2. Contents
Abstract
Introduction to Geopolymer
Geopolymerization Mechanism
Objectives of the study
Literature review
Materials Utilised
Preparation Of Geopolymer Concrete
Experimental Investigation On Geopolymer Concrete
Illustrative Example On Geopolymer Concrete Mix Design
Experimental Investigation On Mix Design Procedure
Result And Discussion On Geopolymer Concrete
3. ABSTRACT
Fly ash-based geopolymer concrete mixtures for different grades were
studied in this work and made a Mix design procedure relevant to
Indian Cement concrete Mix design standard (IS 10262-1982) with
some modification for river sand as well as the manufactured sand.
In this Sodium hydroxide and sodium silicate solution were used as
alkali activators for mix proportions.
Water was added to control the concrete Slump i.e. workability.
All the specimens were cured at temperature of 60ºC for about the
period of 36 hours in the curing chamber. Then test for compressive
strength, Tensile strength.
The results show that high alkalis activated geopolymer Mixers can be
used as cementations’ material in place of Portland cement for making
concrete as given procedure.
Then the investigation carried out on reinforced geopolymer concrete,
for this mix design with grade M25 and M30 is used
4. The beam is designed for the flexural failure as per IS 456-2000.
The test results shows that the reinforced geopolymer concrete strength
is 68% higher than that of the conventional concrete for both M-sand
and River sand.
Thus utilize of these waste material we can control the global warming
i.e. CO2 producing Portland cement can be reduced. From this
investigation we assure that future precast member can be of in
Geopolymer concrete.
5. Introduction
Development of amorphous to semi-crystalline three-dimensional
silico-aluminate materials, which is called in French "géopolymères", i.e.
Geopolymers (mineral polymers resulting from geo-chemistry or
geosynthesis).
Geopolymer concrete is produced without the presence of Portland cement.
The base material.
Flyash
flyash, that is rich in Silicon (Si) and Aluminium (Al), is activated by
alkaline solution to produce the binder i.e. Sodium hydroxide and
sodium silicate.
Aggregates
Fine aggregate
River sand or Manufactured sand Matching with IS515 or IS 383
Course Aggregate
Crushed with angular aggregate
Applications of Geopolymeric Materials Based
Bricks, Ceramics
6. Geopolymers
Amorphous macromolecules that result from the
alkali activation of aluminosilicate minerals at
relatively low temperatures
Al3+ and Si4+ IV-fold coordination with oxygen
PS
PSS
PSDS
Davitovits, J. Journal of Materials Education 1994, 16, 91-139
7. Components
Sources of silica and aluminum
Metakaolin
Dehydroxylated kaolinite
2(Si2O5·Al2(OH)4)n 2(Si2O5·Al2O2)n + 4n H2O
Fly Ash
Silicon Dioxide
Slag
Aluminum and Silica Oxides
Alkaline Activator
Alkali hydroxide or alkali silicate solution
Usually Na, K
8. Geopolymerization Mechanism
Step 1: alkalination and formation of tetravalent Al in the side
group sialate -Si-O-Al-(OH)3-Na+
Step 2: alkaline dissolution starts with
the attachment of the base OH- to the
silicon atom
Davitovits, J. Journal of Thermal Analysis 1991, 37, 1633-1656
9. Geopolymerization Mechanism Cont.
Step 3: cleavage of the oxygen in Si-O-Si through transfer of the
electron from Si to O.
Step 4: further formation of silanol Si-OH groups and isolation of the
ortho-sialate molecule, the primary unit in geopolymerization.
11. Geopolymerization Mechanism Cont.
Step 6a: condensation between reactive groups Si-O-
Na and aluminum hydroxyl OH-Al, with production of
NaOH, creation of cyclo-tri-sialate structure, further
polycondensation into Na-poly(sialate) nepheline
framework.
12. Geopolymerization Mechanism Cont.
Step 6b: in the presence of soluble Na- polysiloxonate one gets creation
of ortho-sialate-disiloxo cyclic structure, whereby the alkali NaOH is
liberated and reacts again
13. Geopolymerization Mechanism Cont.
Step 7: further
polycondensation into Na-
poly(sialate-disiloxo) albite
framework with its typical
feldspar crankshaft chain
structure.
15. OBJECTIVES OF THE STUDY
To establish the Mix design guide lines based on compressive
strength.
Enhance the behaviour of the geopolymer concrete
Flexural study on Reinforced Geopolymer concrete.
16. LITERATURE REVIEW
Hardjito and B Vijaya Rangan, (2005):
Higher concentration (in terms of molar) of sodium hydroxide solution
results in higher compressive strength of geopolymer concrete. Higher the
ratio of sodium silicate solution-to-sodium hydroxide solution ratio by mass,
higher is the compressive strength of geopolymer concrete.
Caijun Shi and Jushi Quian (2003)
“Increasing up to 60% of coal fly ash use in cement and concrete through
chemical activation.
Rafat Siddique (2004)
Carried out an experimental investigation which deals with concrete
incorporating high volume of class F fly ash Portland cement was replaced
by 100% respectively with class F fly ash. Tests were performed for both
fresh and hardened concrete properties.
17. Baltimore (2003),
Characteristic of chemically Activated fly ash (CAFA), CAFA
concrete is a new development in fly ash cementious material
technology. CAFA concrete is produced using conventional concrete
mixing and forming techniques. CAFA requires dry curing at
elevated temperature of 50 to 93 degree Celsius making it feasible
for production of pre-cast concrete products .CAFA concrete has HP
proper ties including rapid strength gain (up to 90.5 of 28days
compressive strength in 24 hours).
Apha Sathonsaowaphaka, Prinya Chindaprasirt, Kedsarin
Pimraksa (2009)
Workability and strength of lignite bottom ash geopolymer mortar.
18. MATERIALS UTILISED
Fly ash
In this investigation, fly ash is obtained from Mettur Thermal Power Plant,
Mattur.
Physical Properties Values
Finesses modulus
(passing through 45
micro meter)
7.86
Specific gravity 2.30
Chemical
properties
min% by mass
IS:3812-
1981
Fly ash
MTPP
SiO2+Al2O3+Fe2
O3,
70% 90.5%
SiO2 35% 58%
CaO 5% 3.6%
SO3 2.75% 1.8%
Na2O 1.5% 2%
L.O.I 12% 2%
MgO 5% 1.91%
19. FINE AGGREGATE
Clean and dry river sand available locally belongs to zone III as per IS 383 is
used for casting the specimens.
MANUFACTURED SAND
Clean and Saturated surface dry sand locally belongs to zone II as per IS 383
Msand is used for casting the specimens.
S. No. Properties Values
1 Specific Gravity 2.67
S. No. Properties Values
1 Specific Gravity 3.1
20. COURSE AGGREGATE
Crushed granite aggregate with specific gravity of 2.7 and passing through
20 mm sieve and retained on 10 mm has been used for casting all
specimens.
WATER
Water is added for dissolving the solvents and extra water is added as per
the workability of concrete mix procedure. As said in IS 456-2000 the
standard of water should match it.
21. Sodium Hydroxide
In this investigation low cost the sodium hydroxide pellets were used.
i.e. up to 94% to 96% purity.
Physical properties
Colour Colour less
Specific Gravity
20% 1.22
30% 1.33
40% 1.43
50% 1.53
Chemical properties
Assay 97% Min
Carbonate
(Na2CO3)
2% Max
Chloride (Cl) 0.01% Max
Sulphate (SO2) 0.05% Max
Lead (Pb) 0.001% Max
Iron (Fe) 0.001% Max
Potassium (K) 0.1% Max
Zinc (Zn) 0.02% Max
22. Sodium silicate solution
Sodium silicate also known as water glass or liquid glass, available in
liquid (gel) form. In present investigation sodium silicate 2.0 (ratio
between Na2O to SiO2) is used.
As per the manufacture, silicates were supplied to the detergent
company and textile industry as bonding agent.
Note:
We recommended the sodium silicate whose specific gravity lies
between 1.55 to 1.65 and Sodium to silicate ratio must be within 2.0
23. Physical and Chemical Properties Sodium
Silicate
Chemical formula Na2O x SiO2 Colour less
Na2O 15.9%
SiO2 31.4%
H2O 52.7%
Appearance Liquid (Gel)
Colour Light yellow Liquid (gel)
Boiling Point 102 C for 40% acqeous
solution
Molecular Weight 184.04
Specific Gravity 1.6
Solid Particle of Sodium silicate
24. PREPARATION OF GEOPOLYMER CONCRETE
Preparation Alkaline Liquids:
Sodium Hydroxide
Sodium hydroxide pellets are taken and dissolved in the water at the
rate of 16 molar concentrations.
It is strongly recommended that the sodium hydroxide solution must be
prepared 24 hours prior to use and also if it exceeds 36 hours it
terminate to semi solid liquid state.
Molarity Calculation
NaOH solution with a concentration of 16 Molar consists of 16 x 40 =
640 grams of NaOH solids per litre of the water, were 40 is the
molecular weight of NaOH.
10 Molar: 314 grams, 12 Molar: 361 grams, and 14 Molar: 404 grams ,
16 molar : 444 grams (Hardjito and Rangan, 2005).
25. Alkaline Liquid:
The solution mixed together start to react i.e. (polymerisation takes
place) it liberate large amount of heat so it is recommended to leave it
for about 20 minutes thus the alkaline liquid is get ready as binding
agent
Mixing And Flow Tests
The aggregates were prepared in saturated-surface-dry (SSD)
condition
Geopolymer concrete can be manufactured by adopting the
conventional techniques used in the manufacture of Portland cement
concrete.
Right after the mixing, the flow value of fresh geopolymer
concrete was determined in accordance with slump test IS 516.-1959
The fresh concrete could be handled up to 120 minutes without
any sign of setting and without any degradation in the compressive
strength
26. Flow test (workability) was carried out by slump cone test as described
for cement concrete
The specimens were left standing for 1 hour and then cured at 60ºC in
the curing chamber for about 36 hours.
Demoulding was done at 24 hours at the time of curing age.
After the curing period the specimens left at the room temperature for
about an hour and ready for testing.
Thus the compressive strengths and tensile strength of concrete were
tested at the same day in accordance with IS 516.-1959
Ingredients of Geopolymer concrete
27. Fig Shows the Mixing, Slump and placing of
Geopolymer concrete
37. ILLUSTRATIVE EXAMPLE ON GEOPOLYMER
CONCRETE MIX DESIGN:
DESIGN STIPULATIONS
a) Characteristic compressive = 30 Mpa
at the temperature of 60ºC for about 36 hours
b) Maximum size of aggregate = 10 mm (angular)
c) Specific gravity of Fly ash = 2.3
d) Specific gravity of coarse aggregate = 2.6
e) Specific gravity of fine aggregate = 2.71 (river Sand)
(River Sand or Msand)
f) Sand conforming = zone III
g) Specific gravity of NaOH = 1.47
h) Specific gravity of Na2sio3 = 1.6
38. 1) Selection of Fly ash to the compressive ratio:
The amount of flyash required for M30 grade =550 Kg/m3 is Derived from
the above Fig:1.
39. 2) Selection of Alkaline liquid ratio:
0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0 5 10 15 20 25 30 35 40
Alkaline
liquid
to
flyash
ratio
Compressive Stress N/mm2
Alkaline liquid to flyash ratio and Compressive
stress of concrete
River Sand
M-Sand
40. Compressive
Stress
Sodium
Hydroxide
Sodium
silicate
10 1 3
15 1 2.5
20 1 2.5
25 1 2.5
30 1 2.5
35 1 2.5
40 1 2.5
45 1 2.5
The ratio between Sodium hydroxide to sodium silicate is 1:2.5 From the table
above
The amount of alkaline liquid required accordance to compressive stress from the
above slide.
The amount of Alkaline liquid = 0.59 x flyash content =0.59x550 = 324.5 Kg/m3
Amount of Sodium silicate Solution = 231.79 Kg/m3
Amount of Sodium Hydroxide Solution = 92.71 Kg/m3
41. Morality to be used in the concrete is 16 molar in which 444 grams
of NaOH solids dissolved in 556 grams of water. From the reference
of B V Rangan document
Solids = 41.17 Kg/m3
Water = 51.55 Kg/m3
3) Selection of Water content.
The Maximum water content to add extra is 0.06 Water to flyash ratio
The Minimum Water content to be added extra is 0.02 water to flyash ratio
According to workability extra water can be added this is due to Flyash is
arrived from various plant which have different properties in absorption of
water in order to match extra water is added.
Amount of water add extra 0.02 to water flyash ratio = 0.02x525 = 11
Kg/m3
42. 4) Adjustment of values in sand content percentage.
Approximate sand contents per cubic metre of concrete for grades up
to M35grade
Nominal size of Coarse
aggregate
Sand as percentage of total
aggregate by absolute volume
10mm 40
20mm 35
43. Change in condition Sand content in %
For Sand conforming to Zone III -1.5%
For Decrease in sand content -2.5%
Total -4.0%
From above graph decrease in sand content = 4.0%
Total aggregate by absolute volume =(40 – 4.0) = 36.0%
Change in condition Sand content in%
For Sand conforming to
Zone I +1.5%
Zone III -1.5%
Zone IV -3.0%
The Change Condition Of Sand
44. Nominal Maximum size of
aggregate in mm
Entrapped Air as percentage of volume of
concrete
10 3%
20 2%
5) Estimation of Air Content
Approximate air content
45. 6) Determination of aggregate content:
Where,
V = absolute volume of fresh concrete, which is equal to
gross volume minus the volume of entrapped air.
S = Sodium Silicate Solution (kg) per m3 of concrete.
SO = Sodium Hydroxide Solution (kg) per m3 of concrete
F = Weight of cement (kg) per of Flyash
SF = specific gravity of Flyash
p = ratio of fine aggregate to total aggregate by absolute
volume
46. Fa, Ca = Total masses of fine aggregate and coarse
aggregate (kg) per of concrete respectively
SFa, SCa = Specific gravity of saturated surface dry fine
aggregate and coarse aggregate respectively.
SF = Specific gravity of Sodium silicate solution.
So = Specific gravity of Sodium hydroxide solution.
Fine aggregate content:
0.97 = {(92.7/1.47) + (231.8/1.6) + (550.0/2.3) + (1/0.36) (Fa/2.71)}x(1/1000)
Fa = 510.2 Kg/m3
Coarse aggregate content:
0.97 = {(92.7/1.47) + (231.8/1.6) + (550.0/2.3) + (1/ (1-0.36)) (Ca/2.6)} x(1/1000)
Ca = 870.2 Kg/m3
59. RESULT AND DISCUSSION On Geopolymer
concrete
FLY ASH
The compressive strength of concrete was improved with the increase in the fly
ash content.
ALKALINE LIQUID
The workability of the mixes increased with the increase in the alkaline liquid /
Fly ash ratio.
Geopolymer Concrete is in form of sticky due to the presence of sodium silicate
as a gel form.
Setting time of the concrete takes long period in ambient condition due to the
presence of the sodium silicate in gel form so the heat curing is recommended
Due to the polymerization reaction the hardened concrete will get higher
compressive strength on decrease in moisture content at the initial stage.
60. From the investigation the concrete was very stiff with no flow value at
the liquid alkaline/ash ratio of 0.33. The concrete was not homogenous
and difficult to mix and compact with the liquid alkaline/ ash ratio of
0.43. The workable concrete was obtained with the liquid alkaline/ash
ratios of 0.597 and 0.709, respectively.
Sodium silicate/NaOH ratio
In this test, the liquid Sodium silicate / NaOH ratio was kept constant at
1:2.5 and 1:3.
EXTRA WATER/FLY ASH RATIO
The effects of water/Fly ash ratios are expected to improve the
workability of geopolymer concrete.
From the analysis the extra water which we had recommended will not
affect the Characteristic Compressive Strength majorly.
61. RIVER SAND TO M-SAND:
Water absorption of the M-Sand is higher than that of river sand. In
order to overcome surface dry saturated to be done on M-sand.
Since M-sand absorb water content in the alkaline liquid Extra water to
be add as mentioned in the mix design.
M-sands workability is less when compare to the river Sand Mix.
For M-sand, From the Experimental study when compare to river sand
the alkaline liquid is little bit higher.
Tensile strength of the river sand is high when compare to the M-sand.
62. REFERENCES
Bakharev, T. (2005a). Durability of geopolymer materials in sodium and
magnesium sulphate solutions. Cement And Concrete Research, 35(6), 1233-
246.
Bakharev, T. (2005b). Geopolymeric materials prepared using Class F fly ash
and elevated temperature curing. Cement And Concrete Research, 35(6), 224-
1232.
The World Wide Web: www.geopolymer.org
B V Rangan (2002). Development and properties of low-calcium fly ash-based
geopolymer concrete.
B V Rangan (2008). Fly ash-based geopolymer concrete
Li, G., & Zhao, X. (2003). Properties of concrete incorporating fly ash and ground
granulated blast-furnace slag. Cement & Concrete Composites, 25(3), 293- 299.
