sol-gelchemistry whereas the second system involves the reaction betweenphosphoric acid and metakaolinite MK-750 (see in Chapter 13).

15

1. Introduction

1.5 Organic-mineral geopolymers

1.5.1 Silicone

The similarity of the siloxane (Si-O-Si) structure in organo-siliconesto the chains, rings, and networks of silicon and oxygen found in silicaand the silicate minerals, for example in quartz, has been pointed outmany times. Almennigen et al. (1963) reported the correspondencein a study of disiloxane H6Si2O. As observed by Noll (1968) it ispossible to pass from the polymeric silicate to the polymeric covalentmolecules of an organosiloxane by replacing the bridging oxide ionsof the silicate anions with methyl groups. The structures that re-sult from this replacement closely resemble the silicate and alumino-silicate molecules: monomers, dimers, trimers, etc., rings, chains,sheets and frameworks of corner-sharing silicate [SiO4] groups.

Chapter 2 and Chapter 14 focus on silicone poly(organo-siloxane).When the organic radical is methylene the structures of the oligomericpoly-methyl-siloxanes are identical with those of poly(siloxonate) (Si-O-Si-O) and poly(sialate) (Si-O-Al-O-Si) geopolymers.

1.5.2 Humic-acid based: kerogen geopolymer

T.K. Yen and his team, working on the transformation of geomole-cules through geochemical processes during diagenesis, (Kim et al.,2004, 2006) have drawn attention to the concept of geopolymer inassociation with kerogen and petroleum. Kerogen-geopolymer is themost stable material and the final alternating product in the Earth.Some geopolymeric materials can last for a long time due to theirunique geopolymeric structure, so-called three-dimensional crosslink.Geopolymers can be classified into two major groups: pure inorganicgeopolymers and organic containing geopolymers, synthetic analogueof naturally occurring macromolecules (Kim et al., 2004, 2006). Thesmall content of organics is a key parameter governing the strengthand durability of material in a large volume of inorganics. Organiccompounds can be incorporated into refractory macromolecules suchas lignin and melanodin or humic materials (Henrichs 1992). Humicmaterials represent an inorganic-organic structure.

Diagenesis of organic matter leads from biopolymers synthesizedby organisms through "humin" to Kerogen, a geopolymer, by partialdestruction and rearrangement of the main organic building blocks

16

Organic-mineral geopolymers

Figure 1.4: Evolution of organic matter to kerogen-geopolymer

(Figure 1.4). Kerogen is considered to be the major starting mate-rial for most oil and gas generation as sediments are subjected togeothermal heating in the subsurface. It is the most abundant formof organic carbon on Earth, about 1000 times more abundant thancoal, which forms primarily from terrigenous remains of higher plants.Kerogen is a geopolymer that contains a high content of organics.Kerogen geopolymers generally occur in numerous forms: some havemore organics and less inorganics, while others have the opposite. Itis, however, evident that both inorganics and organics are requiredin a mix at a certain ratio, which will result in a geopolymeric struc-ture. This geopolymeric structure exhibits a similar organizationto human bone and teeth, typical inorganic-organic composites thatshow extreme durability and mechanical strength. The mechanism ofgeomacromolecule formation involves the crosslink reaction betweenthe inorganic and organic materials.

References

Almennigen, A., Bastiansen, O., Ewing, V., Hedberg, K. and Traetteberg, M.,(1963), Acta Chem. Scand. 17, 24552460.

17

1. Introduction

Berg L.C., Demidenko B.A., Reminikova V.I. and Nisamov N.S., (1970), Stroi-telnye Materialy (USSR), 10, 22.

Besson H., Caillre S. and Henin S., (1969), Conditions de prparation de lhydro-sodalite basse temprature, C. Rend. Acad. Sci., D269, 1367.

Borchert W. and Keidel J., (1949), Heidelb. Beitr. z. Min. u. Petr., 1. 2.Davidovits J., (1972), Procd de fabrication de panneaux agglomrs et pan-neaux resultant de lapplication de ce procd, French Patent ApplicationFR 72.38746 (FR 2,204,999) and FR 73.35979 (FR 2,246,382); US Patent3,950,470, Process for the fabrication of sintered panels and panels resultingfrom the application of this process.

Davidovits J. and Legrand J.-J., (1974) French Patent FR 2,324,427 filed Jan.11. 1974; see also US Patent 4,028,454 (1977), filed Dec. 31. 1974 ; UnitedKingdom Patent UK 1.481.479 (1977), filed Jan. 9, 1975; German Patent DE25 00 151 (1979), filed Jan. 3, 1975.

Davidovits J., (1976), Solid phase synthesis of a mineral blockpolymer by lowtemperature polycondensation of aluminosilicate polymers, IUPAC Interna-tional Symposium on Macromolecules Stockholm; Sept. 1976; Topic III, NewPolymers of high stability.

Davidovits J., (1979), Polymre Minral, French Patent Application FR 79.22041(FR 2,464,227) and FR 80.18970 (FR 2,489,290); US Patent 4,349,386, Min-eral polymer.

Davidovits J., (1993), Carbon-Dioxide Greenhouse-Warming: What Future forPortland Cement, Proceedings, Emerging Technologies Symposium on Cementand Concrees in the Global Environment, 21p, Portland Cement Association,Chicago, Illinois, March 1993.

Davidovits J. and Sawyer J.L., (1985), Early high-strength mineral polymer, USPatent 4,509,985, 1985, filed February 22, 1984.

Davidovits J. and Comrie D., (1988), Archaeological long-term durability of haz-ardous waste disposal: preliminary results with geopolymer technologies, Divi-sion of Environmental Chemistry, American Chemical Society, Toronto, 1988,Extended Abstracts, 237240. See also: Long Term Durability of HazardousToxic and Nuclear Waste Disposals, Geopolymer 88 Proceedings, 125134.

Davidovits J. and Davidovics M., (1991), Geopolymer: Ultra-High TemperatureTooling Material for the Manufacture of Advanced Composites", SAMPE Sym-posium, Vol.36, 2, pp. 19391949, Society for the Advancement of Material andProcess Engineering, Covina, California, USA.

Flint E.P., Clarke W.F., Newman E.S., Shartsis L., Bishop D.L. and Wells L.S.,(1946), J. Res. Nat. Bur. Stand., 36, 63.

GEOASH (20042007), The GEOASH project was carried out with a financialgrant from the Research Fund for Coal and Steel of the European Community.The GEOASH project is known under the contract number RFC-CR-04005.It involved: Antenucci D., ISSeP, Lige, Belgium; Nugteren H.and Butselaar-Orthlieb V., Delft University of Technology, Delft, The Netherlands; Davi-dovits J., Cordi-Gopolymre Sarl, Saint-Quentin, France; Fernndez-PereiraC. and Luna Y., University of Seville, School of Industrial Engineering, Sevilla,Spain; Izquierdo and M., Querol X., CSIC, Institute of Earth Sciences "JaumeAlmera", Barcelona, Spain.

Geocistem (1997), BRITE-EURAMEuropean research project BE-7355-93, GEO-CISTEM, Synthesis Report and Final Technical Report, July 1997. GEOCIS-

18

Organic-mineral geopolymers

TEM is the acronym for "cost eective GEOpolymeric Cements fo InnocuousStabilisation of Toxic EleMents". The primary objective of the Geocistem re-search project was the fabrication of alkali-melilitic glass (Ca,Na,K)2[(Mg,Fe2+,Al,Si)3O7]. Vitrification at temperatures ranging from 1200C to 1350C andmineral binder formulations were performed by J. Davidovits in the labora-tory of Cordi-Gopolymre SA, Saint-Quentin, France. The selection of Euro-pean geological materials was carried out by P. Rocher, BRGM Bureau deRecherches Gologiques et minires, Orlans, France, D. Gimeno, GeologyDept. University of Barcelona, Spain, C. Marini and S. Tocco, University ofCagliari, Italy. MAS-NMR spectroscopy was performed by Z. Gabelica at thattime in Namur University, Belgium.

Glukhovsky V.D., (1965), Soil silicates, Their Properties, Technology and Man-ufacturing and Fields of Application, Doct Tech Sc. Degree thesis. Civil Engi-neering Institute, Kiev, Ukraine (former USSR).

Heitzmann R.F, Gravitt, B.B. and Sawyer, J.L., Cement Composition Curableat Low Temperature, US Patent 4,842,649, 1989.

Henrichs S.M., (1992), Early diagenesis of organic matter in marine sediments:progress and perplexity. Mar. Chem. 39, 119149.

Hermann E, Kunze C., Gatzweiler R., Kiessig G. and Davidovits J., (1999), Solid-ification of various radioactive residues by Geopolymere with special emphasison long-term stability, Geopolymer 99 Proceedings, 211228.

Howell P.A., (1963), US Patent 3,114,603.Kim D., Lai H.-T., Chilingar G.V., Yen T.F., (2006), Geopolymer formation andits unique properties, Environ. Geol, 51[1], 103111.

Kim D., Petrisor I.G., Yen T.F., (2004), Geo-polymerization of biopolymers: apreliminary inquiry. Carbohyd Polym. 56, 213217.

Lyon R.E, Foden A.J., Balaguru P., Davidovits J. and Davidovics M., (1997),Properties of Geopolymer Matrix-Carbon Fiber Composites, Fire and Materi-als, 21. 6773.

Neuscher K.H., Engels H.W., Gebert H.J., Laube R.W. and Zoche G., (1985),US Patent 4,522,652 ; see also K.H. Neuscher, P. Spielau, G. Zoche andH.W. Engels US Patent 4,533,393 (1985); K.H. Neuscher, P. Spielau, H.W.Engels and G. Zoche US Patent 4,608,795 (1986).

Noll W., (1968), Chemistry and Technology of Silicone, Academic Press, N.Y. inparticular, Chapter 6.3 (pp. 287 -317) on the "Siloxane Bonds in Molecules ofSiloxanes and Anions of Silicates."), (First published in the German languageunder the title "Chemie und Technologie der Silicone", 1960, Verlag Chemie,Germany).

Olsen N., (1934), German Patent 600,327.Purdon A.O., (1940), Laction des alcalis sur le laitier de haut-founeau (Theaction of alkalis on blast furnace slag), Journal de la Socit des IndustriesChimiques, Bruxelles, Belgium, (Journal of the Society of Chemical Industry),59, 191202.

US Army Corps of Engineers, (1986), Malone P.G., Randal C.A. and KirkpatrikT., Potential for Use of Alkali-Activated Silico-Aluminate Binders in MilitaryApplications, Report WES/MP/GL-85-15, Corps of Engineers, Vicksburg, Mis-sissipi.

US Army Corps of Engineers, (1994), Performance of Concretes Proportionedwith Pyrament Blended Cement, by Tony B. Husbands, Philip. G. Malone,

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1. Introduction

Lilian D. Wakeley, US Army Corps of Engineers, Final Report CPAR-SL-94-2,April 1994.

Vautey P., (1990), Thermoplastic and Thermosetting Composites for StructuralApplications, Comparison of Mechanical Properties, French Aerospace 90 Aero-nautical Conference, Washington, D.C., June 1214, 1990 pp. 122.

Wagh A.S., and Jeong S.Y., (2003), Chemically Bonded Phosphate Ceramics: I.A Dissolution Model of Formation, J. Ceram. Soc., 86 [11] 18381844.

Wagh A.S., (2004), Chemically Bonded Phosphate Ceramics A Novel Class ofGeopolymers, Proceedings of the 106th Ann. Mtg. of the American CeramicSociety, Indianapolis.

Publications of the Geopolymer Institute(www.geopolymer.org)

Geopolymer 88, Proceedings of the First European Conference on Soft Miner-alulgy, June 1988, Compigne, France, edited by Joseph Davidovits and JosephOrlinski.

Geopolymere 99, Proceedings of the Second International Conference Gopo-lymre 99, Saint-Quentin, France, June 30-July 2, 1999, edited by JosephDavidovits, Ralph Davidovits and Claude James.

Geopolymer 2005, Proceedings of the World Congress Geopolymer 2005, Geopo-lymer, Green Chemistry and Sustainable Development Solutions, 4th Interna-tional Geopolymer Conference, Saint-Quentin, France, July 2005, GeopolymerWorkshop, Perth, Australia, Sept. 2005, edited by Joseph Davidovits.

Geopolymer Chemistry and Applications, by Joseph Davidovits, 1st edition march2008, 2nd edition June 2008,

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