Geopolymer concrete is an innovative and eco-friendly alternative to traditional cement concrete, utilizing materials like fly ash and alkali solutions instead of cement, thereby reducing carbon dioxide emissions. It exhibits superior properties such as high compressive strength, low creep, and durability, making it suitable for various applications including precast products, pavements, and water tanks. While there are advantages like chemical resistance and fireproofing, challenges such as high costs and handling issues remain, necessitating further research and wider acceptance in the construction industry.

1. PHYSICAL PROPERTIES AND
APPLICATIONS OF
GEOPOLYMER CONCRETE

2. CONTENTS
• Introduction
• Why not OPC?
• OPC usage without environmental impact
• Why geopolymer concrete?
• Constituents
• Process and Mechanism
• Types of GPC
• Test on GPC
• Properties
• Applications
• Advantages and disadvantages
• Discussion on future development
• Conclusion

3. INTRODUCTION
• Geopolymer concrete is an innovative, eco-friendly
construction material.
• It is used as replacement of cement concrete.
• In geopolymer concrete cement is not used as a binding
material.
• Fly ash, silica-fume, or GGBS, along with alkali solution
are used as binders.
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4. FIGURE 1-GEOPOLYMER CONCRETE
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5. WHY NOT OPC?
• It is the most consumed commodity in the world after
water.
• It is also the most energy intensive material
• Cement production leads to high carbon-dioxide emission.
- 1 ton of CO2 is produced for every 1 ton of cement.
-It is produced by calcination of limestone and burning of
fossil fuels
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6. IS THERE A WAY TO USE OPC WITHOUT
ENVIRONMENTAL IMPACT?
-replacing some limestone with fly ash and blast furnace
slag called as blended cement
-using carbon dioxide emission captures and storage(CCS)
-accelerated carbonation where CO2 penetrate concrete
reacting with Ca(OH)2 in presence of H2O forming CaCO3
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7. WHY GEOPOLYMER CONCRETE?
• Reduces the demand of OPC which leads CO2 emission.
• Utilise waste materials from industries such as fly ash,
silica-fume, GGBS.
• Protect water bodies from contamination due to fly ash
disposal.
• Conserve acres of land that would have been used for coal
combustion products disposal.
• Produce a more durable infrastructure.
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8. CONSTITUENTS
• Coarse aggregate
• Fine aggregate - sand or bottom ash can be used
• Admixture - superplasticizers(naphthalene based or
naphthalene sulphonate based)
• Alkaline activators
-Alkaline activation is a process of mixing powdery
aluminosilicate with an alkaline activator .
-It produce a paste which sets and hardens within short duration
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9. -Alkaline activators commonly used are sodium or potassium
hydroxide.
-They are used in combination with sodium silicate(water
glass) or potassium silicate solution.
-NaOH and Na2SiO3 are more commonly used as it leads to
higher geopolymerisation rate.
-K2SiO3 solution rarely used because of high cost and lack of
easy availability.
-Alkali hydroxide is used for dissolution and sodium-silicate
solution as binder.
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10.  Sodium hydroxide
- dissolved in water to form a semi-solid paste
-higher amount reduces ettringite
-makes crystalline product which is stable in aggressive
environment
 Potassium hydroxide
-improve porosity and compressive strength
 Sodium silicate(water glass)
-available in gel form
-for good pozzolanic reaction it is mixed with NaOH
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11. • Fly ash
-combustion by-product of coal in coal fired power plants
-two classes of fly ash are F and C
TABLE1:CHEMICAL COMPOSITION OF FLY ASH
OXIDES PERCENTAGE
SiO2 52
Al2O3 33.9
Fe2O3 4
CaO 1.2
K2O 0.83
Na2O 0.27
MgO 0.81
SO3 0.28
LOI 6.23
SiO2/Al2O3 1.5 9

12. -fly ash used in concrete to increase life cycle expectancy
-helps in increasing durability
-improves permeability by lowering water-cement ratio
-spherical shape of fly ash improves consolidation of
concrete
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13. • GGBS
-a mineral admixture of silicates and aluminates of Ca and
other bases
- same main chemical constituents as OPC but in different
proportions
- improves compressive strength of GPC
TABLE 2-CHEMICAL COMPOSITION OF GGBS
CEMICAL
CONSTITUTION
CEMENT(%) GGBS(%)
Calcium oxide 65 40
Silicon dioxide 20 35
Aluminium oxide 5 10
Magnesium oxide 2 8
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14. • Silica fume
-also called as micro silica or condensed silica fume
-produced during manufacture of silicon by electric arc
furnace
-another artificial pozzolan
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15. • PROCESS
-Si and Al atoms in source materials dissolved using
alkaline solution.
-Source materials include fly ash ,GGBS, silica-fume.
- gel formed by applying heat.
-This gel binds aggregates and unreacted source material
forming geopolymer concrete
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16. • MECHANISM
-dissolution of Si and Al atoms takes place through the
action of OH ions
-precursor ions condense to form monomers
-polycondensation of monomers to form polymeric
structures
-this framework formed is called as polysilates
-silate stands for silicon-oxo-aluminate building unit
-chains and rings formed and cross linked through
Si-O-Al bridge
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17. TYPES OF GEOPOLYMER
 Slag based geopolymer
-Slag is a mixture of metal oxides and silicon dioxide
- a transparent by-product material formed in the processing
of melting iron ore.
-OPC replacement with slag improve workability and reduce
lifecycle costs
-it also increase its compressive strength
-corex slag, steel slag, iron blast furnace slag are examples
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18.  Rock based geopolymer
-MK-750 in the slag based geopolymer replaced by natural
rock forming minerals forms this geopolymer
-feldspar and quartz are natural rock forming minerals
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19.  Fly ash based geopolymer
- improves workability and increase compressive strength
-reduce cost of OPC along with CO2 emission
-reduce drying shrinkage
-class F fly ash used commonly
Alkali activated geopolymer: Heat curing at 60 to 80 οC
is done. Into 1:2 aluminosilicate gel fly ash particles are
embedded.
Slag based geopolymer:It contains silicate, blast
furnace slag and fly ash
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20.  Ferro-silicate based geopolymer
-same properties as that of rock based geopolymers
-has a red colour
-high iron oxide content
-poly type geopolymer formed by substituting some of the
aluminium atoms in the matrix
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21. TEST ON GPC
• CREEP TEST
-three 150x300 mm cylinders prepared
- placed on creep testing frame with hydraulic loading
system
-before loading 7th day compressive strength determined
-load corresponding to 40% of mean compressive strength
applied
-strain values measured and recorded
-test conducted at 23οC and relative humidity 40-60%
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22. • creep of GPC smaller than that of OPC
• smaller creep due to block polymerisation concept
• presence of micro-aggregates increase creep resisting
function in GPC
• in OPC creep caused by cement paste
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23. • DRYING SHRINKAGE TEST
-75x75x285 mm prisms with gauge studs used
-specimens kept in a controlled temperature environment
-temperature at 23οC and relative humidity 40-60%
-shrinkage strain measurements taken on third day of
casting concrete
-specimen demoulded and 1st measurement taken
-horizontal length comparator used for measurement
-next measurement taken on 4th day
-further measurements taken till one year
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24. • drying shrinkage of GPC is very less
• ambient temperature cured GPC shows more shrinkage
than heat cured GPC
• excess water evaporates during heat curing reducing dry
shrinkage
• drying shrinkage of GPC at ambient temperature is same
as that of OPC
• GPC undergoes shrinkage of 100 micro strains after one
year
• 500-800 micro strains experienced by OPC
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25. FIGURE 2 - DRYING SHRINKAGE OF HEAT CURED AND
AMBIENT CURED SPECIMEN
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26. • COMPRESSIVE STRENGTH
-higher compressive strength when heat activated
-slag addition improves compressive strength at ambient
temperature curing
FIGURE 3- COMPRESSIVE STRENGTH OF GEOPOLYMER CONCRETE
IN AMBIENT CONDITION
Time(days)
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27. • compressive strength of GPC decreased with increasing
fly ash content
• it increased with higher aggregate content
• higher strength at lower alkali content
• compressive strength increased with age
• Polycondensation of silica and alumina contribute to
high strength
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28. • MODULUS OF ELASTICITY AND POISSON’S RATIO
-modulus of elasticity increased with compressive strength
in OPC
-similar trend in GPC but values lower than OPC
-GPC cured at elevated temperature yields higher value of
E than cured at ambient temperature
-Poisson’s ratio of GPC similar to that of OPC and
increased with compressive strength
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29. TABLE 3 -YOUNG’S MODULUS AND POISSON’S RATIO
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30. 28

31. PROPERTIES
• Workability
-increase in NaOH and sodium silicate solution reduce flow
of mortar
-superplasticizer or extra water can be added to increase
workability
• Compressive strength
-it depends on curing time and temperature
-it increase with fly ash content
-it increase with fineness of fly ash
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32. • Resistance against aggressive environment
-used in constructing marine structures
-in OPC white layer of crystals formed on acid exposed
surface
-in GPC there is no gypsum deposition and no visible cracks
-a soft and powdery layer formed during early stages of
exposure which later becomes harder
-mass loss on exposure to H2SO4 in GPC was 3% and in OPC
20-25%
-higher the alkali content higher the weight loss
-GPC showed better resistance
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33. • Behaviour of geopolymer at elevated temperature
-high strength loss during early heating period(up to 200οC)
-beyond 600οC no further strength loss
-no visible cracks up to 600 οC
-minor cracks at 800 οC
-GPC with more compatability between aggregates and matrix
led to less strength loss
• Bond strength
-very high
-about one third of its compressive strength
-four times than that of OPC
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34. APPLICATIONS
• PAVEMENTS
-light pavements can be cast using GPC
-no bleed water rise to the surface
-aliphatic alcohol based spray used to provide protection against
drying
FIGURE 5 – PLACING OF PAVEMENT USING GEOPOLYMER CONCRETE
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35. • RETAINING WALL
-40MPa precast panels were used to build a retaining wall
-panels were 6m long and 2.4m wide
-these panels were cured under ambient condition
FIGURE 6 – PRECASTE GEOPOLYMER RETAINING WALLS FOR A PRIVATE RESIDENCE
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36. • WATER TANKS
-two water tanks were constructed, one with 32MPa concrete with
blended cement and other with GPC
-autogenous healing occurred in OPC due to calcium hydroxide
deposition
-in GPC tank there is little calcium hydroxide
-nominal leaking in tank healed rapidly due to gel swelling
mechanism
FIGURE 7 - INSITU WATER TANKS WITH BLENDED CONCRETE (LEFT)
AND GEOPOLYMER CONCRETE (RIGHT) 34

37. • BOAT RAMP
-approach slab on ground to ramp was made using geopolymer
reinforced with FFRP
-entire constituents remained dormant until activator chemicals were
added
FIGURE8 – BOAT RAMP CONSTRUCTED WITH BOTH IN-SITE AND PRECAST
GEOPOLYMER CONCRETE.
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38. • PRECAST BEAM
-GPC beams formed three suspended floor levels of GCI building
-beams had arched curved soffit
-water pipes were placed inside them for temperature controlled
hydronic heating of building spaces above and below
FIGURE 9 – GEOPOLYMER CONCRETE BEAM CRANED TO
POSITION
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39. ADVANTAGES
 high compressive strength
 high tensile strength
 low creep
 low drying shrinkage
 resistant to heat and cold
 chemically resistant
 highly durable
 fire proof
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40. DISADVANTAGES
 difficult to create
-requires special handling
-chemicals like sodium hydroxide are harmful to humans
-high cost of alkaline solution
 Pre-mix only
-sold only as pre-mix or pre-caste material
 Geopolymerisation process is sensitive
-lacks uniformity
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41. DISCUSSION ON FUTURE DEVELOPMENT
-more studies and wide scale acceptance for using GPC in
precast concrete products
-making GPC more user friendly by using lower amount
of alkaline solution
-producing more cost effective geopolymer
-replacing fine aggregate with quarry sand as demand for
natural sand is increasing
-studies on fibre reinforced geopolymer concrete for
improving flexural strength
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42. CONCLUSION
• Geopolymer concrete is a promising construction
material due to its low carbon dioxide emission
• High early strength, low creep and shrinkage, acid
resistance, fire resistance makes it better in usage than
OPC
• Wide spread applications in precast industries due to
-its high production in short duration
-less breakage during transportation
• Enhanced research along with acceptance required to
make it great advantage to the industry
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43. REFERENCES
• Aslani (2015); Thermal Performance Modelling of Geopolymer
Concrete, Journal of Materials in Civil Engineering
• Shankar H Sanni (2012); Performance of Geopolymer Concrete
under severe environmental conditions, International Journal on
Civil and Structural Engineering
• Ramujee et al (2014), Development of Low Calcium Fly
Ash Based Geopolymer Concrete, IACSIT International Journal
of Engineering and Technology, Volume 6
• Lloyd et al (2010);Geopolymer concrete: A review of
development and opportunities
• Bakharev, T., (2005(a)), Resistance of geopolymer materials to
acid attack, Cement and Concrete Research, 35, pp 658-670.
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