Seventh Sense Research Group www.internationaljournalssrg.org Page 1 Experimental Study Of Fly Ash Based Geopolymer Concrete with Robo Sand V.V.S.S Chandra Sekhar 1 , K.Brahmani 1 , A.Rohit 1 , K.Mohan Krishna 1 , C.Ravi Kumar Reddy 2 1 UG Student, Civil Engineering, Kallam Haranadha Reddy Institute Of Technology(KHIT), Guntur,A.P,INDIA 2 Professor, Civil Engineering, Kallam Haranadha Reddy Institute Of Technology(KHIT), Guntur,A.P, INDIA Abstract-We know that concrete is the most widely required and used component in every construction. As concrete requirement reach the peak, so as cement. The use of Portland cement results in pollution to the environment due to the release of major pollutant carbon dioxide (CO2). As such, many alternate materials had been introduced to exchange cement in the concrete. Fly ash which is end- product from the coal industry is easily available material in the world. Also, usage of fly ash is more environment- friendly and economical compared to OPC. Fly being sufficiently rich in silicate and aluminate reacts with alkaline activators forming an alumino-silicate gel that causes good binding with the aggregate resulting in the production of good concrete. The compressive strength of concrete increases with increase in fineness of fly ash which leads to the decrease in permeability. Along with fly ash, metakaolin is used. Another main component in concrete is the fine aggregate (sand), replaced by robosand or manufactured sand which is easily available and results in good strength compared to normal sand. Chemicals, Sodium Silicate (Na2SiO3) and Sodium Hydroxide (NaOH) are used in preparing alkaline activators with a molarity of 12M. All the cube specimens of 150X150X150 mm are cast and cured by oven curing followed by open-air curing before testing. These specimens are tested at different ages of 7 & 28 days. Keywords: Geopolymerisation, fly ash, metakaolin, robosand, alkaline activators. I. INTRODUCTION The present era we can observe over usage of natural resources and environmental-friendly methods are being developed for effective management of natural resources which remain only 30% according to studies. As we all know constructions now a day reaching the sky with its advanced technologies. But the base component of concrete remains same forever and ever. As the requirement of concrete increases, cement requirement increases. But the amount of carbon dioxide produced during manufacturing cement is 0.93 tons for a ton of cement. Hence, definitely, an alternative material has to the used for an eco-friendly construction. So, In 1978 Davidovits proposed special concrete termed as "Geopolymer" which acts as a perfect alternative for ordinary concrete [1]. From this technology and known fact that fly-ash, which is an end product of thermal power plant abundantly. Tests have been made utilizing both geopolymer technology and fly-ash. Hardjito et al introduced the early work on fly-ash based polymer concrete [6]. As there is an increasing demand for high strength concrete, metakaolin came into existence which is becomes very reactive in excess of calcium hydroxide. High strengths can be achieved depending upon color and quality of metakaolin. Due to increase in construction practices demand for river sand has been increased, as well as cost. Use of robosand enhances the quality of concrete by reducing the permeability as it contains perfect gradation. So, it serves as the best alternative for river sand. Alkaline activators are the solutions that play major role in geo polymerization as they react with the aluminosilicates present in fly ash. II. LITERATURE REVIEW G.Himali Kumari, N.Vidya Sagar et.al studied the Strength characteristics of concrete by partially replacing fine aggregate with robo sand. The study is focused on evaluating workability and strength by incorporating robosand in proportions of 0%,50%,75% &100% for concrete grades M25 and M35.It has been confirmed that the strength resulted due to replacement is 8- 12% more than the similar mix with conventional concrete.[2] G. Hemanaag & SRK Prasad (2014) conducted a study on Geo-polymer concrete using Metakaolin, Fly ash replacing cement. In this study, experiments are conducted on fly ash and metakaolin based GPC with various molarities of alkaline liquids. The compressive strengths are compared for different proportions. It is observed that metakaolin based GPC attained higher strengths compared to fly ash based GPC. Also observed that molarity is directly proportional to compressive strength i.e. increase in molarity resulted in increase of compressive strength.[3] M.Muthuanand, Dr.G.Dhanalakshmi (2015) on their study on metakaolin based geopolymer concrete, came to conclusion
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Seventh Sense Research Group www.internationaljournalssrg.org Page 1
C.Ravi Kumar Reddy2 1UG Student, Civil Engineering, Kallam Haranadha Reddy Institute Of Technology(KHIT), Guntur,A.P,INDIA 2Professor, Civil Engineering, Kallam Haranadha Reddy Institute Of Technology(KHIT), Guntur,A.P, INDIA
Abstract-We know that concrete is the most widely required
and used component in every construction. As concrete
requirement reach the peak, so as cement. The use of
Portland cement results in pollution to the environment due
to the release of major pollutant carbon dioxide (CO2). As
such, many alternate materials had been introduced to
exchange cement in the concrete. Fly ash which is end-
product from the coal industry is easily available material in
the world. Also, usage of fly ash is more environment-
friendly and economical compared to OPC. Fly being
sufficiently rich in silicate and aluminate reacts with
alkaline activators forming an alumino-silicate gel that
causes good binding with the aggregate resulting in the
production of good concrete. The compressive strength of
concrete increases with increase in fineness of fly ash which
leads to the decrease in permeability. Along with fly ash,
metakaolin is used. Another main component in concrete is
the fine aggregate (sand), replaced by robosand or
manufactured sand which is easily available and results in
good strength compared to normal sand. Chemicals, Sodium
Silicate (Na2SiO3) and Sodium Hydroxide (NaOH) are used
in preparing alkaline activators with a molarity of 12M. All
the cube specimens of 150X150X150 mm are cast and
cured by oven curing followed by open-air curing before
testing. These specimens are tested at different ages of 7 &
28 days.
Keywords: Geopolymerisation, fly ash, metakaolin,
robosand, alkaline activators.
I. INTRODUCTION
The present era we can observe over usage of natural
resources and environmental-friendly methods are
being developed for effective management of natural
resources which remain only 30% according to
studies. As we all know constructions now a day
reaching the sky with its advanced technologies. But
the base component of concrete remains same forever
and ever. As the requirement of concrete increases,
cement requirement increases. But the amount of
carbon dioxide produced during manufacturing
cement is 0.93 tons for a ton of cement. Hence,
definitely, an alternative material has to the used for
an eco-friendly construction. So, In 1978 Davidovits
proposed special concrete termed as "Geopolymer"
which acts as a perfect alternative for ordinary
concrete [1]. From this technology and known fact
that fly-ash, which is an end product of thermal power
plant abundantly. Tests have been made utilizing both
geopolymer technology and fly-ash. Hardjito et al
introduced the early work on fly-ash based polymer
concrete [6]. As there is an increasing demand for
high strength concrete, metakaolin came into
existence which is becomes very reactive in excess of
calcium hydroxide. High strengths can be achieved
depending upon color and quality of metakaolin. Due
to increase in construction practices demand for river
sand has been increased, as well as cost. Use of
robosand enhances the quality of concrete by reducing
the permeability as it contains perfect gradation. So, it
serves as the best alternative for river sand. Alkaline
activators are the solutions that play major role in geo
polymerization as they react with the aluminosilicates
present in fly ash.
II. LITERATURE REVIEW
G.Himali Kumari, N.Vidya Sagar et.al
studied the Strength characteristics of
concrete by partially replacing fine aggregate
with robo sand. The study is focused on
evaluating workability and strength by
incorporating robosand in proportions of
0%,50%,75% &100% for concrete grades
M25 and M35.It has been confirmed that the
strength resulted due to replacement is 8-
12% more than the similar mix with
conventional concrete.[2]
G. Hemanaag & SRK Prasad (2014)
conducted a study on Geo-polymer concrete
using Metakaolin, Fly ash replacing cement.
In this study, experiments are conducted on
fly ash and metakaolin based GPC with
various molarities of alkaline liquids. The
compressive strengths are compared for
different proportions. It is observed that
metakaolin based GPC attained higher
strengths compared to fly ash based GPC.
Also observed that molarity is directly
proportional to compressive strength i.e.
increase in molarity resulted in increase of
compressive strength.[3]
M.Muthuanand, Dr.G.Dhanalakshmi (2015) on their study on metakaolin based geopolymer concrete, came to conclusion
Seventh Sense Research Group www.internationaljournalssrg.org Page 2
that the compressive capacity of concrete cubes gradually increases with the addition of 10% of metakaolin. Due to a good alkaline reaction between fly ash and metakaolin, mix with 70% fly-ash and 30% metakaolin shows good compressive strength. Also, the increase in metakaolin proportion results good compressive strength.[7]
Chunchu Bala Rama Krishna and M.Rama Krishna investigated compressive and flexural strengths for various combinations of fly ash and metakaolin with different molarities like 8M, 10M & 12M considering M30 grade concrete. Air dry curing is adopted. The results showed that there is a significant increase in strength when the molarity has increased. It is also found that the type of metakaolin used affected the strength of geopolymer concrete. Buff colored(Pink) Metakaolin has given higher strength, unlike white metakaolin.[4]
P.K.Jamdade & U.R.Kawde investigated the behavior of fly ash based geopolymer concrete at elevated temperature curing in an oven. The cubes cast are subjected to different curing temperatures i.e. 600C, 900C & 1200C. The observed results revealed that as curing temperature increases, compressive strength increases. But cubes cured at 600C attained greater compressive strength and cubes cured at 900C & 1200C has not shown a significant increase in the compressive strength.[5]
III. Materials
A. Coarse Aggregate
Coarse aggregates used in the study are crushed
stones of 20mm and 10mm size obtained from nearby
quarry site. As per IS 10262:2009,20mm aggregates
are taken 60% of total aggregate content and 10mm
aggregates are taken 40% of total content. The
specific gravity of coarse aggregate obtained is 2.69.
Figure No.1 Coarse Aggregates
B. Fine Aggregate
The fine aggregate adopted in the present study is
robosand. Robo sand or M-Sand is used as a
replacement of river sand. Robo sand is a purified
form of quarry dust and washed to remove the fine
rock dust to enhance the quality as per IS: 2386-
1975.It has proper gradation with particle size ranging
from 0-4.75mm. It is free from deleterious substances
which are likely to be present in the normal sand. It
makes the concrete cohesive with a low number of
voids due to perfect gradation. The specific gravity of
this robo sand obtained is 2.65 and fineness modulus
is 3.5
Figure No.2 Robo Sand
C. Flyash
It is a residue that is obtained from the combustion
of coal. They are in rich in silicates and alumina
which react with the alkaline activators to produce a
gel that can bind the constituents resulting in the geo
polymerization process. Fly ash is acquired from the
Thermal power plant, Vijayawada. The present is
carried out by using Class-F Fly ash. The fineness of
fly ash is 15%. The specific gravity of fly ash
obtained is 2.13.Bulk density of fly ash is 965 kg/m3
Figure No.3 Fly ash
D. Metakaolin
Metakaolin is obtained from the clay mineral
kaolin through calcination at 650-7500 c in an
externally fired rotatory kiln. It is a highly reactive
compound and pozzolanic in nature. It is available in
different forms such as white and buff colored. In the