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EXPERIMENTAL INVESTIGATION OF HIGH STRENGTH

GEOPOLYMER CONCRETE

1 Dr. A. Anbuchezian, S. Vigneshwar2 3L. Balasuganya

1 Professor and Head in civil Engineering

2Assistant Professor in Civil Engineering

3Assistant professor in civil engineering

[email protected]@[email protected]

Abstract

This paper presents the experimental studies concerning high strength in geopolymer concrete. So far

many researches were carried out in geopolymer concrete and also it improves the strength and

durability than OPC concrete. Several constituents of GPC mixes were conducted by varying the

percentage of GGBS and Fly ash. By finding the optimum percentage in fly ash and GGBS from the

experimental results the properties of geopolymer concrete will be found out. From the optimum

percentage in fly ash and GGBS, steel fibres will be added to the geopolymer mix. The mechanical

properties of FRGPC and Conventional GPC will be compared. The study of flexural, Split tensile

and compression behavior of GPC and FRGPC concrete are going to be done with optimum 0.75% of

steel fibres and varying the Fly ash to GGBS ratio in 90:10, 80:20, 70:30 respectively and the results

are going to be compared with conventional high strength concrete and it is believed from the various

literatures that while increasing the GGBS ratio the geopolymer concrete will yield high strength.

Key words: Concrete, Geopolymer concrete, flyash, GGBS.

1. Introduction

Concrete is an important binding material and the use of concrete is driving responsible for the

massive production of cement. The cement industries are the reason for the global warming due to the

carbon dioxide emissions estimated to be responsible for 5 to 7% of the total global warming. Due to

enormous increase in infrastructure construction and industrialization conditions there is

inconsiderable increases in cement production have been observed. Utilization of industry waste

products, such as fly ash and slag, in place of cement is a potential alternative to reduce the carbon

footprint of the concrete industry without compromising performance. Geopolymers uses waste

products as the major constituents they contain no cement and behave in a same quasi-brittle fashion

to that of concrete members thus GPC emerging as a sustainable material. As the demand to construct

structures of greater complexity increases, so does the requirement for superior materials in terms of

robustness and durability. The use of fibres in reinforcement of concrete has been analysed more than

last five decades to withstand this demand. In addition to increasing the shear and tensile capacity of a

cementetious mix, the inclusion of fibres to a concrete matrix has been shown to enhance a number of

other material properties such as fatigue resistance, energy absorption and toughness, ductility,

durability and improves the service life of the material. By adding fibres in concrete mix propotion the

aim is to withstand discrete cracks resulting for some control in the fracture process.

Journal of Information and Computational Science

Volume 9 Issue 4 - 2019

ISSN: 1548-7741

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mailto:[email protected]



Geopolymer concrete:The term 'geopolymer' was first discovered by Davidovits in the year 1978 to

describe a pool of mineral binders with chemical composition similar to zeolites but with an

amorphous microstructure. After that in civil engineering profile professor applied the knowledge of

geopolymers and he founded the “geopolymer concrete” Polymers are either organic material that is

Carbon based polymer or silicon based inorganic polymer. The organic polymers comprises the

classes of natural polymers ,synthetic organic polymers and natural bio polymers .Raw materials used

in the developing of silicon based polymers are majorly of rock forming minerals in geological

origin, hence the name becomes geopolymer.

A geopolymer is essentially a mineral a mineral chemical compound or mixture of compound

consisting of repeating units , silico – oxide (-SI-O-SI-O-), silico aluminate (-SI-O-AL-O-), ferro-

silico-aluminate (-AL-O-SI-O-AL-O-), created through a process of geopolymerization. It makes use

of the polycondensation of high alkali content with alumina precursors and silica to attain structural

strength.The geopolymer concrete mainly consists of alkaline liquids and source materials. The source

materials should be high in silicon (Si) and aluminum (Al). The materials high in silicon and

aluminum are used as a source by product materials like fly ash, metakaoline,GGBS. Alkaline liquids

are form usually sodium based or potassium based.

2. Experimental program

I.Materials

In this chapter the materials used for this project is given. Fly ash and GGBS as a source materials,

alkaline liquids, super plasticizers, steel fibres, fine aggregates, coarse aggregates, and water are used

for the preparation of beams made by Fiber reinforced in geopolymer concrete beams (FRGC). And

the mix proportions for FRGC.

A. Fine aggregate

The aggregates passing through 3.75mm sieve is used as a fine aggregate. The properties of fine

aggregate is tested and conformed to IS: 383-1970.

Table1. Properties of fine aggregate

Properties Results

Specific

gravity 2.75

Bulk

density

1693

kg/m3

Fineness

modulus 2.75

B. Coarse aggregate:

A size of 12mm Coarse aggregates is used as a coarse aggregates and the coarse aggregates are

conformed to IS 2386- 1968.



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Table2. Properties of coarse aggregate

Properties Results

Specific

gravity 2.65

Bulk

density 1532kg/m3

Fineness

modulus 6.92

C. Fly ash:

Fly ash of class F is used for the preparation of FRGC.

Table3. Properties of fly ash

Properties Results

Bulk

density 1438kg/m3

Specific

gravity 2.3

Fineness 3.2

Moisture Nil

D. GGBS (ground granulated blast furnace slag)

To improve the setting time property of geopolymer concrete GGBS is added to the geopolymer mix.

E. Alkaline liquids

For the geopolymer concrete mix sodium hydroxide and sodium silicate solutions are used as an

alkaline liquids. When compared to potassium hydroxide and potassium silicate solutions sodium

based solution has low cost and also it creates the gel structures quickly. Sodium hydroxide is

available in pellets form and it’s purchased from local chemical industry. Sodium silicate is available

in liquid form and this sodium silicate also purchased from local chemical industry. Sodium

hydroxide pellets ate dissolved using distilled water in 10M and it’s made according to the

requirements.

Sodium hydroxide (NaOH)

Molecular weight of NaOH = 40

1M = 1 liter of distilled water X molecular weight

10M = 10 X 40

Amount of NaOH to be dissolved in 1 liter water = 400 grams.



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F.Super plasticizer

Conplast SP 430 which is brown in color and it is used as a super plasticizer in this project to improve

the setting and to reduce the water content. Super plasticizers are added with the extra water content

then mixed up with source materials to be mixed with concrete.

G. Steel fibres:

In this project hook end steel fibres are used in a particular volume Fraction of total volume of

Specimen and in a particular aspect ratios.

Table 4. Details of steel fibres

ID Length

(mm)

Diameter

(mm) Aspect ratio

Aspect ratio

1

35 0.75 45

This project utilizes hook end steel fibres it can also be replaced with carbon, glass and polypropylene

fibres also.

II. Mix proportion

Table 5. Mix ratio

MIX

ID

% of

steel

fibre

Fly

ash

Kg/𝑚3

GGBS

Kg/𝑚3

Fine

aggregate

Kg/𝑚3

Coarse

Aggregate

Kg/𝑚3

NAOH

Kg/𝑚3

N𝐴2SI𝑂3

Kg/𝑚3

Extra

water

Kg/𝑚3

Super

plasticizer

Kg/𝑚3

Steel

fibres

Kg/𝑚3

1 0.75 354.87 39.43 554.4 1293.4 45.1 112.6 59.14 11.83 19.63

2 0.75 315.44 78.86 554.4 1293.4 45.1 112.6 59.14 11.83 19.63

3 0.75 276.01 118.29 554.4 1293.4 45.1 112.6 59.14 11.83 19.63



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3. Test procedure

The test consists of casting and testing of 3 cubes and 3 cylinders in each respective ratios.1beam

in each respective ratios. Size of the beams 100 X 150X 1200mm, out of which one is conventional

M40 grade reinforced cement concrete and three geopolymer concrete beams. The beams designed as

under reinforced section. It is reinforced with 2-10# at bottom, 2-10 # at top using 6 mm diameter

stirrups @ 150 mm c/c. The companion 3 cubes of each ratio (150 x 150 x 150 mm size) and

3cylinders of each ratio (150 x 300mm) are also cast along with the beams and tested. The test setup

is made for compressive, split tensile and flexure strength. The flexure setup test specimen is mounted

in a Beam testing frame of 500 KN capacity. The beams are simply supported over a span of

1200mm, and subjected to two point loads placed symmetrically on the span. The distance between

the loads is 333.33mm.Deflections are measured using dial gauges of 0.001 mm as least count, in the

midspan of the member under certain load points for observing the deflection. The readings in dial

guage are recorded at different loads.

Figure 1 Figure 2

Figure 3



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4. Test results

A. Compressive strength:

Compressive strength is carried out by taking the average of three cube specimens for each mix

proportions.

Table 6. Compressive strength

Mix ID Cube1 Cube2 Cube3 Average

strength

M40 48.56 49.32 48.72 48.86

90:10

34.56

33.95 34.28 34.26

80:20

43.54

42.96 42.41 42.97

70:30

48.44

47.76 47.65

47.95

Figure 4: Compressive strength



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B. Split tensile strength:

Split tensile strength is carried out by taking the average of three cylinder specimens for each mix

proportions.

Table 7. Split tensile strength

Mix ID Cylinder1 Cylinder2 Cylinder3 Average

strength

M40 4.52

4.75 4.36 4.54

90:10 3.54

3.21 3.37 3.37

80:20 3.93

4.23 4.15 4.12

70:30 4.66

4.22 4.31 4.39

Figure 6: Split tensile strength



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C. Flexural strength

Flexural strength is carried out by one specimen in each mix proportions.

Table 8. Flexural strength

Mix ID Flexural

strength

M40 4.8

90:10 3.24

80:20 4.18

70:30 4.17

Figure 4: Flexural strength

5. CONCLUSION:

As related with the experimental work the following results are brought:

Higher concentrations of G.G.B.S result

in higher strength of compression in GPC.

Mixing of G.G.B.S was tested up to 30%, where 70:10 flyash:GGBS ratio give equivalent

strength properties of M40 grade concrete.

There is no need of exposing GPC to higher temperature to attain higher strength if minimum

9% of fly ash is replaced by GGBS.



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Compressive strength, split tensile strength and flexural strength of geopolymer concrete

increases with increase in percentage of replacement of fly ash with GGBS in respective

90:10, 80:20, 70:30 ratios. Fly ash was replaced by GGBS up to

30% beyond that fast setting was observed.

80% of compressive strength was achieved in 14 days.

The density of geopolymer concrete was equal to that of OPC concrete in average.

6. REFERENCES:

• Duxson P, Fernández-Jiménez A, Provis JL, Lukey GC, Palomo A, van Deventer JSJ.

Geopolymer technology: the current state of the art. J Mater Sci 2007;42(9):2917–33

• Roy DM, Idorn GM. Hydration, structure, and properties of blast-furnace slag cements,

mortars, and concrete. J American Concrete Inst 1982;79(6):444–57

• Davidovits J. High alkali cements for 21st century concretes, concrete technology, past,

present, and future. In: Mehta PK, editor. American Concrete Institute; 1994.

• Kumar S, Kumar R, Alex TC, Bandopadhyay A, Mehrotra SP. Effect ofmechanically activated

fly ash on the properties of geopolymer cement. Davidovits J. editor. Proceedings of the

world congress geopolymer; 2005.



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