COMPRESSIVE STRENGTH AND MODULUS OF ELASTICITY OF GEOPOLYMER CONCRETE WITH MANAJEMEN RISIKO KONTRAK ANTARA KONTRAKTOR DENGAN SUBKONTRAKTOR.

i

COMPRESSIVE STRENGTH AND MODULUS OF

ELASTICITY OF GEOPOLYMER CONCRETE WITH

METAKAOLIN AND SILICA FUME

Final Project Report

as one of requirement to obtain S1 degree from Universitas Atma Jaya Yogyakarta

By:

GARUDEA MARTHA HANDYANINGTYAS NPM: 111313777

INTERNATIONAL S1 PROGRAM

DEPARTMENT OF CIVIL ENGINEERING

FACULTY OF ENGINEERING

UNIVERSITAS ATMA JAYA YOGYAKARTA

YOGYAKARTA

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There is surely a future hope for you,

And your hope will not be cut off….

(Proverbs 23:18)

Truly I tell you, if you have faith as small as a mustard seed, you can

say to this mountain, ‘Move from here to there,’ and it will move.

Nothing will be impossible for you.

(Matthew 17:20)

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ACKNOWLEDGEMENTS

Thank you to my Lord Jesus, because of His blessings, the final project can be finished on time and without any serious problem. The purpose of the final project with the title "Compressive Strength and Modulus of Elasticity of Geopolymer Concrete with Metakaolin and Silica Fume" is to complete the requirement of undergraduate program (S-1) in Faculty ofInternational Civil Engineering Program, UniversitasAtma Jaya Yogyakarta.For the completion of this final project, I also would like to express my gratitude towards:

1. Dr. Ir. A.M. Ade Lisantono., M.Eng.as my advisor for his advice and counseling. His constant support and advice have been invaluable.

2. Prof. Ir. Yoyong Arfiadi, M.Eng., Ph.D as a Dean and an Examiner of my final project for his advice.

3. Anastasia Yunika, S.T., M. Eng. as Coordinator and Lecturer of International Civil Engineering who always care about me.

4. J. Januar Sudjati, ST., MT. as the head of Civil Engineering Department of UniversitasAtma Jaya Yogyakarta.

5. Ir. Pranawa Widagdo, MT as an examiner of my final project for his advice. 6. Angelina Eva Lianasari, ST, MT., for her advice, support and help in my final

project.

7. V. Sukaryantara as a staff of Construction Material Technology Laboratory who always supports me and helps me in a whole process of the research. 8. All the lecturers and staffs in the civil engineering program, especially the

International program and Construction Materials Laboratory.

9. My lovely parents; Mr.Johan S. and Mrs. OnengTyas D.E., Sandy, Putri and Pamungkas who always pray for me, support me and cheer me up.

10. Justi, Eka, Dhony, Pras, Dicky, Arnold chong, Sigit, Paul,Johan, Wira, and Halim who always give a support and help me in the process of the research. 11. Danila, Putri, Natalie, Eirene, Fiesta, Melisa, Agnes, Brenna,Tika, Arif,

Nicho, Fandy, Stephen, Jojo, Jimmy, Jerry, Erik, Okie, Eko, Agung, Fajar, Liki, Nathan, and Petrus who always give a support and suggestion for me, pray for me and always cheer me up.

12. All of my friends, seniors and juniors especially in the international civil engineering program.

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13. All of my friends in KA GKIN who always support me and pray for me.

I realize, this report may be flawed. Therefore I accept any form of suggestion for further improvement. Thank you

Yogyakarta, March 2015 Author

Garudea Martha Handyaningtyas (111313777)

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TABLE OF CONTENT

Title ………... i

Statement...……….. ii

Approval...………... iii

Motto………... v

Acknowledgement....………. vi

Table of Content………... viii

List of Table………...……….. xi

List of Figures...………... xii

List of Equation……… xiv

Abstract………..………. xv

CHAPTER I INTRODUCTION 1.1. General Background……… 1

1.2. Problem Statement……….…. 4

1.3. Problem Limitation……….…. 4

1.4. Objectives……….……... 5

1.5. Final Project Originality……….……. 6

CHAPTER II LITERATURE REVIEW 2.1. Theories………..……….. 7

2.2. Another Research to Compare…..………... 8

ix CHAPTER III BASIC THEORY

3.1. Geopolymer Concrete.………...….. 11

3.2. Metakaolin……… 13

3.2.1 Advantages of Metakaolin………. 14

3.2.2 Use of Metakaolin……….. 15

3.3. Silica Fume………..……….……… 15

3.4. Alkali Activator…………..……….……….… 16

3.5. Aggregate……….……… 17

3.6. Distilled Water……….. 19

3.7. Compressive Strength………... 19

3.8. Modulus of Elasticity……… 21

3.9. Slump Value………. 21

3.10. Workability………. 21

3.11. The Age of Concrete………... 23

CHAPTER IV RESEARCH METHODOLOGY 4.1. Research Methodology……..……….….. 24

4.2. Specification of Specimen……….……….….. 25

4.3. Research of Framework…….……….…. 25

4.4. Materials……...………..……….. 26

4.5. Tools………. 31

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4.6.1 Fine Aggregate……….. 44

4.6.2 Coarse Aggregate………... 48

4.7. Specimen Testing……….. 50

4.8. Slump Test……… 53

4.9. Curing Process………. 54

4.10. Compressive Strength and Modulus of Elasticity Tests……… 54

4.11. Schedule of the Final Project………. 54

CHAPTER V DISCUSSION 5.1. Result and Discussion of Material Investigation……….. 56

5.1.1 Investigate the Fine Aggregate to Obtain the Results……… 56

5.1.2 Investigate the Coarse Aggregate to Obtain the Results………… 59

5.2. Slump Test……… 61

5.3. Weight Density of Concrete………. 62

5.4. Compressive Strength of Concrete………... 65

5.5. Modulus Elasticity of Concrete……… 69

CHAPTER VI CONCLUSION AND SUGGESTION 6.1. Conclusion……… 72

6.2. Suggestion………. 73

REREFENCES....……… 75

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LIST OF TABLES

Table 4.1.The Amount of Specimens 51 Table 4.2.Schedule of the Research 55 Table 5.1. Relationship Between the Color of the Solution and Organic

Mater Content 56

Table 5.2.Investigation of Mud in the Sand 57 Table 5.3.Result of the Density and Observation Test of Fine Aggregate 58 Table 5.4. Investigation of Mud in the Coarse Aggregate 59 Table 5.5.Result of the Density and Observation Test of Coarse

Aggregate 60

Table 5.6.The Result of Slump Test at 14 days and 28 days 62 Table 5.7.Specification of Weight Density Concrete 62 Table 5.8.Average Weight Density in 14 Days 63 Table 5.9.Average Weight Density in 28 Days 64 Table 5.10.Compression Strength Test 65 Table 5.11.Composition of the Contents 67 Table 5.12.Compressive Strength of Lisantono and Hatmoko Research 68 Table 5.13.Compressive Strength of the Test 68 Table 5.14.Modulus of Elasticity Test 70 Table 5.15.Average of Modulus of Elasticity Test 70

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LIST OF FIGURES

Fig.3.1. Cylinder Sample 20

Fig.4.1. Flowchart of Research Framework 26

Fig.4.2. Fine Aggregate 26

Fig.4.3. Coarse Aggregate 27

Fig.4.4. Metakaolin 27

Fig.4.5. Silica Fume 28

Fig.4.6.NaOH 28

Fig.4.7. Na2SiO3 29

Fig.4.8. Distilled Water 29

Fig.4.9. Sulfur 30

Fig.4.10. Oil 30

Fig.4.11. Caliper 31

Fig.4.12. Digital Scale 31

Fig.4.13. Measuring Cup 32

Fig.4.14. Gardener Standard Colors 32

Fig.4.15. Erlenmeyer Flask 33

Fig.4.16. Sieve and Sieve Machine 33

Fig.4.17. Beaker Glass 34

Fig.4.18. Sticky Plastic 34

Fig.4.19. Abrams Cone 35

Fig.4.20. Mortar 35

Fig.4.21. Cylinder Mold 36

Fig.4.22. Oven 36

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Fig.4.24. Brush 37

Fig.4.25. Capping 38

Fig.4.26. Plastic Bucket 38

Fig.4.27. Pan 39

Fig.4.28. Plate 39

Fig.4.29. Ruler 40

Fig.4.30. Wagon 40

Fig.4.31. Shovel 41

Fig.4.32. Hammer 41

Fig.4.33. Iron to Pound the Mixture 42

Fig.4.34. Plastic Bag 42

Fig.4.35. Stationer 43

Fig.5.1.Weight Density in 14 Days Chart 63 Fig.5.2. Weight Density in 14 Days Chart 64 Fig.5.3. Compressive Strength Column Chart 66 Fig.5.4. Compressive Strength Line Chart 66 Fig.5.6. Modulus of Elasticity Chart 69

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LIST OF EQUATION

2-1. Poly-condensation Process 9

3-1. Area of Cylinder 19

3-2. Magnitude of the Compressive Strength 20 4-1. The Amount of Mud of Sand 45 4-2. Water Content of Fine Aggregate 47 4-3. The Amount of Mud of Coarse Aggregate 48 4-5. Water Content of Coarse Aggregate 50 5-1. Calculation of the Amount of Mud in Sand 57 5-2. Calculation of the Amount of Mud in Coarse Aggregate 59

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ABSTRACT

COMPRESSIVE STRENGTH AND MODULUS OF ELASTICITY OF GEOPOLYMER CONCRETE WITH METAKAOLIN AND SILICA FUME,

Garudea Martha Handyaningtyas, Student Number 111313777, year of 2015, Structural engineering, Civil Engineering International Program, Faculty of Engineering, UniversitasAtma Jaya Yogyakarta.

Geopolymer concrete is concrete which uses different materials and are environmental friendly during the production process. There are several advantages of geopolymer concrete; such as anti-fire, used as a cover material for the exterior of mechanical equipment, durable and environment friendly. Geopolymer also produced by the chemical reaction of alumina-silicate oxides (Si2O5, Al2O2) with alkali Poly-silicate yielding polymeric Si–O–Al bonds.

Geopolymer concrete is concrete without cement as a bond but, geopolymer concrete uses alkali activator as a bond of the concrete.

This research studies about compressive strength and modulus of elasticity of geopolymer concrete with metakaolin and silica fume as solid materials. The proportions of solid material are 25%, 50% and 75% for the metakaolin, while the proportion of silica fume is 5%. The alkali activators in this research are NaOH and Na2SiO3. The proportions of NaOH and Na2SiO3is are 2:1. The aggregates in this research are coarse aggregate (split) and fine aggregate (sand) with the proportion of 2:1. The samples in this research are 18 samples. 9 samples cylinder with the size are 70mm x 140mm and the other 9 samples cylinder with the size are 150mm x 300mm. Compressive strength test is done at the age of 14 days and 28 days. The compressive strength test is using Universal Testing Machine (UTM).

Based on the compression strength test that has been done, the value of the average compressive strength at 28 days with comparative precursor (metakaolin:silica fume) 25:5, 50:5, 75:5 are 1.149 MPa, 0.641 MPa and 0.178 MPa, respectively. Based on modulus of elasticity test that has been done, the value of the average modulus of elasticity at 28 days with comparative precursor (metakaolin:silica fume) 25:5, 50:5, 75:5 are 2.866 MPa, 2.371 MPa and 1.143 MPa, respectively.

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CHAPTER I

INTRODUCTION

1.1.General Background

Every people need to build a house for make them safe from any other external conditions and things that it can be happen in the world. So, the house should be strong, safe and comfortable for people. Not only house, people need another great building for work, control the health of human, hang out, and so on. If the building is strong people feels safe and if people feels safe it means that people will feel comfortable to live or doing something in that building.

Build a building is not simple, people should prepare the materials and construct step by step. Before preparing the right materials, people should know the mechanics properties of material whether it is strong or not for the building, environmental friendly or not, has a bad effect for the structure of the building or not and so on.

There are several materials that should be prepared before constructing the building such as steel, concrete, iron, rock, water, sand, gravel and so many other materials. Every single material should have a good quality and should be strong enough for the building.

Concrete is one of the important materials for buildings. Concrete should be strong enough and have a good quality. To make good quality of concrete, people

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should find right materials that will be used. “So far we know concrete is the most popular building material, composed of the main composition of the rock (aggregate), water, and portland cement (commonly called cement only.” (Hardjito, 2002)

Now, people meet some problems in utility of Portland cement for concrete. The first attention about cement is gas emissions; GHG (carbon dioxide) produced in the cement production process. To produce 1 ton of cement, the emissions that produced also 1 ton. The emissions released to the atmosphere will make global warming. This condition makes Davidovits (1970) from France was started to do a research about material that used for pyramid because a lot of building include pyramid in Egyptian can last a long time and there is no global warming or emission problem because of the materials.

People thought that Pyramid is like Borobudur Temple that construct by bricks. But, Davidovits (1979) proves that Pyramid is different with Borobudur Temple. From the research of Davidovits (1970) raise the result that chemical structure and the material structure that used for build a Pyramid was same with the material of the geopolymer concrete.

In geopolymer concrete people replace cement with fly ash. So, the material will be environmental friendly. Geopolymer concrete is said environmental friendly because fly ash comes from the combustion of stone embers that have no toxic solvents. During this time, fly ash (the small size of particles and therefore easy to fly in the air) not more properly used or only used as a heap.

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Irresponsibility dumping potentially threatens environmental sustainability, fly ash can easy to fly and make air pollution. Particles of heavy metals that contain in fly ash can also easily soluble and contaminate the water sources. To dissolve the elements silicon and aluminum in the fly ash people will use alkali activators. Alkali activators containing sodium hydroxide and sodium silicate or a potassium hydroxide and potassium silicate will be calcium in the geopolymer concrete. This material from fly ash and alkali activators will mixed with aggregate and be a geopolymer concrete. So, this concrete would not using cement again. This fly ash and the calcium will be mixed together become a stronger chain. In this paper the writer tries to replace fly ash by metakaolin and silica fume to test the compressive strength and modulus of elasticity of the geopolymer base on those two materials.

Metakaolin is a dehydroxylated form of the kaolin. Kaolin is a clay mineral, with the chemical composition Al2Si2O5(OH)4. “Metakaolin was taken from

Gunung Kidul County, province of Yogyakarta. In this research metakaolin was also burnt at 500 Celcius during 25 minutes. Metakaolin burnt at 500 celcius contain of SiO2 + Al2O3 + Fe2O3.”(Lisantono and Hatmoko, 2012)

Silica fume is the material which has same composition with metakaolin. Both of them consist of silica and calcium with the different proportion. The reason of using 2 materials (metakaolin and silica fume) is because the silica fume is just an addition to make the concrete stronger after the NAOH decrease the strength

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of the metakaolin. The silica fume is an addition because between metakaolin and silica fume the highest value of Si is silica fume, it is better to make the silica fume as the addition.

1.2.Problem Statement

Based on the background above the problem statement is:

 “What is the effect of the metakaolin and silica fume to the compressive strength of the geopolymer concrete?”

 “How many percent of metakaolin that will be used to make a strong

geopolymer concrete?”

1.3.Problem Limitation

In order to focus on a specific problem, there must be some limitation in this final project, such as:

1. Geopolymer concrete with metakaolin and silica fume as the main materials

2. The size of the specimens will be 70mm x 140mm and 150mm x 300mm.

3. The tests that will be done are compressive strength and modulus elasticity.

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4. The percentages of metakaolin in the specimen that will be tested are 25%, 50% and 75% from the weight of concrete.

5. The addition of silica fume will be 5% of the weight of concrete. 6. Concentration of NaOH will be 12 M

7. Percentage of NaOH : Na2SiO3 is 2:1

8. Ratio of Alkali Activator to the aggregate is 1:3

9. Curing method of the geopolymer concrete is dry curing. The concrete will be put into the oven as long as 24 hours with the heat of the oven is 80°C.

10.The process of making geopolymer concrete. 11.The analysis based on the research.

1.4.Objectives

The objectives of this final project are:  To examine the geopolymer concrete

 To give an information about the differences between ordinary concrete and geopolymer concrete.

 To explain to the reader about the advantage of geopolymer concrete.  To give an information about “how to make geopolymer concrete”

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1.5.Final Project Originality

There are some topics about geopolymer concrete with fly ash and superplasticizer in the library of Universitas Atmajaya Yogyakarta. But, the topic about “Geopolymer Concrete with Metakaolin and Silica Fume” has never been used on any other final project before.

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CHAPTER II

LITERATURE REVIEW

There are some theories and research that will be used as references and comparison for this project

2.1.Theories

According to Davidovits (2011), Geopolymer can be defined as material resulting from biosynthesis polymeric aluminosilicate and alkali-silicate that produce a polymer framework SiO4 and AlO4 tetrahedra bound.

The main advantage of Geopolymer concrete is that it is environmental friendly. To produce a good quality of geopolymer concrete, it needs to be mixed with alkali activator

According to Jiang (1997), “alkali activation is the term used to imply that

alkalis or alkali earth ions are used to stimulate the pozzolanic reaction or release the latent cementitious properties of finely divided inorganic materials. The materials could be minerals as well as industrial by-products consisting

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According to Bakharev, Sanjayan, & Cheng, (1999), recent research has shown that it is possible to use 100% fly ash or slag as the binder in mortar by activating them with an alkali component, such as; caustic alkalis, silicate salts, and non-silicate salts of weak acids.

According to Brough & Atkinson, (2002); Deja, (2002), there are two models of alkali activation. Activation by low to mild alkali of a material containing primarily silicate and calcium will produce calcium silicate hydrate gel (C-S-H), similar to that formed in Portland cements, but with a lower Ca/Si ratio.

2.2.Another Research to Compare

2.2.1. Thesis Research

According to Efendi (2014), discus about the effect of solid material; fly ash and rice husk ash to geopolymer concrete with alkaline activator sodium silicate and sodium hydro. The materials that were used are fly ash, rice husk ash, fine aggregate, coarse aggregates, and distilled water. The compression test value of the research in 28 days: 100:0, 95:5, 90:10, 85:15, 80:20, 75:25 are 17.43834 MPa, 3.571159 MPa, 6.940354 MPa, 7.093094 MPa, 3.051927 MPa, 2.960489 MPa. Geopolymer concrete with fly ash 100% can be used as structural concrete if the working process is done correctly. In this research the highest value of compression strength is 21.20305.

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According to Sitindaon (2014), his final project discussed about the effect of plasticizer to the compressive strength of geopolymer concrete. This concrete also uses fly ash and rice husk ash with alkaline activator sodium silicate and sodium hydro. The differences between these two topics are plasticizer. The materials of this concrete are fly ash, rice husk ash, aquades, fine aggregate, coarse aggregate, activator; Sodium Silicate (Na2SiO3) and

Sodium Hydroxide (NaOH). In geopolymer, there is a reaction between alumina-silicate oxide (Si2O5, Al2O2) and alkali poly-silicate that have

Si-O-Al as the reaction.

(2-1) Based on the research the compression strength values with plasticizer as follows:

100:0 = 9.71 MPa, 95:5 = 1.69 MPa, 90:10 = 4.38 MPa, 85:15 = 73 MPa, 80:20 =1.21 MPa, 75:25 = 3.37 MPa while the compression strength values without plasticizer in 28 days as follows:

100:0 = 17.44 MPa, 95:5 = 3.57 MPa, 90:10 = 6.94 MPa, 85:15 = 7.09 MPa, 80:20 = 3.05 MPa, 75:25 = 2.96 MPa

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According to the research of Lisantono and Hatmoko (2009), in their research about Geopolymer Concrete Made with Bagasse Ash and Metakaolin, the compressive strength values of the three types of Geopolymer Concrete are generally very low. At 14 days, the compressive strength values as follows: bagasse ash = 0.325 MPa, metkaolin = 0.560 MPa, bagasse ash and metakaolin = 0.380 MPa while the compressive strength values at 28 days as follows: bagasse ash = 0.344 MPa, metkaolin = 0.721 MPa, bagasse ash and metakaolin = 0.852 MPa. However, geopolymer concrete based on the mixture of bagasse-ash with metakaolin gives the highest compressive strength compared to other and can be developed for future research.

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CHAPTER III

BASIC THEORY

3.1.Geopolymer Concrete

Geopolymer concrete is concrete which uses different materials and are environmental friendly during the production process. There are several advantages of the materials; such as anti-fire, used as a cover material for the exterior of mechanical equipment, durable and environment friendly.

Geopolymer concrete was established by Joseph Davidovits in 1970. At that time, Davidovits investigated the materials which were in the pyramid. He found that the cement used in the pyramid consist of several different materials. At that time it was called geopolymer, which was obtained from fly ash as a result of geo-polymerization reaction mix with NaOH, KOH and so on. In the process of geopolymer, there is a chemical reaction between alumina-silicate oxide (Si2O5, Al2O2) with alkali poly-silicates which produces Si-O-Al bonds. Poly-silicate is generally in the form of sodium or potassium silicate obtained from the chemical industry or fine silica powder as a byproduct of the process ferro-silicon metallurgy. From the reactions that mix together in the geopolymer, there will be H2O or water that has been released.

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From the equation, it can be shown that the chemical reaction of compound formation geopolymer also produces water that will be removed during the curing process. (Davidovits, 1999; Hardjito & Rangan, 2005)

Actually, geopolymer concrete can be produced no only from fly ash but geopolymer can be also produced with silica and materials rich in alumina. Several studies have reported the use of geopolymer in concrete is beneficial. Most of the studies investigated the use of alkali activators containing sodium hydroxide and sodium silicate; or potassium hydroxide and potassium silicate.

Different with the material that is used above, Cheng and Chiu (2003) reported the production of geopolymer concrete using slag and metakaolin with potassium hydroxide and sodium silicate as the alkaline medium. Some of people using fly ash as a material in geopolymers with sodium hydroxide and sodium silicate as well as with potassium hydroxide with potassium silicate combinations. The results from the studies show that the formation of geopolymer is excellent. It can be noted that the presence of calcium content in fly ash, played a significant role in compressive strength development. The addition of calcium ions, provide a faster reaction and thus produces good hardening of geopolymer in shorter curing time.

“Polymers are sensitive towards heat and can form a stronger chain due to polycondensation. It is noted from the basic chemical reaction when subjected to heat causes silicon and aluminium hydroxide molecules to polycondense or

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polymerizes, to form rigid chains or nets of oxygen bonded tetrahedra.”

(Hindawi, 2013)

Davidovits (1988) reported that geopolymer can harden rapidly at room

temperature and can gain the compressive strength up to 20 MPa. Geopolymer

cement was discovered to be acid resistant, because, unlike the Portland cement, geopolymer cements does not depend on lime and are not dissolved by acidic solutions.

3.2.Metakaolin

Metakaolin is a dehydroxylated form of the kaolin. Kaolin is a clay material with low iron content, and generally white in color. Kaolin has a composition of hydrous aluminum silicate (2H2O.Al2O3.2SiO2), along with other minerals.

Kaolin will be transformed under when affected by heat at atmospheric pressure. If kaolin is burn at temperatures of 550-800C, kaolin will be dehydroxylated and produce disorder metakaolin (Al2Si2O7). However, if the

kaolin is burnt at temperature of 900C, it will cause the loss of hydroxyl continuously and gradually oksolasi on metakaolin. This makes metakaolin has a complex mixture of amorphous silica (SiO2) and alumina (Al2O3).

If the kaolin is burnt up to 925-950C, it will change from metakaolin to be aliminium-silicon spinel (Al3Si4O12), which is also known as a gamma-alumina

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If the kaolin is burnt up to 1050C, it will cause spinel phase (Si3Al4O12)

nucleate and transformed into mullite (3Al2O3. 2SiO2), and crystalline

cristobalite (SiO2).

So, the best combustion of kaolin is in the heat of 550-800C

3.2.1. Advantages of Metakaolin

The advantages of metakaolin are:

 Increase compressive and flexural strengths

 Reduce permeability (including chloride permeability)

 Reduce potential for efflorescence, which occurs when calcium is transported by water to the surface where it combines with carbon dioxide from the atmosphere to make calcium carbonate, which precipitates on the surface as a white residue.

 Increase resistance to chemical attack  Increase durability

 Reduce effects of alkali-silica reactivity (ASR)

 Reduce shrinkage, due to "particle packing" making concrete denser  Improve color by lightening the color of concrete making it possible

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3.2.2. Use of Metakaoline

 High performance, high strength, and lightweight concrete  Precast and poured-mold concrete

 Fibercement and ferrocement products  Glass fiber reinforced concrete

 Countertops, art sculptures  Mortar and stucco

3.3.Silica Fume

Silica Fume Is a high performance pozzolan with unique chemical and physical properties that enable cement based systems and mix designs to achieve higher levels of performance and durability.

Silica fume is a byproduct of silicon metal and ferrosilicon alloy product. “ By-products of the production of silicon metal and the ferrosilicon alloys having silicon contents of 75% or more contain 85–95% non-crystalline silica. The by-product of the by-production of ferrosilicon alloy having 50% silicon has much lower silica content and is less pozzolanic.Silica fume usually contains of 90% SiO2.” (Vishnumaya 2014)

Silica Fume will greatly increase concrete strength and reduce permeability which in turn contributes to increased durability for chemical resistance, chloride attack, sulfate attack, and abrasion resistance.

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Silica fume is an ultrafine material with spherical particles less than 1 μm in diameter, the average being about 0.15 μm. This makes it approximately 100

times smaller than the average cement particle

Silica fume is like an addition in the cement to improve its properties; compressive strength of the cement, abrasion resistance, and bond strength. The silica fume that is added to the cement can reduce the permeability of the concrete to chloride ions. It can protect the reinforcing steel of concrete from corrosion, especially in the chloride-rich environments.

Because of the addition of silica fume to the cement, the slump loss with time is directly proportional to the increase in the silica fume content, due to the introduction of large surface area in the concrete mix by its addition. Although the slump decreases, the mix remains highly cohesive.

Silica fume reduces bleeding significantly, because the additional water is consumed in wetting of the large surface area of the silica fume and hence the free water left in the mix for bleeding also decreases. Silica fume also blocks the pores in the fresh concrete so water within the concrete will not flow out.

3.4.Alkali Activator

The combination of liquid sodium silicate and sodium hydroxide are used to aid the chemical reaction with aluminum and silica contained in metakaolin and silica fume.

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Sodium hydroxide is an alkaline compound that is highly reactive when mixed with water or distilled water. Sodium Hydroxide is solid and is used to reacts Si and Al, which in turn produce a strong bond polymerization. Sodium Silicate is like a gel and serves to accelerate the polymerization reaction. When dissolved in water or distilled water, sodium silicate will form an alkaline solution.

3.5.Aggregate

The number of aggregate in the concrete mixture is usually 60% - 70% of the weight of the concrete. It is because the size of aggregate is huge. So, it can fill the cylinder properly.

The use of Aggregate

 Reduces the use of pozzolan or alkali activator.  Produce a strong concrete.

 Reduces shrinkage in the concrete hardening.  Achieving solid concrete composition.  Control the workability of the concrete.

Based on the size classification, aggregates are divided into two types; coarse aggregate and fine aggregate. Coarse aggregates are rock aggregates with the size of aggregates larger than 4.75 mm. Fine aggregates are smaller than 4.75 mm called sand. Aggregates with the size smaller than 1.2 mm are called fine sand. Aggregates that are smaller than 0.075 mm are called silt. Aggregates that

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are smaller than 0.002 mm are called clay. In general, aggregates are classified into 3 types:

 Stone, size larger 40 mm.

 Gravel, with size ranges from 5 to 40 mm.  Sand, the size ranges between 0.15 to 5 mm

Coarse aggregate also divided into 3 types based on weight:

 Heavy aggregate

Specific gravity of heavy aggregate is more than 2.8 g/cm3. Example of heavy aggregate is magnetil (Fe3O4), barites (BaSO4) or iron filings. The resulting concrete has a high density that is up to 5 g / cm3 is used as a protective wall.

 Normal Aggregate

Specific gravity of normal aggregate is between 2.5 - 2.7 g/cm3. This aggregate is usually derived from granite, basalt, quartz and so forth. The resulting concrete has a weight of 2.3 g/cm3.

 Lightweight aggregate

Lightweight aggregate is aggregate with the specific gravity less than 2 g/cm3, for example ground fuels (Bloated clay), fly ash, and blast furnace slag foam. This aggregate is usually used for lightweight concrete which is usually used for non-structural elements.

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Viewed from the surface texture, the surface condition of the aggregate will affect the ease of work. The more slippery surface concrete aggregate will be the more easily done. However, the type of aggregate with a rough surface is preferred because it will produce a strong bond between aggregate and cement paste. (Mulyono, 2004).

3.6.Distilled Water (Aquades)

Distilled water is water distillation. Distilled water is used to dissolve the Natrium Oxide and as the addition water of the mixture.

3.7.Compressive Strength

Compressive strength of concrete is the ability of concrete to receive a compressive force per unit area. Compressive strength of the concrete identifies the quality of a structure. The higher power of the structure so the higher quality of concrete that will be resulting (Mulyono, 2004). The area of concrete is cylinder. It can be seen from the figure 3.1; the height (h) and the diameter (d) are the factors which will be used to measure the area of the cylinder. The formula for area is:

(3-1)

with :

20

r = Radius (cm2)

The load (p) is needed to test the compressive strength of the concrete. The load will be used to compress the concrete until the concrete is crack. The cylinder can be seen in figure 3.1

Figure 3.1. Cylinder Sample

The formula that will be used to find the magnitude of the compressive strength of concrete is:

21

with :

P = Maximum load (kg).

A = Cross-sectional area of the specimen (cm2).

fc ' = Characteristic concrete compressive strength (kg/cm2).

3.8.Modulus of Elasticity

The modulus of elasticity is often referred to as the Young's modulus which is a comparison between stress and axial strain in the elastic deformation. So modulus of elasticity showed a tendency of a material to deform and back again to its original shape when under load (SNI 2826-2008).

3.9.Slump Value

Slump value is used to measure the ropy level of concrete mixture which has an effect with the workability of the concrete mixture process. If the value of the slump test is large then the concrete is liquid and easier to work with, otherwise if the value of the slump is small, the concrete will be more viscous and more difficult to work with.

3.10. Workability

Workability of concrete workmanship is the ease condition in mixing, stirring, pouring into molds and being compact without reduce the homogeneity of the

22

concrete and bleeding concrete (separation) excessively to achieve the higher concrete strength.

Characteristics of Workability

 Consistency

Workability is depends on the composition of the fresh concrete, physical characteristic from the mixture and aggregate.

 Mobility

Ease to mix the mixture, put the mixture into the mold, and compaction.

 Compact ability

Ease to compact the mixture so that the air cavities can be reduced.  Stability

The ability of the concrete to always homogeneous, always binding (coherent), and there will be no grain separation (segregation and bleeding).

 Finish ability

Ease of the concrete to reach the final stage which is hardened with good conditions.

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3.11. The Age of Concrete

The age of concrete is important to be considered in the experiment because the strength of the concrete will rise for every day. At the first time the strength of the concrete will be increase very fast and after that it will be relatively small in the age of 28days. The age of concrete is calculated from the time when the concrete is removed from the mold.

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CHAPTER IV

RESEARCH METHODOLOGY

4.1.Research Metodology

Research methodology is the process to collect information and data about the topic through surveys, questionnaires, interviews, practice to the laboratory (research) and so on to get the result that needed.

The type of this method is research. The objective of this research is to know the compressive strength and modulus of elasticity of geopolymer concrete with metakaolin and silica fume. The first step is make the activator. The way to make the activator is mixed NaOH 0.03 with 1000ml of water and wait for 24 hours. After that, the NaOH 12 M will be mixed with Na2SiO3. Pasta geopolymer is

done. Metakaolin, silica fume and aggregate are mixed together in a big place. After all, the pasta geopolymer will be pour into the big place that already filled by the aggregate, metakaolin and silica fume. After mix all of the materials and alkali activator, the geopolymer pasta will be ready to put into the mold.

There are two tests that will be used to test the geopolymer concrete. First, test the compressive strength of the specimen. There will be 9 samples to test the compressive strength in 14 days in small cylinder. Second, test the modulus elasticity and the compressive strength of the 9 big cylinders. The size of the

25

small cylinder will be 70 x 140 mm and the size of the big cylinder will be 150 x 300 mm.

4.2.Specification of Specimen

There are 2 types of test; 1) Compressive strength and 2) modulus of elasticity. The material variable that will be change is metakaolin; 25% of the total weight of concrete, 50% of the total weight of concrete and 75% of the total weight of concrete while the variable of silica fume will be constant; 5%. In the previous research from Lisantono and Hatmoko (2012) the proportion of the metakaolin is 50% and the result of the concrete with metakaolin is highest compared with the baggase ash and baggase ash + metakaolin. But, the value still lower than the value of Portland cement. In this research, the writer uses 25% and 75% for the proportion because the writer wants to check that the highest value of compressive strength based on metakaolin is in fewer than 50% or more than 50%. The writer also check the value in 50% to know whether the value of geopolymer in 50% with silica fume is higher or not compare with the geopolymer concrete based on metakaolin only.

4.3.Research Framework

The purpose of the research framework is to list the research to be more systematic and efficient. The flow chart of the research can be seen in Figure 4.1.

26

Figure 4.1 Flowchart of Research Framework

4.4.Materials

There are some materials to make the samples such as fine aggregate, coarse aggregate, aquades, metakaolin, silica fume, NaOH and Na2SiO3. There is the specification of each material:

1. Fine aggregate such as sand from Kali Progo, Sleman, Yogyakarta. The fine aggregate can be seen in Figure 4.2.

Figure 4.2 Fine Aggregate

Start Prepare the

Materials

Check the materials

Design the mixture of the speciment

Make the speciments

Concrete treatment

Compressive Strength and Modulus Elasticity

27

2. Coarse aggregate such as kerikil dengan ukuran maksimum agregar 10 mm yang berasal dari Kali Clereng, Kulon Progo, Yogyakarta. The picture of coarse aggregate can be seen in Figure 4.3.

Figure 4.3 Coarse Aggregate

3. Metakaolin that was taken from Gunung Kidul. The picture of metakaolin can be seen in Figure 4.4

28

4. Silica Fume that was taken from CV. Geonika Beton Utama jl. Tinosidin (sutopadan) 95A Ngestiharjo, Yogyakarta. The picture of Silica Fume can be seen in Figure 4.5

Figure 4.5 Silica Fume

5. The type of NaOH was Sodium Hydroxide Pellets for analysis EMSURER ISO. Hydroxide Pallets for Analysis can be seen in Figure 4.6.

29

6. The type of Na2SiO3 was Sodium Silicate Solution Extra Pure. Na2SiO3 can be seen in Figure 4.7

Figure 4.7 Na2SiO3

7. Distilled water. The picture of distilled water can be seen in Figure 4.8.

30

8. Additional materials are sulfur and oil. The sulfur is used for capping the surface of the concrete and the oil is used for cover the plastic, so it will help to release the cylinder from the mold easily. The pictures of sulfur and oil can be seen in Figure 4.9 and 4.10.

Figure 4.9 Sulfur

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4.5.Tools

Beside the materials, tools are also important things of research because without tools, there will be no process to make the specimen. In this compressive strength and modulus elasticity research, the estimate tools that needed are:

1) Caliper is used to measure the dimensions of the aggregate. The aim to measure the aggregate is to equate all of the size of aggregates. The calipers can be seen in Figure 4.11.

Figure 4.11 Caliper

2) Digital scales, which are used to weigh the material. The pictures of the digital scales can be seen in Figure 4.12.

32

3) 250 ml measuring cup, which is used to test the content of silt and organic content in the fine aggregate. 150 ml measuring cup is used to take the distilled water and put into the beaker glass to make the NaOH 12M. The measuring cup can be seen in Figure 4.13.

Figure 4.13 Measuring Cup

4) Gardner Standard Colors is used to measure how much of the organic matter content in the fine aggregate. The Gardener Standard Color can be seen in Figure 4.14.

33

5) Erlenmeyer flask capacity of 500ml was used to test the specific gravity and absorption of fine aggregate. The Erlenmeyer Flask can be seen in Figure 4.15.

Figure 4.15 Erlenmeyer Flask

6) Sieve with size 100mm and sieve machine are used to grading tests metakaolin. The sieve can be seen in Figure 4.16.

34

7) Beaker glass 1000ml is used as a place to make NaOH 12M. The beaker glass can be seen in Figure 4.17.

Figure 4.17 Beaker Glass

8) Sticky plastic which is used to cover the inside mold from the mixture. So, the mixture will be not sticky to the mold. The sticky plastic can be seen in Figure 4.18.

35

9) Abrams cone is used to identify and determine the value of the slump before the sample put into the cylinder. Abrams cone is truncated cone with a diameter of over 100 mm, bottom diameter of 200 mm and has a height of 300 mm. The abrams cone can be seen in Figure 4.19.

Figure 4.19 Abrams Cone

10) Concrete Mortar tub is used as a base to make the mixture. The Concrete Mortar tub can be seen in Figure 4.20.

36

11) Cylinder molds with the diameter are 70 mm and 150 mm and the height are 140 mm and 300 mm. The cylinder molds can be seen in Figure 4.21.

Figure 4.21 Cylinder mold

12) Oven is used to curing geopolymer concrete. The oven can be seen in Figure 4.22.

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13) Universal Testing Machine (UTM) with the brand Shimadzu UMH-30 is used to test the compressive strength of geopolymer concrete. The UTM with the brand is Shimadzu can be seen in Figure 4.23.

Figure 4.23 Universal Testing Machine (UTM)

14) The Brush will be used to smear the oil onto the sticky plastic. The brush can be seen in Figure 4.24.

38

15) The capping is used as a place of sulfur. After the sulfur is placed on it, the concrete will be put onto the capping. If the sulfur is already dry, take the concrete off. The capping can be seen in Figure 4.25.

Figure 4.25 Capping

16) The plastic bucket is used as a place of aggregate and sand. The plastic bucket also used as a place of the geopolymer mixture. The plastic bucket can be seen in Figure 4.26.

39

17) The pan is used as a place to cook the sulfur. The pan can be seen in Figure 4.27.

Figure 4.27 Pan

18) The plate is used as a place of oil, sand, coarse aggregate and so on. The plate can be seen in Figure 4.28.

Figure 4.28 Plate

40

19) The ruler is used to measure the size of cylinder and measure the sticky plastic. The ruler can be seen in Figure 4.29.

Figure 4.29 Ruler

20) The wagon is used to carry the mold from one place to the other place. The wagon can be seen in Figure 4.30.

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21) The shovel is used to stir the mixture and take the materials. The shovel can be seen in Figure 4.31.

Figure 4.31 Shovel

22) Hammer is used to hit the mold. When the mixture is put into the mold, the outside wall of the mold should be tapped with hammer. The aim of tap the mold is to make the mixture in the mold fill the blank spaces. The hemmer can be seen in Figure 4.32.

42

23) The iron is used to pound the mixture in the mold. The aim of the iron is same with the hammer but directly into the mixture. The iron can be seen in Figure 4.33.

Figure 4.33 Iron to Pound the mixture

24) The plastic bag is used as a place of some materials. Sand, metakaolin coarse aggregate and silica fume can be put into the plastic bag to keep the materials from the outside condition. The plastic bag can be seen in Figure 4.34.

43

25) The stationery is used to help the writer to complete the works such as cut the paper, sticky plastic, write, make a line, and erase. The stationery can be seen in Figure 4.35.

44

4.6.Material Testing

Before start to make the specimen there should be a test to each material. The aim of test the material is to determine the feasibility of the material to be used. In this experiment there will be 3 material tests that will be done; fine aggregate, coarse aggregate, and metakaolin. The aim of metakaolin test is to know the chemical content inside the metakaolin. Whereas to test the feasibility of fine aggregate and coarse aggregate is carried out as follow

4.6.1. Fine Aggregate

1. Determine the organic substance in the sand

 Put the dry sand into measured glass 250cc until reach the 130 cc.  Pour NaOH 3% to that measured glass until it reaches 200cc.  Shake the sand and NaOH 3% in ± 10 minute and let it in 24

hours.

 Write the color of the liquid that happened on the top of the sand

and compare it by using “Gardner Standard Color”. 2. Determine the amount of mud in sand

 Take 100gr oven-dried sand and pour into the measured glass 250 cc.

45

The Amount of Mud = �_� x100%

 Pour the water into measured glass until 12cm above the sand, marked by rubber. After that, shake it in 1 minute and let it in 1 minute so the sand will sink.

 Dirty water above the sand is pour out, the sand stays in the measured glass.

 Then pour water into measured glass, same as in process 1 – 3. Do it continuously until the water is clear.

 After the water is clear, pour the water out and pour the sand into the plate.

 Dry the sand in the oven at 105°C – 110°C about 24 hours.  Take the sand from the oven and put in the cool desiccator.  After cooling the sand, measure the weight (B gram).

 Calculate the amount of mud in the sand:

(4-1)

with:

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3. Density and Absorption

 Weigh ± 500 grams of sand from sieve 4 and soak in water for ± 24 hours.

 Dry the aggregate so the aggregate can reach the SSD (Saturated Surface Dry).

 Put the fine aggregate into the cone to determine whether the aggregate reach SSD or not.

 First put 1/3 and then pound it for 8 times. Then put again to 2/3 and pound it for 8 times. Then put until full and pounded 8 times, and the cone is filled to the top.

 Lift the cone slowly. If there is a decrease of at least 1/4 and 1/3 of the maximum height of the cone, then the aggregate in an SSD  Put the aggregate into the Erlenmeyer flask of 500 grams, and then

add the water up to the limit of 500 ml.

 Stir the mixture in Erlenmeyer flask to remove the air bubbles in it. After that, put the Erlenmeyer flask is in a bucket of water (water covered the flask to the limit of water in the Erlenmeyer flask) wait for ± 1 hour. Add water up to 500 ml and weighed. Then, the sand and the water is released into a cup, let it settle. After settles throw away the water.

47

 Put the sand into the oven at 110 ° C for ± 24 hours, chill it, and weighed.

4. Water Content

 Prepare the pan in the dry condition and weighed it.

 Put 100 grams of fine aggregate into the pan and then weighed.  Put the pan which already filled with the fine aggregate into the

oven with the temperature is 110°C for 24 hours.

 After 24 hours, chill the pan which already filled with fine aggregate, then weighed. Note the results.

 The water content of the aggregates is calculated by the formula: (4-2)

with:

A = The weight before aggregate before put into the oven

B = The weight before aggregate before put into the oven

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The Amount of Mud = �

� x100%

4.6.2. Coarse Aggregate

1. Determine the amount of mud in sand

 Take 100gr oven-dried coarse aggregate (split) and put it into the pan.

 Fill the pan with water until the split is submerged, stir for 1 minute and let stand for 1 minute.

 Dirty water above the split is poured out but the split stays in the measured glass.

 Then pour water into the measured glass, same as in process 1 – 3. Do it continuously until the water is clear.

 After the water is clear, pour the water out and pour the split into the plate.

 Dry the c split in the oven at 105°C – 110°C about 24 hours.  Take the split from the oven and put in the cool desiccator.  After cooling the sand, measure the weight (B gram).

 Calculate the amount of mud in the Coarse Aggregate:

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2. Density and Absorption

 Splits retained on ½” are taken then weighed as much as 1000 gr.  The splits are soaked for 24 hours and washed thoroughly.

 These splits in the water bucket are weighed but first the bucket should be weighed with the water.

 The splits are dried using a cloth until reach the SSD (Saturated Surface Dry), and then the split are weighed.

 The splits are dried in the oven at 110° C until dry.

 Aggregate cooled in the desiccator with a temperature of 25°C, and then weighed.

 Then the calculated density and absorption of aggregates as in appendix A.4.

3. Water Content

 Prepare the pan in the dry condition and weighed it.  Put 1000 grams of splits into the pan and then weighed.

 Put the pan which already filled with the splits into the oven with the temperature is 110°C for 24 hours.

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 After 24 hours, chill the pan which already filled with splits, then weighed. Note the results.

 The water content of the aggregates is calculated by the formula: (4-5)

with:

A = The weight before aggregate before put into the oven

B = The weight before aggregate before put into the oven

4.7.Specimen Testing

Make the calculation and planning should be considered before make the specimen. The calculation and planning are called geopolymer concrete mix design. Because there is no definitive determination of its manufacture, geopolymer concrete mix design was made by the method of weight ratio.

The percentage of aggregate, activator, metakaolin, and silica fume in this research was referred to the mix design of the thesis which was done by Efendi (2014) with the title of the thesis is “Pengaruh Komposisi Solid Material Abu Terbang dan Abu Sekam Padi pada Beton Geopolimer dengan Alkaline Activator

Sodium Silikat dan Sodium Hidroksida” and from the research of Lisantono and

51

Hatmoko (2009) with the title of the research is “The Compressive Strength of Geopolymer Concrete Made with Bagasse Ash and Metakaolin”

The amount of specimen that will be done is 18 specimens with the kind of variant such as shown in table 4.1

Table 4.1 The Amount of Specimens

Age of the Experiment

Metakaolin : Silica Fume Amount of the Specimens 25:5 50:5 75:5

14 Days 3 3 3 9

28 Days 3 3 3 9

The difference between geopolymer concrete and conventional concrete is in the cement. Conventional concrete use cement while the geopolymer concrete replaces the cement with geopolymer pasta to bind the entire component.

Step to make geopolymer concrete: 1. Prepare of Pozzolan

The pozzolan in this experiment is metakaolin and silica fume. The metakaolin is a material comes from the combustion of kaolin. Metakaolin will be burn in 800°C and after that it will be sieved in sieves 100mm. Both metakaolin and silica fume are prepared according to the proportion that already planned.

52

2. Step to Make an Activator

a. The molarity of NaOH that will be used is 40g/mol. To make a concentrated solution of NaOH 12M, the composition will be 12x40 = 480 grams of NaOH. After that NaOH will be diluted with 1 liter of distilled water. Stir the NaOH mixed with the distilled water and wait until the solution is cold. b. The solution of NaOH that already made will be mixed with

Na2SiO3 with the ratio of 2:1 and stir until completely mixed. Let stand the activator solution for 24 hours at room temperature

3. Prepare the rigid plastic and cover it with oil. Put the plastic on the wall of inside mold.

4. After 24 hours the Alkali activator will be mixed with Pozzolan and the aggregate. The ratio of aggregate and alkali activator will be 3:1. The composition of the metakaolin will be 25%, 50% and 75% of the concrete weight and the composition of the silica fume will be 5% of the concrete weight.

5. After all of the mixture is mixed properly, do slump test for the geopolymer concrete mix.

6. After that, geopolymer concrete was put into the molds and after reach 1/3 of the height of mold pound 25 times. Pour the geopolymer to the mold again, after reach 2/3 of the height of mold pound it again

53

for 25 times. Pour the geopolymer until full and then flatten the surface of it.

7. Put the concrete mix with the mold into the the oven at 80°C for 24 hours.

8. After that, geopolymer concrete is released from the mold and put into the oven at 23°C over the life of the testing that has been established (14 and 28 days).

4.8.Slump Test

The aim of the test is to assess the free flow of geopolymer concrete mix into the horizontal direction without hindrance. This test also intends to determine the workability in the process of geopolymer concrete mix.

How to test Slump

1. Put the mixture into the Abrams funnel cone in 3 layers. For each layer, pound the mixture for 25 times.

2. After flatten the upper surface of the mixture keep it for approximately 1 minute.

3. Lifted the Abrams cone vertically.

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4.9.Curing Process

Curing process is done by put the mixture with the mold into the oven at 80° C for 24 hours. The aim of this step is to keep the temperature of geopolymer concrete constant in the medium heat because polymerization reaction needs medium heat during the curing. From the chemical reaction, geopolymer concrete will produces water that will be removed during the curing process. Therefore, after remove the mixture from the oven and mold, geopolymer concrete directly put into the oven at temperature 23°C. So the environment does not affect the process of concrete geopolimer condensation.

4.10. Compressive Strength and Modulus of Elasticity Tests

Concrete compressive strength and modulus of elasticity testing were

conducted at the Building Material’s Laboratory of Civil Engineering Program, Faculty of Engineering, Universitas Atma Jaya Yogyakarta. Tests carried out using Compression Testing Machine (CTM) with brand ELE.

4.11. Schedule of the Final Project

The research should be scheduled to make sure that the research can be done on time. The schedule of the research can be seen in Table 4.2

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Table 4.2. Schedule of the Research

Activity

2014-2015

September October November January February March Determine the

topic of the final project Wrote the

proposal Seminar Proposal Implementation

Research and Data Analysis Wrote the final

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CHAPTER V

DISCUSSION

5.1.Result and Discussion of material Investigation

5.1.1. Investigate the Fine Aggregate to Obtain the Results.

1. Investigation of the organic matter content.

Investigate the organic matter content is important because the organic matter content can reduce the quality of the concrete. To know whether it is possible to be used or not can be seen from the color of the sample. The relationship between the color and possibility of fine aggregate can be seen from Table 5.1.

Table 5.1 Relationship between the Color of the Solution and Organic Mater Content

No. Color Organic Mater Information

5 Light flaxen Less organic matter

content Good to be used 8 Flaxen

Rather much organic matter

content

Can be used

11 Dark Yellow

A lot of organic

matter content Not really good to be used

14 Dark Orange

A lot of organic

matter content Cannot be used 16 Dark Red A lot of organic

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(5-1) After the sand washed using NaOH 3% and kept for 24 hours, the solution is appropriate with the color of Gardner Standard Color No. 8 so that the sand can be used for the experiment.

2. Investigate the amount of mud in sand

Fine aggregate should not contain of mud until 5% greater than the density of dry oven. If the mud levels exceed 5%, the fine aggregate should be washed because the high value of mud can reduce the bind between fine aggregate and geopolymer paste. So, the quality of the concrete can be bad. The value of the investigation can be seen in Table 5.2.

Table 5.2 Investigation of Mud in the Sand.

Investigation weight (gram)

Weight of sand

(A) 99

So, the amount of mud in the sand can be calculated as follow:

with:

W= the amount of the mud in the sand

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Based on SK SNI S-04-1989-F, fine aggregate cannot have the amount of mud more than 5%. If the mud is more than 5% so that the fine aggregate should be washed because the high content of mud will decrease the bond between sand and paste and it makes the quality will decrease.

3. Density and Absorption

The result of the density and absorption test of fine aggregate can be seen in table 5.3.

Table 5.3 Result of the Density and Absorption Test of Fine Aggregate

Information Value

A Dry Weight Sample 500 gram

B Weight Sample (SSD) 178

C Weight of Sample from the Oven 482,13 gram D Bulk Density =

2,712

E Bulk Density SSD =

2,812

F ApparentDensity =

3,001

G Absorption=

3,701%

The fine aggregate is restrained in the sieve no. 4 (4.75mm). The weight of the sample is 500gr. From the requirement, the density of the fine aggregate for the normal concrete is around 2.4-3.2 gr/cm3. The density of this test is

59

2.712%. So the sand can be used in the geopolymer concrete. The absorption of the split is 3.701%

4. Water Content

The water content test of fine aggregate is equal to 1.6635 %. The calculation of the water content of fine aggregate can be seen in appendix A.3

5.1.2. Investigate the Coarse Aggregate to Obtain the Result

1. Investigation of the organic matter content.

Coarse aggregate shall not contain the mud 1% greater than the density of dry oven. If the mud levels exceed 1%, the coarse aggregate should be washed, because of the high levels of mud would reduce bond coarse aggregate in the concrete mix. The investigation value of the mud in coarse aggregate can be seen in Table 5.4.

Table 5.4 Investigation of Mud in the Coarse Aggregate

Investigation Weight

(gram)

Weight of coarse aggregate

(A) 99.3

So, the amount of mud in the sand can be calculated as follow:

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with:

W= the amount of the mud in the coarse aggregate

A = the weight of coarse aggregate after dried in the oven

The amount of mud in coarse aggregate is <1% so that the coarse aggregate can be used as the material of the specimen.

2. Density and Absorption

The result of the density and absorption test of coarse aggregate can be seen in table 5.5.

Table 5.5 Result of the Density and Absorption Test of Coarse Aggregate

Information Value

A Dry Weight Sample 500 gram

B Weight Sample (SSD) 505 gram

C Weight of Sample in the Water 293,5 gram

D Bulk Weight Density

) ( ) ( ) ( C B A   2,3711

E Bulk Weight Density (SSD)

) ( ) ( ) ( C B B   2,3948

F Weight Density (Apparent)

) ( ) ( ) ( C A A   2,4289

G Absorption x 100% ) ( ) ( ) ( A A B   1%

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The coarse aggregate is restrained in the sieve no. 4 (4.75mm). The weight of the sample is 500gr. From the requirement, the density of the coarse aggregate for the normal concrete is around 2.4-3 gr/cm3. The density of this test is 2.3711%. So the coarse aggregate can be used in the geopolymer concrete. The absorption of the coarse aggregate is 1%

3. Water Content

The water content test of coarse aggregate is equal to 1,342%. The calculation of the water content of coarse aggregate can be seen in appendix A.4

5.2.Slump Test

Slump test was conducted to measure the ease slump concrete mix to be done (workability). Implementation procedures described in Chapter IV. The Value of slump was affecting the strength of the concrete. The big value of slump will produce a bad concrete because it can produce a porous concrete. If the value of the slump is too small the concrete will be difficult to be mixed. The tests carried out per variant slump value at age 14 and 28 days. Slump Test results is shown in the table 5.6

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Table 5.6 The Result of Slump Test at 14 days and 28 days

Varian

Slump Value (14 days)

Slump Value (28 days)

Metakaolin : Silica Fume (cm)

75:5 0 0

50:5 0 0

25:10 2 0

The differences value in the experiment is because the amount of additional water to make the mixture is easy to be done. If the amount of additional water is high the mixture will be too wet and the value of the test will be higher.

5.3.Weight Density of Concrete

The types of concrete can be grouped based on the weight of the concrete type. Concrete grouping based on its density can be seen in Table 5.7.

Tabel 5.7 Specification of Weight Density of Concrete

Type Weight Density

(gr/cm3) Usage

Very Lightweight

Concrete <1,00 Non Struktur Lightweight Concrete 1,00-2,00 Lightweight

Structure Normal Concrete 2,30-2,50 Structure Weight Concrete >3,00 Light shield

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In this research, the age of the concrete is divided into two types; 14 days and 28 days. In day 14, the highest value of the density is in the percentage of both metakaolin and silica fume as much as 25:5. The value is 1.9519 gr/cm3. The complete value can be seen in Table 5.8 and the chart can be seen in Figure 5.1.

Tabel 5.8 Average Weight Density in 14 days Pozzolan Weight Density

(gr/cm3)

Average of Weight Density (gr/cm3) Metakaolin : Silica Fume

25:5 1.9757 1.9519 1.9381 1.9419 50:5 1.8706 1.8974 1.8929 1.9288 75:5 1.7608 1.7176 1.6988 1.6932 Figure 5.1 Weight Density in 14 Days Chart

1,6000 1,6500 1,7000 1,7500 1,8000 1,8500 1,9000 1,9500 2,0000

25:5 50:5 75:5

W e ig h t D e n si ty ( g r/ cm 3 )

Precentage of Metakaolin and Silica Fume (%)

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In day 28, the highest value of the density is in the percentage of both metakaolin and silica fume as much as 25:5. The value is 1.9287 gr/cm3. The complete value can be seen in Table 5.9 and the chart can be seen in Figure 5.2.

Tabel 5.9 Average Weight Density in 28 days Pozzolan _{Weight Density}

(gr/cm3)

Average of Weight Density (gr/cm3) Metakaolin : Silica Fume

25:5 1.8616 1.9287 1.9902 1.9344 50:5 1.7159 1.8051 1.8512 1.8483 75:5 1.6783 1.6939 1.7351 1.6683

Figure 5.2 Weight Density in 28 Days Chart

1,5500 1,6000 1,6500 1,7000 1,7500 1,8000 1,8500 1,9000 1,9500

25:5 50:5 75:5

W e ig h t D e n si ty ( g r/ cm 3 )

Precentage of Metakaolin and Silica Fume (%)

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The value of weight density is depends on the sample. It is because of the process of the compaction from the sample itself. Based on the table above, weight density of the geopolymer concrete is belongs to lightweight concrete. The biggest value of the average weight density of concrete comes from the geopolymer concrete with the proportion of the metakaolin and silica fume; 25:5 in 14 days. The value is 1.9519 gr/cm3

5.4.Compressive Strength of Concrete

Compressive strength test is done at the age of 14 days and 28 days. The test is done by machine (UTM) with Shimadzu brands. The test results from the small cylinder (day 14) are already change into the normal size of the concrete (150 mm x 300 mm). The compressive strength value of the research can be seen in Table 5.10 and the chart of compressive strength test can be seen in Figures 5.3 and 5.4.

Table 5.10 Compressive Strength Test

Pozzolan Compressive Strength (Mpa)

Metakaolin Silica Fume 14 days 28 days

25% 5%

2.30729

2.071743

1.10814

1.149566

2.02273 1.20311

1.88520 1.13744

50% 5%

1.37959

1.229189

0.68563

0.641213

1.21979 0.61374

1.08817 0.62426

75% 5%

0.69916

0.675865

0.15911

0.178246

0.63963 0.19685

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Figure 5.3 Compressive Strength Column Chart

Figure 5.4 Compressive Strength Line Chart

Based on the test, the highest value of the compressive strength is 2.071743 MPa in day 14 with the ratio of metakaolin and silica fume as much as 25:5. From the test, it is known that the highest proportion of metakaolin, the lowest value of the test.

0 0,5 1 1,5 2 2,5

25% : 5% 50% : 5% 75% : 5%

C o m p re ss iv e S tr e n g th V a lu e (M P a )

Precentage of Metakaolin and Silica Fume (%)

14 days 28 days 0 0,5 1 1,5 2 2,5

25% : 5% 50% : 5% 75% : 5%

C o m p re ss iv e S tr e n g th V a lu e (M P a )

Precentage of Metakaolin and Silica Fume (%)

14 days 28 days

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The value of the mixture should be higher because both metakaolin and silica fume have higher percentage of SiO2 (Silica) and both of them also contain of Calcium Oxide (CaO). CaO will has a reaction with NaOH become Ca(OH)2. SiO2 will be react with Ca(OH)2 become Calcium Silicate Hydrate (CSH) that will be used as a paste. The mixture should be strong enough. Na2SiO3 also used as alkali of the geopolymer. The Na2SiO3 will react with NaOH and make a strong binder.

From the result, the values of the concrete are very low. According to the author, the values are low because they do not have a good proportion of CaO. So, the reaction is not properly. From the table below, it is known that all of the materials only have a good proportion in Silica, but not in Calcium Oxide while the composition of CaO in cement is really big; 64.67%. The composition of the contents can be seen in Table 5.11.

Table 5.11 Composition of the Contents

Content Name cement Metakaolin Silica Fume

SiO2 Silica 21.03% 66.39% 85%

CaO Calcium Oxide 64.67% 3.08% <1

Fe2O3 Iron Oxide 2.58% 5.00% -

MgO Magnesia 2.62% 9.64% -

Na2O Alkali 1.34% 2.97% 8,72%

5.5.1. Research Comparison

Research comparison is used to show the effect of the material in the concrete. Every research has its own result that depends on the material preparation,

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temperature, type, and environment. This research will be compared with the research from Lisantono and Hatmoko (2009) that also use metakaolin and bagasse ash as the materials. The tables of the comparison value can be seen in table 5.12 and table 5.13.

Table 5.12 Compressive Strength of the Test

Combustion of Metakaolin Time (minute) Molarity of NaOH

Pozzolan Compressive Strength (Mpa)

800°C 40 min’ 12M

Metakaolin Silica

Fume 14 days 28 days

25% 5%

2.307

2.071

1.108

1.149

2.022 1.203

1.885 1.137

50% 5%

1.379

1.229

0.685

0.641

1.219 0.613

1.088 0.624

75% 5%

0.699

0.675

0.159

0.178

0.639 0.196

0.688 0.178

Table 5.13 Compressive Strength of Lisantono and Hatmoko Research

Combustion of Metakaolin Time (minute) Molarity of NaOH

Pozzolan Compressive Strength (Mpa)

500°C 25 min’ 8M

Metakaolin Bagasse

Ash 14 days 28 days

50% -

0.715

0.560

0.759

0.721

0.467 0.507

0.497 0.898

50% 50%

0.427

0.380

0.720

0.852

0.473 0.950

0.239 0.886

- 50%

0.336

0.325

0.366

0.344

0.425 0.329

0.213 0.336

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Based on the comparison, the highest value of the compressive strength in this research is 2.071 MPa in day 14 with the ratio of metakaolin and silica fume as much as 25:5. The highest value of the compressive strength in Lisantono and Hatmoko (2009) research is 0.852 MPa in day 28 with the materials are metakaolin and bagasse ash. The tables show that the temperature of combustion, time of combustion and molarity of NaOH of both researches are different. That can be one of the reasons why the values of both researches are different. From the result of Lisantono and Hatmoko (2009), the highest proportion is in the metakaolin and bagasse ash in day 28. But, in day 14 the highest value is in the proportion of 50% of metakaolin. The lowest value of the result in Lisantono and Hatmoko (2009) is in the result from the bagasse ash. The values are 0.325 MPa in 14 days and 0.344 MPa in 28 days. There will be an effort how to increase the compressive strength of geopolymer concrete based on metakaolin. But, according to the theories and researches from the other researchers, metakaolin should be strong material from concrete.

5.5.Modulus Elasticity of Concrete

The result of modulus of elasticity is depends on the composition of the mixture. In this research the result of the modulus of elasticity can be seen in the table 5.14 and the average of modulus of elasticity value can be seen in Table 5.15.

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Table 5.14 Modulus of Elasticity Test

Concrete

Area (Ao)

Average of

Area Po

Maximum load

Average of

Compression Average

Average of strain E

(cm2) (kgf) (Mpa) (Mpa) (Mpa)

25:5

172.5683

172.5683

21.34 725 0.2131

0.2001

0.0659 3.234

171.1738 20.91 675 0.2115 0.0786 2.691

170.7103 21.04 625 0.1867 0.0698 2.675

50:5

171.6380

171.6380

20.41 625 0.1857

0.1636

0.0719 2.583

172.5683 21.34 500 0.1491 0.0643 2.319

172.8013 20.91 525 0.1560 0.0705 2.213

75:5

172.5683

172.5683

20.32 150 0.0497

0.0673

0.0552 0.900

171.8704 20.93 275 0.0885 0.0714 1.239

172.8013 20.92 200 0.0638 0.0495 1.289

Table 5.15 Average of Modulus of Elasticity Test

Modulus of Elasticity Average Modulus of Elasticity

(Mpa) (Mpa)

3.234 2,866 2.691 2.675 2.583 2.371 2.319 2.213 0.900 1.143 1.239 1.289

From the result, the highest maximum load is in the mixture with the proportion of metakaolin and silica fume; 25% : 5%. The value of compression strength test is 0.2131 MPa with the value of strain is 0.0659 and the value of

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modulus of elasticity is 3.234 MPa. The highest value of strain is in the proportion of metakaolin and silica fume; 50:5. The value is 0.0719 and the value of modulus elasticity is 2.583 MPa. The highest value of modulus of elasticity is in the proportion of metakaolin and silica fume; 25% : 5%. The value is 3.234 MPa.

Based on modulus of elasticity test that has been done, the value of the average of modulus of elasticity at 28 days with comparative precursor are metakaolin and silica fume are 25% :5% = 2.866 MPa, 50% :5% = 2.371MPa, 75% : 5% = 1.143 MPa. The modulus of elasticity chart can be seen in Figure 5.6.

Figure 5.6 Modulus of Elasticity Chart

0,000 0,500 1,000 1,500 2,000 2,500 3,000 3,500

25:5 50:5 75:5

M o d u lu s o f E la st ic it y V a lu e ( M P a )

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CHAPTER VI

CONCLUSION AND SUGGESTION

6.1.Conclusion

From the test of compressive strength and modulus elasticiy:

1. The difference in the value of the slump caused by the condition of the mixture and the workability. If the condition of mixture is wet so the workability will be ease to work but the slump is big. If the condition of mixture is hard so the workability will be difficult to work but the slump is small.

2. The value of concrete density is determined by the manufacturing process, in this case the compaction process.

3. Based on compression strength test that has been done, the value of the average compressive strength at 28 days with comparative precursor (metakaolin:silica fume) 25:5, 50:5, 75:5 are 1.149MPa, 0.641 MPa and 0.178 MPa

4. The maximum concrete compressive strength occurred on geopolymer concrete with the composition of metakaolin is of 25%. 5. The compressive strength of the concrete is affected by the condition

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6. The combustion of the metakaolin and molarity of the NaOH can affected the geopolymer concrete. Because, the differences of component also make the binder is different.

7. Based on modulus of elasticity test that has been done, the value of the average modulus of elasticity at 28 days with comparative precursor (metakaolin:silica fume) 25:5, 50:5, 75:5 are 7.781 MPa, 2.371 MPa and 1.143 MPa

8. The greater the result, the smaller value of the stretch. So, if the value of the modulus of elasticity small it is mean that the concrete is easy to get shorten or extension.

9. Geopolymer concrete with metakaolin and silica fume cannot be used as any structural concrete but actually if the proportion between metakaolin and alkali activator is mixed properly the result can be better. In this research, the highest compressive strength at 28 days of 2.071743 MPa.

6.2.Suggestion

From the research that has been done can be given advice that is expected to be useful. Advice can be given as follows.

1. Try to aggregate conditions used really SSD.

2. For further research, the mix design about proportion of metakaolin and activator can be regenerate. So, the proportion will be mixed properly and make a strong binder.

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3. The combustion of the metakaolin will be better in 500°C-800°C 4. Molarity of NaOH will be better in 12M. because the concentrate of

NaOH will be strong enough for bind the materials.

5. Concrete can be tested by adding some material which has the value of lime (CaO) is high or just add the lime (CaO) as the pozzolan composition. So, there wil be a reaction between Ca(OH)2 and SiO2 that will produce (CSH) as an adhesive.

6. Keep the compaction process of each sample is done consistently so that the value of the weight density can be more consistent

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B.1. MIX DESIGN FOR BIG CYLINDER (150mm X 300mm)

calculation of sample Cylinder

diameter (d) = 150 mm

height (t) = 300 mm

volume (1 cylinder) = 0.25*22/7*d^2*t

= 5303571.429 mm^3

= 0.005303571 m^3

wet density of concrete

= 1900 kg/m^3

density of concrete (1 concrete) = vol*wet density

= 10.07678571 kg

= 10076.78571 gram

Pozzolan

Metakaolin 25% = 2519.196429 gram

Silica Fume 5% = 503.8392857 gram

Metakaolin 50% = 5038.392857 gram

Silica Fume 5% = 503.8392857 gram

Metakaolin 75% = 7557.589286 gram

Silica Fume 5% = 503.8392857 gram

AGGREGATE AND ALKALI ACTIVATOR

Precentage of Aggregate and Alkali Activator = 3:1

Aggregate = 3/4*density of concrete

= 7557.589286 gram

Alkali activator = 1/4*density of concrete

= 2519.196429 gram

Aggregate

Coarse Aggregate and Fine Aggregate = 2:1

Coarse Aggregate = 2/3*aggregate

= 5038.392857 gram

Fine Aggregate = 1/3*aggregate

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Alkali Activator

NaOH 12M + Na2SiO4 2:1

NaOH 12M = 2/3*alkali activator

= 1679.46 gram

Na2SiO4 = 1/3*alkali activator

= 839.73 gram

NAOH

Mol NaOH = 40 g/mol

NaOh 12 M =

(12*40)+1000 ml aguades

NAOH 12 M : Distilled Water = 480 : 1000

NaOh 12 M = 480/1480*NaOH 12M

544.69 gram

Distilled Water = 1000/1480*NaOH 12M

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C. WEIGHT DENSITY

C.1. AVERAGE WEIGHT DENSITY IN 14 DAYS

Pozzolan

Weight Density

(gr/cm

3

)

Average of Weight

Density

Metakaolin : Silica Fume

25:5

1.9757

1.9519

1.9381

1.9419

50:5

1.8706

1.8974

1.8929

1.9288

75:5

1.7608

1.7176

1.6988

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Pozzolan

Weight Density

(gr/cm3)

Average of Weight

Density

Metakaolin : Silica Fume

25:5

1.8616

1.9287

1.9902

1.9344

50:5

1.7159

1.8051

1.8512

1.8483

75:5

1.6783

1.6939

1.7351

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D. COMPRESSIVE STRENGTH TEST

Pozzolan Compressive Strength (Mpa) Metakaolin Silica Fume 14 days 28 days

25% 5%

2.30729

2.071743

1.10814

1.149566

2.02273 1.20311

1.88520 1.13744

50% 5%

1.37959

1.229189

0.68563

0.641213

1.21979 0.61374

1.08817 0.62426

75% 5%

0.69916

0.675865

0.15911

0.178246

0.63963 0.19685

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E. MODULUS OF ELASTICITY TEST

Concrete Area (Ao)

Average

of Area Po

Maximum load

Average of

Compression Average

Average of strain E

(cm2) (kgf) (Mpa) (Mpa) (Mpa)

25:5

172.5683

172.5683

21.34 725 0.2131

0.2001

0.0659 3.234

171.1738 20.91 675 0.2115 0.0786 2.691

170.7103 21.04 625 0.1867 0.0698 2.675

50:5

171.6380

171.6380

20.41 625 0.1857

0.1636

0.0719 2.583

172.5683 21.34 500 0.1491 0.0643 2.319

172.8013 20.91 525 0.1560 0.0705 2.213

75:5

172.5683

172.5683

20.32 150 0.0497

0.0673

0.0552 0.900

171.8704 20.93 275 0.0885 0.0714 1.239

172.8013 20.92 200 0.0638 0.0495 1.289

Modulus of Elasticity Average Modulus of Elasticity

(Mpa) (Mpa)

3.234 2.866 2.691 2.675 2.583 2.371 2.319 2.213 0.900 1.143 1.239 1.289