The document provides an overview of geopolymers, including: 1) Geopolymers are inorganic materials that form long-range, covalently bonded networks, and were coined in 1978. 2) They have various uses such as fire-resistant coatings and encapsulating toxic waste. 3) Their microstructure is amorphous at room temperature but crystalline at over 500 degrees Celsius.

1. Nishant Raj Kapoor
“Geopolymers”
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2. OVERVIEW OF PRESENTATION
 Introduction
 Uses of geopolymer
 Types of polymers
 Microstructure of geopolymer
 First presentation of geosynthesis
 Geopolymers synthesis routes
 References
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3. INTRODUCTION
Geopolymers are inorganic, typically ceramic, materials that
form long-range, covalently bonded, non-crystalline
(amorphous) networks.
Obsidian (volcanic glass) fragments are a component of some
geopolymer blends.
Joseph Davidovits coined the term in 1978 and created the non
profit French scientific institution (Association Loi 1901)
Institut Géopolymère (Geopolymer Institute).
Source: Kozhukova, N.I.; Chizhov, R.V.; Zhervovsky, I.V.; Strokova, V.V. (2016).
Structure Formation of Geopolymer Perlite Binder Vs. Type of Alkali Activating
Agent, International Journal of Pharmacy & Technology, vol. 8, iss. no. 3, pp.
15,339.
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4. For alkali-cement scientists…
“Geopolymers are framework structures produced by
condensation of tetrahedral aluminosilicate units, with alkali
metal ions balancing the charge associated with tetrahedral Al.
Conventionally, geopolymers are synthesized from a two-part
mix, consisting of an alkaline solution (often soluble silicate) and
solid aluminosilicate materials. Geopolymerization occurs at
ambient or slightly elevated temperature, where the leaching of
solid aluminosilicate raw materials in alkaline solutions leads to
the transfer of leached species from the solid surfaces into a
growing gel phase, followed by nucleation and condensation of
the gel phase to form a solid binder.”
Source: Feng, Dingwu; Provis, John L. and van Devente,r Jannie S. J. (2012)
(University of Melbourne, Australia), Thermal Activation of Albite for the Synthesis of
One-Part Mix Geopolymers, J. Am. Ceram. Soc., 95 [2] 565–572.
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DEFINITIONS OF THE TERM GEOPOLYMER

5. For geopolymer material chemists…
“The reaction produces SiO4 and AlO4, tetrahedral frameworks
linked by shared oxygens as poly(sialates) or poly(sialate–
siloxo) or poly(sialate–disiloxo) depending on the SiO2/Al2O3
ratio in the system. The connection of the tetrahedral
frameworks is occurred via long-range covalent bonds. Thus,
geopolymer structure is perceived as dense amorphous phase
consisting of semi-crystalline 3-D alumino-silicate
microstructure.”
Source: Pimraksaa, K.; Chindaprasirt, P.; Rungchet, A.; Sagoe-Crentsil, K. and
Sato, T. (2011) (Department of Industrial Chemistry, Chiang Mai University,
Thailand; CSIRO, Melbourne, Australia; Tohoku University, Sendai, Japan),
Lightweight geopolymer made of highly porous siliceous materials with various Na
2O/Al2O3 and SiO2/Al2O3 ratios, Materials Science and Engineering A , 528,
6616–6623
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DEFINITIONS OF THE TERM GEOPOLYMER

6. For geopolymer ceramic chemists…
“Although geopolymer is generally X-ray amorphous if
cured at standard pressures and temperatures, it will
convert into crystalline ceramic phases like leucite or
pollucite upon heating.”
Source: Peigang He, Dechang Jia, Meirong Wang, Yu Zhou, (2011) (Harbin
Institute of Technology, Harbin, PR China:), Thermal evolution and crystallization
kinetics of potassium-based geopolym,e rCeramics International, 37, 59–63.
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DEFINITIONS OF THE TERM GEOPOLYMER

7. DEFINITIONS OF THE TERM GEOPOLYMER
For chemists…
“...Geopolymers consist of a polymeric Si–O–Al framework,
similar to zeolites. The main difference to zeolite is
geopolymers are amorphous instead of crystalline. The
microstructure of geopolymers on a nanometer scale observed
by TEM comprises small aluminosilicate clusters with pores
dispersed within a highly porous network. The clusters sizes are
between 5 and 10 nanometers.”
Source: Huang, Yi and Han, Minfang (2011) (China University of Mining
and Technology, Beijing), The influence of α-Al 2O3 addition on
microstructure, mechanical and formaldehyde adsorption properties of fly
ash-based geopolymer products, Journal of Hazardous Materials , 193, 90–
94
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8. USES OF GEOPOLYMERS
Commercially produced geopolymers may be used for:
 Fire- and heat-resistant coatings and adhesives
 Medicinal applications
 High-temperature ceramics
 New binders for fire-resistant fiber composites
 Toxic and radioactive waste encapsulation
 New cements for concrete.
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9. TYPES OF POLYMERS
 Organic Polymer (carbon based)
 Inorganic Polymer (silicon based)
The organic polymers comprise the classes of:
 Natural polymers (rubber, cellulose)
 Synthetic organic polymers (textile fibers, plastics, films)
 Natural biopolymers (biology, medicine, pharmacy)
Raw materials used in the synthesis of silicon-based polymers are
mainly rock-forming minerals of geological origin, hence the name:
geopolymer.
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10. MICROSTRUCTURE OF GEOPOLYMER
The microstructure of geopolymers is essentially
temperature dependent.
It is X-ray amorphous at room temperature, but evolves
into a crystalline matrix at temperatures above 500 °C.
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11. FIRST PRESENTATION OF GEOSYNTHESIS
According to T.F. Yen,
A geopolymer is essentially a mineral chemical compound or
mixture of compounds consisting of repeating units, created
through a process of geopolymerization.
For example:
 silico-oxide (-Si-O-Si-O-)
 silicoaluminate (-Si-O-Al-O-)
 ferro-silico-aluminate (-Fe-O-Si-O-Al-O-)
 alumino-phosphate (-Al-O-P-O-)
This mineral synthesis (geosynthesis) was first presented at an
IUPAC symposium in 1976.
Source: Kim, D.; Lai, H.T.; Chilingar, G.V.; Yen T.F. (2006), Geopolymer
formation and its unique properties, Environ. Geol, 51[1], 103–111
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12. GEOPOLYMERS SYNTHESIS ROUTES
One can distinguish between two synthesis routes:
 In alkaline medium (Na+, K+, Li+, Ca2+, Cs+ etc.)
 In acidic medium with phosphoric acid, organic carboxylic
acids from plant extracts (acetic, citric, oxalic, and humic
acids).
The alkaline route is the most important in terms of research
and development and commercial applications.
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13. REFERENCES
 www.google.com
 www.wikipedia.com
 www.researchgate.net
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14. TO BE CONTINUED…
Geopolymerization is the process of combining
many small molecules known as oligomers into a
covalently bonded network.
Source: North, M.R. and Swaddle, T.W. (2000). Kinetics of Silicate
Exchange in Alkaline Aluminoislicate Solutions, Inorg. Chem., 39,
2661–2665.
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15. THANKS
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