STRENGTH PROPERTIES ON FLY ASH BASED GEO POLYMER CONCRETE WITH ADMIXTURES

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International Journal of Civil Engineering and Technology (IJCIET) Volume 7, Issue 3, May–June 2016, pp. 347–353, Article ID: IJCIET_07_03_035 Available online at http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=7&IType=3 Journal Impact Factor (2016): 9.7820 (Calculated by GISI) www.jifactor.com ISSN Print: 0976-6308 and ISSN Online: 0976-6316

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STRENGTH PROPERTIES ON FLY ASH

BASED GEO POLYMER CONCRETE WITH

ADMIXTURES

A.Iftiqar Ahmed

PG Student, Department of Civil Engineering, Siddarth Institute of Engineering and Technology, Puttur, Andhra Pradesh, India.

Dr. S. Siddiraju

Professor and Head, Department of Civil Engineering, Siddarth Institute of Engineering and Technology, Puttur, Andhra Pradesh, India.

ABSTRACT

Due to increase in env ironmental problems of the construction industry

alternative technologies are emerging. A concrete is used around the world is second only to water. The making of ordinary Portland cement support 5 to 7 percent of total green house gas emission. It also takes large amount of energy

.Hence it is necessary to find alternative to cement .Fly ash is a product of coal procured from thermal power plant. It is also good in silicon and

alumina. In this experiment the fly ash is used to prepare the geo polymer concrete.geopolymer is a material resulting from the reaction of source materials that is rich in aluminum and silicon. One such material is

GEOPOLYMER CONCRETE. It uses a material like fly ash as binding material in place of cement. Here the alkaline solution, sodium silicate and

fly ash combine to form a gel which binds fine and coarse aggregates. Since geopolymer concrete is a new field, the guide lines from the BIS are yet to be created. A trail has been made to find out an optimum mix for fly ash

based geopolymer concrete. The size of concrete cubes 150X150X150 mm was casted. geopolymer concrete is free from cement. A grade chosen for the

investigation are M20.The mix are designed for molarity of 8M, 12M, 16M.we are calculated the slump values and compressive strength values. The compressive strength is found at 7 days and 28 days. By comparing the

geopolymer concrete with conventional concrete is more advantageous, economical and eco friendly.

Key word: Fly Ash, Geopolymer Concrete, Sodium Hydroxide (NaOH), Sodium Silicate (Na2SiO3), potassium hydroxide (KOH).

A.Iftiqar Ahmed and Dr.S.Siddiraju


Cite this Article: A.Iftiqar Ahmed and Dr.S.Siddiraju, Strength Properties on Fly Ash Based Geo Polymer Concrete with Admixtures International Journal

of Civil Engineering and Technology, 7(3), 2016, pp.352–358. http://www.iaeme.com/IJCIET/issues.asp?JType=IJCIET&VType=7&IType=3

1. INTRODUCTION

The alkaline liquid reacts with the silicon (Si) and the aluminum (Al) in by-product materials such as fly ash to produce binders. The chemical reaction that takes place in

this case is a polymerization. Geopolymer concrete is concrete which does not require any Portland cement in its making. The two main constituents of geo polymers are the

source materials and the alkaline liquids. The materials used for geo polymers lies on alumina-silicate rich in silicon (Si) and aluminium (Al). Alternatively, by-product materials such as fly ash, silica fume, slag, red mud, etc could be used as source

materials. Liquids are from soluble alkali metals that are usually sodium or potassium based. The alkaline liquid used in polymerisation is a mixture of sodium hydroxide

(NaOH) or potassium hydroxide (KOH) and sodium silicate.

2. MATERIALS USED

2.1. Fly Ash

The Fly ash is residue resulting from the burning of ground or powdered coal, which

is taken from the boiler by flue gases. Fly ash can be used in Portland cement concrete to increase the performance of the concrete. Fly ash is one of the remains

generated in burning, and contains the fine particles that flow with the flue gases.

Figure1: Fly Ash

Strength Properties on Fly Ash Based Geo Polymer Concrete with Admixtures


2.2. Coarse Aggregate

Coarse aggregate are an inert materials used in construction. Hard stones are crushed in required sizes. The material that is retained on IS sieve of size 4.75 is called coarse

aggregate. These aggregates combine with cement and fine aggregates with water to form concrete. Coarse aggregates of sizes 10mm and 20mm are used in this study.

The properties of coarse aggregate as shown in Table 1d

Table 1 Properties of Coarse Aggregate Aggregates

Property Coarse Aggregate

20mm

Coarse Aggregate

10mm

Fineness modulus 8.12 8.12

Specific Gravity 2.71 2.71

Bulk Density 1533.30

Kg/m3

1512

Kg/m3

Percentage of voids 44.15% 47.42%

2.3. Fine Aggregate

Fine aggregate is one which passes through IS sieve 4.75mm sieve and retained on 75 microns. It should not be soft; it should be free from organic matter and clean. Fine aggregate should not contain clay balls, alkalis, salts, coal, and decayed material. The

silt contents should be below 4%. The properties of fine aggregate are shown in Table 2.

Table 2 Properties of Fine aggregates:

Property Fine Aggregate

Fineness modulus 3.40

Specific gravity 2.61

Bulk Density 1250 kg/m3

Percentage of voids 51.24%

2.4 Sodium Hydroxide Solution

The alkaline activator used in geo polymerisation is a mixture of sodium hydroxide and sodium silicate. The alkali percentage is a significant factor in controlling the

leakage of alumina and silica from fly ash particles, following geo polymerization and mechanical properties of hardened geopolymer. The gel composition calculated in the sample animate with the mixture of sodium silicate and NaOH is increased in Na and

Al [1].

This solution is having of solute and solvent. Solute is the immerged substance

and solvent is the substance in which the solute is dessolved.A solute can be liquid or solid. In NaoH solution sodium hydroxide is the solute that is in solid state and water is the solvent that is liquid form. Notice that solute being a solid and is calculated in

terms of weight in (grams) .And the solvent water is denoted interms of volume.



Figure 2: Sodium Hydroxide flakes

2.5 Sodium Silicate Solution

Open porosity can be drawn and is readily filled with gel as soon as the liquid phase is able to mix with the ash particles. The liquid phase is vital as a fluid transport

medium allowing the activator to reach and act with the fly ash particles.

3. METHODOLOGY

3.1. Preparation of Alkaline Solution

In this experiment the compressive strength of geopolymer concrete is examined for

the mixes of varying molarities of Sodium hydroxide (8M, 12M, and 16M). The molecular weight of sodium hydroxide is 40. To prepare 8M i.e. 3 molar sodium

hydroxide solutions, 120g of sodium hydroxide flakes are weighed and they can be dissolved in dissolved in distilled water to form 1 litre solution. For this, volumetric flask of 1 litre capacity is taken, sodium hydroxide flakes are added slowly to distilled

water to prepare 1liter solution. The weights to be added to get required molarity are given in Table 2.

Table 3 Weights of NaoH Flakes

Required Molarity Weights in gms of

Sodium hydroxide flakes

8M 350

12M 520

16M 640



3.2. Proportioning of Geo-Polymer Concrete

The fly ash, fine aggregates and coarse aggregates are mixed in a container and then

the alkaline solution was added to prepare the geopolymer concrete. The geopolymer concrete is poured in 100 mm cube moulds. The Geopolymer concrete is in dark

colour with shiny appearance. The proportions of mixing are as given in Table 3. As per no code provisions for the mix design of geopolymer concrete, the density of geo-polymer concrete is assumed as 2440 kg/m3. The other values are found by

assuming the density of concrete.

The aggregate takes place the volume is assumed to be 65%. The quantities of all

ingredients are kept constant as given below Table 3 except the molarity of NaOH is changed in the each mix. The other method used in the making of normal concrete is included to prepare geopolymer concrete. First, the fine aggregate, coarse aggregate

and fly ash are mixed in dry condition for 3-4 minutes and after that the alkaline solution which is an addition of Sodium hydroxide solution and Sodium silicate

solution with super plasticizer is mixed to the dry mix.

The mixing is prepared about 6to8 minutes for correct bonding of the materials. After the mixing is done, the cubes are casted by providing with good compaction.

The size of the cube which is taken is of size 100*100*100 meters. the curing of geopolymer concrete cubes, the two methods are applied, one method is by kept the cubes

in hot air oven and by keeping the cubes in direct sunlight. In the oven curing, the cubes are removed and kept in oven at 60oc for an hour. Then the cubes are removed and kept in oven at 50oc for 7days. In the sun light curing, the cubes are removed after

1 day of casting and they are kept in the direct sunlight for 7 days. The mix Proportions of geo-polymer concrete as shown in Table 4

Table 4 Mixing Proportions of Geo-Polymer Concrete

Fly ash

Kg/m3

Fine

Aggregate

Kg/m3

Coarse

Aggregate

Kg/m3

NaOH

Solution

Kg/m3

Na2Sio3

Solution

Kg/m3

Extra

Water

Kg/m3

SP

Kg/m3

395.52 555.42 1294.5 46.12 113.65 40.65 12.85

3.3. Compressive Strength of Geo Polymer Concrete

The cubes are placed in compressive testing machine to found their compressive

strength to the age at 7 days of curing. The figure 3 and figure 4 are indicating the compressive strength develop with molarity of NaOH. (3M, 5M, 7M and 9M) for the specimens which are cured by hot air oven and by direct sun light at the age of 7days



Table 5 Compressive Strength of Geo Polymer Concrete

Specifications Avg. Ultimate load In kN

Avg.Compressive Strength in Mpa

FR M8 Cs A7 123.72 6.24

FR M8 Ch A7 363.25 17.25

FR M12 Cs A7 178.53 9.65

FR M12 C h A7 482.35 22.35

FR M16 Cs A7 196.25 9.65

FR M16 Ch A7 490.2 22.5

Figure 3 The Compressive Strength at Age of 7 days in Ambient Curing

Figure 4 Compressive Strength at Age of 7 days of Oven Cured

0

0.2

0.4

0.6

0.8

1

1.2

1.4

8M 12M 16M

7 days

Concentration of NaOH

Com

pre

ssiv

e S

tren

gth

, M

Pa

0

0.2

0.4

0.6

0.8

1

1.2

1.4

8M 12M 16M

7 days

Concentration of NaOH Com

pre

ssiv

e S

tren

gth

, M

Pa



4. CONCLUSIONS

We calculated that the compressive strength is increased with the Increase in the Molarity of sodium hydroxide.

For 7 days of curing the increased value in the compressive strength is significant.

Compare to hot air oven curing and curing by direct sun light, oven cured specimens gets more the compressive strength but sunlight curing is conveniently good for practical conditions.

REFERENCES

[1] Dody M.J. Sumajouw, Wallah, Studies on Fly Ash Based On Geo Polymer Concrete Geo Polymer: Green Concrete and Development Solutions.

[2] Shetty MS, The Concrete Technology Book, S. Chand Publishers.

[3] Strength and durability of fly ash based geopolymer concrete, Dr Chandra Shekhar Reddy , Final year dissertation, the Curtien University, Perth Australia

[4] Sameer Vyas, Neetu Singh, Rp Pathak, Pankaj Sharma, Nv Mahure and Sl Gupta, Behaviour of Alkali Activated Fly Ash-Based Geopolymer Concrete On Thermal Activation International Journal of Civil Engineering and Technology , 5(4), 2014, pp.28–36.

[5] Sameer Ul Bashir, Effect of Alkali Materials On Geo Polymer Concrete International Journal of Civil Engineering and Technology, 6(1), 2015, pp.1–13.

[6] Pateel Alekhya and Mr. S. Aravindan, Experimental Investigations on Geopolymer Concrete International Journal of Civil Engineering and Technology, 5(4), 2014, pp.1–9.

[7] T.V. Srinivas Murthy and Dr. Ajeet Kumar Rai, Geopolymer Concrete, An Earth Friendly Concrete, Very Promising In The Industry International Journal of Civil Engineering and Technology, 5(7), 2015, pp.113–122.