An experimental investigation on properties of ggbs based geopolymer concrete for high volume traffic

IJRET: International Journal of Research in Engineering and Technology eISSN: 2319-1163 | pISSN: 2321-7308
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Volume: 03 Special Issue: 06 | May-2014 | RRDCE - 2014, Available @ http://www.ijret.org 313
AN EXPERIMENTAL INVESTIGATION ON PROPERTIES OF GGBS
BASED GEOPOLYMER CONCRETE FOR HIGH VOLUME TRAFFIC
Ravi Kumar R1
, Sridhar R2
1
Assistant Professor, Department of civil Engineering, Shri Madhwa Vadiraja Institute of Technology and Management,
Udupi
2
Research Scholar, Ghousia college of Engg &Assoc. professor, Department of civil Engg, Alva’s Institute of Engg &
Technology, Moodbidri, Karnataka, India
Abstract
The Civil Engineering construction is progressing massively day by day with the increase in demand for the cement production. One
ton production of cement emits about one ton of Carbon di Oxide into the atmosphere, including for burning of the fuel fossils and for
process of production using raw materials. This enormous liberation of Carbon di Oxide from the cement industries is one of the
major issues for the cause of ecological imbalance, resulting in green house effect. This emission of carbon di oxide into the
atmosphere is minimized by using the industrial by products or industrial wastes (binders) generated from the Steel Plants, called as
Ground Granulated Blast Furnace Slag (GGBS) and adding GGBS with the Sodium Hydroxide Solution and Sodium Silicate
Solutions, (together called as alkaline activators), which forms a good bond between the GGBS and other body forming inert
aggregates (Coarse and Fine Aggregates), without using the Ordinary Portland Cement. This new product branded as Geo-Polymer
Concrete, which addresses the solution to ecological issues and forms alternate construction material in the Civil Engineering
industry.
In the present work, an attempt has been made to establish the mix proportion to Geopolymer Concrete, to study the Engineering
Properties of Geopolymer Concrete and to prove that the new alternate material is ecofriendly. The mix combinations of alkaline
solutions are achieved by adding NaOH solution of varied molarity 12M, 14M and 16M, with the Sodium Silicate Solution
maintaining a ratio (Sodium Silicate to NaOH) of 2.5, 5.0 & 7.5 with the alkaline liquid to binder ratio as 0.3, 0.4 and 0.5. The
alkaline activator solutions are prepared 24 to 30 hrs in advance to mixing with the dry materials. The conventional method of
mixing, compacting and moulding is followed for the production of the Geopolymer concrete.
The Cubes, Cylinders and Beams are cast using the mould conforming to BIS Codal provisions. The appropriate measurement of
alkaline solutions is mixed with the calculated ingredients like GGBS and other inert materials, with proper compaction, the
specimens are prepared. The specimens thus made are cured for 24 hrs. in the ambient temperature, covering the entire specimens
with High Density Polyethylene Sheet in order to avoid the escape of the water from the green mix. Later the specimens in the mould
are kept at elevated temperature of 120°
C for another 24 hrs in the dry oven for further curing. The engineering properties namely,
Compressive Strength, Flexural Strength and Splitting Tensile Strength on Geopolymer Concrete specimens are studied and compared
the properties with the Ordinary Portland Cement Concrete. The results showed that geopolymer concrete exhibited encouraging
results compared to Ordinary Portland Cement Concrete (Compressive Strength= 50 MPa, Flexural Strength= 4.5 MPa & Splitting
Tensile Strength= 3.5 MPa) and Cost analysis indicated that Geopolymer concrete Costs 18% more than the Ordinary Portland
Cement Concrete satisfying all the engineering properties. Thus, Geopolymer Concrete, contains no Ordinary Portland Cement, is an
ecofriendly construction material, to make use in the various construction activities including the structural elements required for
pavements.
Keywords: Geopolymer Concrete, Ground Granulated Blast Furnace Slag (GGBS), alkaline liquid, Sodium Silicate
Solution.
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1. INTRODUCTION
In the present scenario, environmental pollution is the biggest
menace to the human race on this planet causing ecological
imbalance. There are many reasons which cause pollution. In
the construction industry, cement is the main ingredient/
material for the concrete production. The production of
cement involves the emission of carbon di oxide during its
production. There are two different sources of carbon di oxide
emission during cement production. Combustion of fossil
fuels to operate the rotary kiln is the largest source and other

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one is the chemical process of calcining limestone into lime in
the cement kiln also produces carbon di oxide. In India about
2,069,738 thousands of metric tons of carbon di oxide is
emitted in the year of 2010. The cement industry contributes
about 5% of total global carbon dioxide emissions. The
cement is manufactured by using the raw materials such as
lime stone, clay and other minerals by procuring them by
quarrying process which also causes environmental
degradation. To produce 1 ton of cement, about 1.6 tons of
raw materials are required and the time taken to form the lime
stone is much longer than the rate at which humans use it.
On the other side, the demand of concrete is increasing day by
day for its ease of preparing and fabricating in all sorts of
convenient shapes. So to overcome this problem, the concrete
to be used should be environmental friendly. To produce
environmental friendly concrete, it is necessary to replace the
cement with the industrial by products such as fly-ash, GGBS
(Ground granulated blast furnace slag) etc. with new binding
activator to form a new product called “Geo Polymer
Concrete”.
The term geopolymer was first coined by Davidovits in 1978
to represent a broad range of materials characterized by chains
or networks of inorganic molecules. Geopolymers are chains
or networks of mineral molecules linked with co-valent bonds.
Geopolymer is produced by a polymeric reaction of alkaline
liquid with source material of geological origin or by product
material such as GGBS. Geo-polymers have the chemical
composition similar to Zeolites but they can be formed an
amorphous structure. For binding of materials the silica and
the alumina present in the source material are induced by
alkaline activators. The most common alkaline liquid used in
the geo-polymerization is the combination of Sodium
hydroxide and Sodium silicate. This combination increases the
rate of reaction. Among fifteen Alumino-silicate minerals, all
the Al-Si minerals are more soluble in sodium hydroxide
solution than in potassium hydroxide solution. Ground
granulated blast furnace slag (GGBS) is a by-product from the
blast-furnaces used to make iron. During the process, slag was
formed and it is then dried and ground to a fine powder.
2. LITERATURE REVIEW
2.1 History of Geopolymers
Davidovits coined the term geopolymer in 1978 to represent a
broad range of materials characterised by chains or networks
of inorganic molecules [Davidovits, 1979, 1993, 2008][5]
, and
explained in many of his publications about the possibility of
GPs being used by Egyptians construction of pyramids, based
on microscopy, IR and NMR spectroscopy of sparse
specimens from ancient Egyptian constructions [Davidovits
and Morris, 1988; Davidovits, 1999][7]
.Demortier observed the
noticeable differences in porosities in the top and bottom
sections of pyramid blocks which were also subjected to X-ray
and NMR analyses to conclude that pyramids could be made
from „concreting‟ operations [Demortier, 2004]. Use of slurry
to form bearing courses of horizontal joints and vertical joints
between the blocks including presence of hair in the joints of
pyramids did indicate the possibility of „concrete‟ like
technology for pyramid constructions .
2.2 Fresh Geopolymer Concrete Mixes
Hardjito et al, (2002)[17]
observed that fresh geopolymer
concrete is highly viscous and cohesive with low workability
when the calcined kaolin was the source material.
2.3 Structural Usages
Davidovits and Sawyer (1985)[6]
used ground blast furnace
slag to produce geopolymer binders. This type of binders
patented in the USA under the title „Early High-Strength
Mineral Polymer‟, was used as a supplementary cementing
material in the production of precast concrete products.
2.4 Activating Medium
A combination of sodium or potassium silicate and sodium or
potassium hydroxide has been widely used as the alkaline
activator (Palomo et al, 1999; van Jaarsveld, van Deventer &
Lukey 2002; Xu & van Deventer, 2000; Swanepoel &
Strydom, 2002)[23,32]
, with the activator liquid-to-source
material ratio by mass in the range of 0.25-0.30 (Palomo,
Grutzeck & Blanco 1999; Swanepoel & Strydom 2002)[31]
.
Anurag Mishra (2008, 2009) conducted experiments on FA
based GPC by varying the concentration of NaOH and curing
time. Total nine mixes were prepared with NaOH
concentration as 8M, 12M, 16M and curing time as 24hrs,
48hrs, and 72hrs. The investigation indicated: an increase in
compressive strength with increase in NaOH concentration
and curing time, increase in compressive strength after 48hrs
curing time not significant. Compressive strength up to 46
MPa was obtained with curing at 60ºC. Water absorption
decreased with increase in NaOH concentration and curing
time.
3. SCOPE AND OBJECTIVES PRESENT WORK
3.1 Need for the Present Study
It is evident from the present facts that the production of
Ordinary Portland Cement is causing much of the
environmental hazards such as-
 Emission of green house gases.
 Enormous consumption of power for the manufacture
of cement.
 Minimize the waste of potable water in construction
industries.
As such, a new alternate binding material is necessary in order
to address the problems, resulting in development of
geopolymer concrete.

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3.2 Scope and Objectives of Present Study
The aim of this research is to evaluate the performance and
suitability of GGBS based geopolymer concrete as an
alternative to the use of Ordinary Portland Cement (OPC) in
the production of concrete.
The individual objectives will include:
 To evaluate the different strength properties of
geopolymer concrete mixture with GGBS.
 To make workable, high strength geopolymer
concrete containing GGBS without usage of Ordinary
Portland Cement.
 To find out effective utilisation of industrial by
product like GGBS.
 To develop an eco-friendly alternative binding
material.
4. MATERIALS
4.1 Materials Used for Conventional Concrete
 Cement
 Aggregates
 Water
4.2 Materials Used For GPC
The materials used for preparing GGBS based geopolymer
concrete specimens are,
 Ground Granulated Blast Furnace Slag (GGBS)
 Sodium hydroxide flakes
 Sodium silicate solution
 Fine aggregate
 Coarse aggregate
Fig: 4.1 Ground Granulated Blast Furnace Slag
The physical properties and chemical compositions of GGBS
are given in the table 4.1 and 4.2
Table 4.1: Physical Properties of GGBS
Sl.no Properties Values
1 Specific gravity 2.78
2 Fineness by 90µ sieve 6%
Table 4.2: Chemical Composition of GGBS
Sl no.
Chemical
composition
Mass %
1 C 16.82
2 O 37.06
3 Mg 2.56
4 Al 3.56
5 Si 4.95
6 Ca 26.75
7 Mn 2.25
8 Cu 6.05
4.3 Sodium Hydroxide
Generally the sodium hydroxides with purity of 98% available
in solid from by means of flakes were used for the present
investigation. The mass of water is the major component in
both the alkaline solutions. In order to improve the workability
extra water has been added to the mixture. In the present
investigation sodium hydroxide flakes were obtained from the
Travancore – Cochin Chemicals Limited through a local
dealer.
Fig: 4.2 Sodium Hydroxide Flakes

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4.4 Sodium Silicate Solution
Sodium silicate is also known as water glass or liquid glass,
available in liquid (gel) form. The sodium silicate solution is
commercially available in different grades. The sodium
silicate solution with SiO2 = 32.68%, Na2O = 15.63%, and
water = 51.69% by mass, has been used for the present study.
As per the manufacture, silicates were supplied to the
detergent company and textile industry as bonding agent.
Same sodium silicate is used for the making of geopolymer
concrete. In the present investigation sodium silicate solution
was purchased from local market.
Fig: 4.3 Sodium Silicate Solutions
5. MOLARITY CALCULATION
For 12 M NaOH calculation
NaOH solution with a concentration of 12 Molar consists of
12 x 40 = 480 grams of NaOH solids per litre of the water,
were 40 is the molecular weight of NaOH
Therefore,
0.480 kg of NaOH flakes in 1 kg of water
1.48 kg of mass of NaOH solution contains 0.480 kg of flakes
1.0 kg of mass of NaOH solution contains=1*0.48/1.48=
0.3243 kg flakes
1 kg of mass of NaOH solution contains 0.3243 kg NaOH
flakes
Table 5.1: Molarity Calculation
Molarity
NaOH flakes in
one lt of water
(kg)
NaOH flakes in
one lt of NaOH
solution (kg)
12M 0.480 0.3243
14M 0.560 0.359
16M 0.640 0.390
6. PREPARATION OF TEST SPECIMENS
6.1 Preparation of the Alkaline Solution
The Sodium hydroxide flakes were dissolved in water to make
the solution. The concentration of the NaOH solution depends
on the molarity; 12 M, 14 M, 16 M. The sodium silicate
solution was added to this NaOH solution and this mixture of
alkaline liquid was prepared one day prior to the casting of the
specimens as this is confirmed to have the better results
(Hardjito and Rangan)[18]
.The alkaline liquid was used after 24
hrs and within 36 hrs .(Hardjito and Rangan)[18]
. On the day of
casting of the specimens, the alkaline liquid was mixed to
binder and aggregates with water added (if necessary) in order
to achieve better workability.
6.2 Mixing, Casting and Curing of GPC
For mixing, conventional method used for making normal
concrete was adopted to prepare geopolymer concrete.The
solid constituents viz. GGBS and aggregates were mixed in
dry form for about 3-4 minutes. At the end of this mixing ,the
liquid component of the geopolymer concrete mixture
,i.e.,combination of the alkaline solution with extra water was
added to the solids and the mixing continued for another 3-4
minutes.The fresh GGBS based geopolymer concrete was grey
in colour and shiny in appearance. The green mix was
cohesive.The workability of the fresh concrete was measured
by means of the conventional slump test.
The fresh concrete was then poured into the moulds in three
layers immediately after mixing and compacted by hand
compaction by giving 25 strokes for each layer .After casting
the test specimens were covered with HDPE (High Density
Polyethelene) sheet, to minimise the water evoporation during
the rest period of 24hrs at room temperature. At the end of 24
hrs all the specimens along with the mould were placed inside
the hot air oven and cured at 120°c for another 24 hrs.
The specimens were taken out from the oven and kept to air-
dry at room temperature and after cooling to the room
temperature the specimens were de-moulded and tested to
determine the various strength properties.

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Fig 6.1: Fresh GGBS Based Geopolymer Concrete
Fig 6.2: Specimens Covered with High Density Polyethelene
Sheet
Fig 6.3: Specimens Along with Moulds
Fig 6.4: Specimens Kept for Curing
7. RESULTS
The effects of various salient parameters on the compressive
strength of geopolymer concrete are discussed. The
parameters considered are,
 Compressive strength v/s Binder.
 Compressive strength v/s Alkaline liquid ratio.
7.1 Compressive Strength v/s Binder
The different binder quantity added in the mixture is shown in
the table no.5.1.1for 12 M, 14M and 16M NaOH solutions and
study on compressive strengths was made. It is observed from
the figure 5.1.1 to5.1.4, that the compressive strength of
Geopolymer concrete specimen is more for 7.0 kg binder
rather than 6.5 kg and 7.5 kg binder (calculated for 5 cubes)
for alkaline liquid to binder ratio of 0.4. This result shows that
higher or lower quantity of the binder, yields lower value of
compressive strength. Similarly higher or lower ratio of
alkaline liquid to binder ratio also yields lower value of
compressive strength. A similar trend is same for different
molarities of NaOH solution.
This effect is due to the reaction with the alumina-silicates
present in the industrial waste and the alkaline activators
added in the optimum quantity shown above.
It is observed that higher value of compressive strength is
shown in 12M solution instead of 14M or 16M solutions. This
also prevails that higher molarity in NaOH does not help in
achieving the compressive strength. However better results are
shown in 12M solutions compared to higher molarity NaOH
solution.

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Fig 7.1: Effect on Compressive Strength by Binder
7.2 Compressive Strength v/s Alkaline Liquid Ratio
The different alkaline liquid ratio added to the mixture is
shown in the table no.5.2.1 for 12M, 14M, 16M NaOH
solution and study on compressive strength was made. It is
observed from the figure 5.2.1 to 5.2.4 that the compressive
strength of GPC specimens is more for Alkaline liquid to
binder ratio of 0.4.
It is also observed that as the ratio of Na2SiO3/NaOH increases
the compressive strength also increases. A similar approach is
same for different molarities of NaOH solution.
The reason for increase of compressive strength is due to
increase of solids (Silicate + NaOH).
Fig 7.5: Effect on Compressive Strength by Alkaline Liquid
Ratio

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Ratio
Ratio
Fig7.8: Effect of Compressive Strength by Alkaline Liquid
Ratio
8. CONCLUSIONS
Based on the present experimental investigations the following
conclusions are drawn.
 Higher concentration of sodium hydroxide in the
solution results in lower compressive strength of
GGBS based geopolymer concrete.
 The compressive strength of geopolymer concrete is
more for the higher ratio of sodium silicate to sodium
hydroxide solution by mass.
 The compressive strength is lower in case of higher
or lower ratio of alkaline liquid to binder.
 It is evident that more the alkaline liquid
concentration (NaOH + Na2SiO3) yields lower
compressive strength.
 The compressive strength increases with the
increased concentration of sodium silicate solution,
upto certain ratio.
 As water binder ratio increases the compressive
strength of GGBS based geopolymer concrete
decreases.
 There is marginal decrease in the density of GGBS
based geopolymer concrete compared to the
conventional OPC concrete.
 The fresh GGBS based geopolymer concrete hardens
at room temperature.
REFERENCES
[1] Barbosa, V. F. F., Mackenzie, K. J. D. and
Thaumaturgo, C., (2000), “Synthesis and
characterisation of materials based on inorganic
polymers of alumina and silica: sodium polysialate
polymers”, International Journal of Inorganic
Materials, 2, 309- 317
[2] Bhikshma, V., Koti Reddy, M. and Srinivas Rao, T.,
“An Experimental Investigation on Properties of
Geopolymer Concrete (No Cement Concrete)”, Vol.
13, No. 6 (2012).
[3] Cheng, T. W. and Chiu, J. P. (2003). “Fire-resistant
Geopolymer Produced by Granulated Blast Furnace
Slag” Minerals Engineering 16(3): 205-210.
[4] Chindaprasirt, P., Chareerat, T., Siricicatnanon, V.
(2007). “Workability and Strength of Coarse High
Calcium Fly Ash Geopolymer”. Cement Concrete
Compos., 29: 224-229.
[5] Davidovits, J. 1984. “Pyramids of Egypt Made of Man-
Made Stone, Myth or Fact?” Symposium on
Archaeometry 1984. Smithsonian Institution,
Washington, DC.
[6] Davidovits, J. et al., “Process for Obtaining
Geopolymeric Alumino-Silicate and Products Thus
Obtained”, US patent USA 5, 342(1994) 595.
[7] Davidovits, J. (1999). “Chemistry of Geopolymeric
Systems, Terminology. Geopolymer” 99 International
Conference, France.

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