International Conference on TIM, 2012, Nepal
Synthesis and Characterization of Geopolymer from
Various Types of Construction Wastes
Arvind Pathak, Ambar B. Rangu Magar, Dipak Paudel,
Rishi B. Bhandari and Vinay Kumar Jha
Central Department of Chemistry
Institute of Science and Technology
Tribhuvan University
Kathmandu, Nepal
October 10-12, 2012
International Conference on TIM, 2012, Nepal
Abstract
Construction wastes such as coal fly ash (CFA), demolished
cement-sand-mixture (DCSM), demolished cement sand-concrete
mixture (DCSCM), brick dust (BD) are rich sources of aluminosilicate and thus can be used as raw material for the synthesis of
geopolymer.
Geopolymers have been synthesized from construction wastes
using alkali and alkali-silicate as activators.
Geopolymerization can transform a wide range of alumino-silicate
materials into building materials with excellent physicochemical
properties such as fire, acid and earthquake resistant.
Geopolymers have been synthesized from CFA, DCSM, DCSCM and
BD of compressive strength 41.9, 47.0, 45.5 and 60.0 MPa
respectively.
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International Conference on TIM, 2012, Nepal
Introduction
Geopolymer is a class of synthetic
aluminosilicate materials. It has a number of
potential uses in several areas but
predominantly as replacement of cement.
The name “GEOPOLYMER” was first
given to these materials by Prof. John
Davidovits in 1970.
The existence of geopolymer can be seen in
Egypt’s famous Pyramids. Roman cement
and small artifacts, which were previously
thought to be stone, were made using the
knowledge of geopolymer techniques.
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International Conference on TIM, 2012, Nepal
Some Features of Geopolymer
Ceramics
Concrete sleepers
Paver
Land slide
stabilization
Precast structural pipes
Hazardous waste
encapsulation 4
International Conference on TIM, 2012, Nepal
Geopolymer and Portland cement
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International Conference on TIM, 2012, Nepal
Geopolymer and Portland cement
Hardening of Portland
cement
(P.C.)
through
simple
hydration
of
calcium
silicate
into
calcium di-silicate hydrate
and lime Ca(OH)2.
Hardening of Geopolymer
resin (GP) through polycondensation of potassium
oligo-(sialate-siloxo) into
potassium
poly(sialatesiloxo) cross linked network.
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International Conference on TIM, 2012, Nepal
Geopolymer and Portland cement
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International Conference on TIM, 2012, Nepal
Objectives

To
synthesize
geopolymer
from
the
construction
waste
with
comparable
compressive strength like ordinary cement
materials.

To reduce the CO2 emission in the atmosphere.

To reduce the disposal problem of construction
wastes.
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International Conference on TIM, 2012, Nepal
Basic Mechanism of Geopolymerization
Construction
Waste
Sodium Silicate
Sodium
Hydroxide
Geopolymer
Smaller particle size of construction waste, sodium silicate and
higher content of alkali metals enhance the dissociation and
dissolution of alumino-silicate and thereby the formation of
geopolymer will have positive influence.
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International Conference on TIM, 2012, Nepal
Geopolymer Structure
Barboca et al., 2000
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International Conference on TIM, 2012, Nepal
Compressive Strength and XRD Pattern
Measurements
SLF 9 Load frame machine
Bruker, D8 Advance
Diffractometer
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International Conference on TIM, 2012, Nepal
XRD-Patterns
S
Q: Quartz
Q: Quartz, S: silica, C: calcite, M: mullite, R: rutile
53 m
QS
90 m
C
M
Q R
C
75 
Intensity (a.u.)
75 m
Intensity (a.u.)
Intensity (a.u.)
53 
53 m
M
75 m
R
C
90 m
Q
120 m
Q
90 
Q
A
Q
120 
10
20
CuK 2
BD
30
40
10
20
30
40
CuK 2
DCSCM
50
60
Q
Q
120 m
10
20
30
40
50
CuK 2
DCSM
12
60
International Conference on TIM, 2012, Nepal
Comp. Strength With NaOH Variation
8
DCSCM+NaOH
Compressive strength (MPa)
7
BD+NaOH
CFA+KOH
6
DCSM+NaOH
5
4
3
2
1
0
0
2
4
6
8
10
NaOH concentration (M)
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International Conference on TIM, 2012, Nepal
Compressive strength (MPa)
Comp. Strength With Particle Size Variation
9
8
BD
DCSCM
DCSM
7
6
5
4
3
2
1
0
53
75
90
Particle size (m)
120
150
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International Conference on TIM, 2012, Nepal
Compressive strength (MPa)
Comp. Strength With Na2SiO3/CW ratio
45
40
35
30
25
20
15
10
5
0
DCSCM
DCSM
0.5
BD
CFA
1.0
1.5
1.75
2.0
Na2SiO3 to construction wastes mass ratio
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International Conference on TIM, 2012, Nepal
Comp. Strength With Curing Time Variation
Compressive strength (MPa)
70
BD
DCSM
60
DCSCM
CFA
y = 2.169x - 0.325
R² = 0.9812 (BD)
50
y = 1.461x + 10.018
R² = 0.8122 (DCSM)
40
y = 1.2284x + 8.523
R² = 0.9884 (CFA)
30
20
10
y = 1.5055x + 3.1472
R² = 0.9926 (DCSCM)
0
0
5
10
15
20
Curing time (Days)
25
30
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International Conference on TIM, 2012, Nepal
Characterization of Geopolymer Products
Q
CFA-based
M
Intensity (a.u.)
S
DCSM-based
DCSCM-based
Q
10
20
BD-based
30
40
50
60
CuK 2
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International Conference on TIM, 2012, Nepal
Conclusion
 The most suitable raw material for the synthesis of
geopolymer is brick-dust.
 Geopolymeric products of compressive strength more
than 40 MPa was obtained with all types of construction
wastes. Furthermore, with brick dust geopolymer of 60
MPa was achieved
 Thus Produced geopolymer can provide better alternate
for ordinary cement.
 This will solve the problem of disposal and hence
Geopolymers could turn construction waste into wealth.
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International Conference on TIM, 2012, Nepal
Acknowledgements

Associate Prof. Dr. Vinay Kumar Jha, Central Department of
Chemistry, Tribhuvan University.

Nepal Academy of Science and Technology (NAST) for Ph.D.
Fellowship and financial support (Project 2067/68).

Central Material Testing Laboratory, Institute of Engineering
(IOE), Pulchowk Campus, Tribhuvan University, Kathmandu.

Assoc. Prof. Dr. Lalu Prasad Paudel, Head of Central Dept. of
Geology, T. U., Kirtipur, Kathmandu for his valuable help in XRay diffraction measurement of samples.

Central Department of Chemistry, Tribhuvan University for
providing me the necessary facilities to carry out my Doctoral
study.

Organizing Committee and TIM Conference-2012 Team.
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