tribhuvan university kathmandu, nepal arvind pathak, ambar b. rangu magar, dipak paudel, rishi b....

Tr ibhuvan Univers i ty

Kathmandu, Nepal

Arvind Pathak, Ambar B. Rangu Magar, Dipak Paudel, Rishi B. Bhandari and Vinay Kumar Jha

Central Department of Chemistry

Institute of Science and Technology

October 10-12, 2012

International Conference on TIM, 2012, Nepal

Synthesis and Characterization of Geopolymer from Various Types of Construction Wastes

AbstractConstruction 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 alumino-silicate 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. 2


IntroductionGeopolymer 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.

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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.


Some Features of Geopolymer

Paver

Land slide stabilization

Ceramics

Hazardous waste encapsulation

Precast structural pipes

Concrete sleepers 4


Geopolymer and Portland cement

5



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 poly-condensation of potassium oligo-(sialate-siloxo) into potassium poly(sialate-siloxo) cross linked network. 6



7


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.

8


Basic Mechanism of Geopolymerization

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.

Construction Waste

9


Sodium Silicate Sodium Hydroxide

Geopolymer

Barboca et al., 2000

Geopolymer Structure

10


Compressive Strength and XRD Pattern Measurements

SLF 9 Load frame machine Bruker, D8 Advance Diffractometer 11


XRD-Patterns

Inte

nsity

(a.

u.)

CuK 2

120 m

90 m

75 m

53 m

Q

Q

Q: Quartz, S: silica, C: calcite, M: mullite, R: rutile

M

C

Q

S

R

10 20 30 40 50 60

Inte

nsity

(a.

u.)

CuK 2

120 m

90 m

75 m

53 m

Q

Q

Q: Quartz

10 20 30 40

Inte

nsity

(a.

u.)

CuK 2

120

90

75

53

Q

S

Q

M C C Q R

A

10 20 30 40 50 60

BD DCSCM DCSM

12


Comp. Strength With NaOH Variation

1 2 3 4 5 6 7 8 90

1

2

3

4

5

6

7DCSCM+NaOH

BD+NaOH

CFA+KOH

DCSM+NaOH

Com

pres

sive

str

engt

h (M

Pa)

NaOH concentration (M)

13


Comp. Strength With Particle Size Variation

0

1

2

3

4

5

6

7

8

9

5375

90120

150

Com

pres

sive

str

engt

h (M

Pa)

Particle size (m)

BD DCSCM DCSM

14


Comp. Strength With Na2SiO3/CW ratio

0.51.0

1.51.8

2.0

0

5

10

15

20

25

30

35

40

45 DCSCM BDDCSM CFA

Na2SiO3 to construction wastes mass ratio

Com

pres

sive

str

engt

h (M

Pa)

15


Comp. Strength With Curing Time Variation

y = 2.169x - 0.325R² = 0.9812 (BD)

y = 1.5055x + 3.1472R² = 0.9926 (DCSCM)

y = 1.461x + 10.018R² = 0.8122 (DCSM)

y = 1.2284x + 8.523R² = 0.9884 (CFA)

0

10

20

30

40

50

60

70

0 5 10 15 20 25 30

Com

pres

sive

str

engt

h (M

Pa)

Curing time (Days)

BD DCSCMDCSM CFA

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Characterization of Geopolymer Products

Inte

nsity

(a.

u.)

CuK 2

CFA-basedQ

Q

DCSM-based

DCSCM-based

BD-based

SM

10 20 30 40 50 60

17


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.

Conclusion

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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 X-Ray 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. 19


THANK YOU

tribhuvan university kathmandu, nepal arvind pathak, ambar b. rangu magar, dipak paudel, rishi b....

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