Evaluation of the Characteristic of Heavyweight Concrete .... Appl. Environ. Biol. Sci., 1... · Ristinah S. et al., 2011 Figure 1. The rate of attenuation of thick concrete [3] Steel

J. Appl. Environ. Biol. Sci., 1(11)512-521, 2011

© 2011, TextRoad Publication

ISSN: 2090-4215 Journal of Applied Environmental

and Biological Sciences www.textroad.com

*Corresponding Author: Ristinah S., Wisnumurti, Ludfi Djakfar Department of Civil Engineering, Faculty of Engineering, University of Brawijaya, Indonesia. E. mail: [email protected]

Evaluation of the Characteristic of Heavyweight Concrete using Steel Slag Aggregates for Radiation Shielding

Ristinah S.*, Wisnumurti, Ludfi Djakfar

Department of Civil Engineering, Faculty of Engineering, University of Brawijaya, Indonesia

ABSTRACT

This research was conducted to evaluate the properties of heavyweight concrete using steel slag particularly on shielding radiation properties. To achieve the objective, as many as 9 samples having dimension of 30 x 30 cm, with thickness varied of 5, 9 and 13 cm were tested. The evaluation includes: density, compressive strength, and the coefficient of attenuation. For comparison purposes as many as 9 normal concrete samples having similar dimension were also tested. The results showed that the density of heavyweight concrete was 3272 kg/m3, while the normal concrete was 2311 kg/m3. The results of attenuation experiment showed that the attenuation coefficient for heavyweight concrete was 1.5 times higher than that of normal concrete. The thicker the wall, the higher the capacity of shielding radiation X-RD analysis before and after radiation showed that gamma radiation effected the atomic structure but did not influence to the properties of concrete. But the result of SEM was not conclusive when measuring the effect of the radiation to the microstructure of heavy weight concrete. Key words: Steel slag, heavy weight concrete, radiation, and attenuation

INTRODUCTION In order to fulfill energy demands, nuclear power to generate electricity into an alternative energy source after water, coal, petroleum, geothermal, wind and solar. Nuclear reactors are the main source of radiation which produced when fission reaction mostly radioactive. On the other side the dangers of radiation x-rays, γ-rays, neutrons and other rays which threaten human health and safety, so it required protection system that is able to resist radiation which generated during operation. Material which choosen for radiation protective must have the appropriate properties of SKSNI-T 04-1989F Mehta et al [1], concrete is a good radiation protector material because it has the characteristics which necessary to weaken the γ rays and neutrons. Because concrete is a mixture of hydrogen and other light core element and the core element of an element that has a large atomic number (iron) and can be produced with varying density. The use of concrete for radiation shield is more focused on the nuclear requirements, not strength. Medium quality concrete enough to fullfill the strength of radiation shield but the concrete must with high density so it can better resist the radiation . Quantity of material radiation including: 1). Ratio of rate exposure is the ratio of number of photons after passing through thickness of protection material with the number of initial photons; 2). Coefficient of attenuation is microscopic latitudes side, while the physical meaning of the latitudes sides (Cross section) is the probability to absorb or scatter radiation Muhammah Abduh [2], concluded that the higher the density (unit weight) the higher the compressive strength of concrete. The ability of attenuation against radiation with the energy of 0661 MeV can be improved by increasing the density of concrete. High quality polymer concrete is a material that is light enough, strong and good in terms of structure as γ radiation protection 1.5 times greater attenuation of high quality concrete with fly ash and 1.6 times greater attenuation normal concrete.

Dwiyatmoko Y [3], concluded that increasing age does not affect the concrete's ability to absorb neutron radiation. Neutron radiation intensity decreases (exponentially) with increased wall thickness of radiation shielding. Concrete with stone aggregate having a density of 2800-3000 kg/m3 have the ability to resist neutron radiation is not better than normal concrete with a density of 2400 kg/m3.

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Ristinah S. et al., 2011

Figure 1. The rate of attenuation of thick concrete [3] Steel slag which has an uneven surface structure and has prismatic shape have the heavy volume of 1600-1920 kg/m3, specific gravity and water absorption 3.2-3.6 to 3%. The main compound of steel slag are crystalline compounds such as silicate dicalcium, tricalcium, dicalcium ferrite, merwinite, calcium magnesium iron, oxide, some free lime and free magnesia. Steel slag is cementitous material which containing cement binder, so steel slag has good mechanical properties to be mixed agregat for concrete. By considering good physical and mechanical properties then by taking steel slag material as steel waste from steel mill PT. ISPAT INDO Surabaya make an appropriate mixing design for heavy concrete and performed testing both physical and mechanical properties. In this study the behavior of concrete will be evaluated of the radiation, the molecular structure with SEM (Scanning Electron Microscope) and the crystal structure by x-ray diffraction method

METHODOLOGY

Flowchart of research The steps of this research was dued to the flowchart below.

Location of research a. Testing the physical and mechanical properties of concrete in Construction Materials

Laboratory, Department of Civil Engineering, and Faculty of Engineering University of Brawijaya.

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b. Testing of radiation, diffraction done in BATAN Nuclear Research Center in Bandung. c. SEM testing performed in laboratories Metallurgy Department of Mechanical Engineering

Faculty of Industrial Technology, ITB. Research equipment

Equipments which used in these research are as follow: Physical and mechanical properties of concrete test

a. Sources of radiation equipment Gamma rays with energy of 0661 MeV, the tools used: Baby line 81 types E-443, the standard sources: Cs-137, Distance sources: 55 cm

c. Experimental x-ray diffraction equipment (X-RD) was used tool SHAMADZU recording X-ray Diffract meter model AD-3A

d. Experimental equipment SEM (Scanning Electron Microscope), a tool used is the Philips type XL: 20 + EDS (Energy Disperse Spectroscopy) with 80 000 times magnification.

Material of research

Material of research are as follow: a. Steel slag b. Natural sand and crushed stone c. Gresik cement type I d. Water PDAM Malang

Experimental Design Experimental design and number of test specimens for this research is shown in Table 1.

Table.1.Experimental Design

Data collection The data collected aws as follow:

a. Physical properties and mechanical concrete: aggregate gradation, specific gravity, absorption, unit weight (density), slump, compressive strength, split tensile strength, modulus of elasticity and Poisson's ratio.

b. Radiation of the concrete: effective attenuation coefficient, effective mass attenuation coefficient, the effect of radiation of the micro-structure (SEM), the shape of the crystal structure (x-ray diffraction).

c. Data were analyzed to determine the effect of wall thickness on the ability to absorb radiation, to know the difference between heavy concrete from steel slag and normal concrete with natural aggregates on the ability to absorb radiation.

RESULTS AND DISCUSSION

Physical and mechanical properties of concrete The results of testing the physical properties of aggregates for heavy concrete from steel slag and normal concrete from fine aggregate (natural sand), coarse (crushed stone) obtained the following data:

Note: t = thickness = 5, 9, 13 cm

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Table 2 Physical properties of aggregate Parameter Value Standard/Information

Spesific gravity of fine agregate a. Steel slag b. Natural sand

3.861 2.621

ACI 211.1-91 (3.4-3.8) ASTM C 128 (1.6-3.2)

Spesific gravity of coarse agregate a. Steel slag b. Natural sand

3.364 2.938

ACI 211.1-91 (3.4-3.8) ASTM C 128 (1.6-3.2)

fine agregate adsorbtion a. Steel slag b. Natural sand

0.120%

1%

ASTM C 128 (0.2-2%)

Coarse agregate adsorbtion a. Steel slag b. Natural sand

2.0827% 2.3801%

ASTM C 127 (0.2-4%)

Unit weight of agregate a. Steel slag b. Natural sand

2083.347 kg/m3 1643.307 kg/m3

Heavy agregate Normal agregate

With the physical properties of aggregate data as above is made mix design based on the

ACI 211.1-91, sieving C 637-90 and ASTM C 33 as well as variations in aggregate cement ratio (A / C) and water cement factor (FAS) is obtained the following results: Table 3 Mechanical Property

Kind of concrete

Variation A/C

Unit Weight (kg/m3)

Compressive strength (kg/cm2)

Split tensile strength (kg/cm2)

Modulus Of Elastisity

(MPa)

Poisson’s Ratio

1. Heavy concrete A C 637-90

1 : 4.5 1 : 5

1 : 5.5 1 : 6

2939 2953 3048 3064

146.495 202.204 269.550 214.997

- - - -

- - - -

2.Heavy concrete B

C 33

1 : 6 FAS 0.5

1 : 6 FAS 0.55

1 : 6 FAS 0.6

3140

3220

3272

261.710

235.943

175.051

- -

31.26

- -

40968.91

0.2995

3.Normal concrte C

C 33

1 ; 6 FAS 0.6 2311 176.124 12.04 24202.62 0.2477

The properties of nuclear

Attenuation of Radiation: The test results performed on the rate of exposure to the test object with a thick 5, 9 and

13 cm for heavy concrete and normal concrete can be seen in Table 4 and Figure 2. Table 4. Thickness and ratio of rate expossure

No. Thickness (cm)

Ratio of rate expossure Heavy concrete

(X/Xo)

Ratio of rate expossure Normal concrete

(X/Xo) 1 5 0.234567901 0.413580247 2 9 0.175308642 0.329629630

3 13 0.090123457 0.231481481

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y = 0,6071e-0,0725x

R2 = 0,9844

y = 0,4539e-0,1196x

R2 = 0,9515

0

0,05

0,1

0,15

0,2

0,25

0,3

0,35

0,4

0,45

0 2 4 6 8 10 12 14Ketebalan (cm)

Ras

io L

aju

Pap

aran

BETON BERAT BETON NORMALExpon. (BETON NORMAL) Expon. (BETON BERAT)

Figure 2. Thickness vs Ratio of rate expossure

Obtained from regression analysis of exponential regression equation as follows: Heavy concrete :Y = 0.4539e-0.119 ; R2= 0.9515

Normal concrete:Y = 0.6071e-0.0725x ; R2= 0.9844

Note: Y = the ratio of the rate of exposure, X = thickness (cm) From the figure it can be seen that the curves of heavy concrete under the normal concrete curve, this suggests that the heavy concrete absorb more radiation than normal concrete. Directly it can be concluded that the effective attenuation coefficient heavy concrete of the graph would be higher than normal concrete. The relationship between types of concrete with thickness variation and the effective attenuation coefficient can be seen in Table 5. From the analysis of variance obtained the conclusion that the use of variations in wall thickness of heavy concrete and normal concrete impact the effective attenuation coefficient. The thicker the wall the greater the wall can absorb radiation in both concrete and normal concrete weight. The relationship between the thickness and the effective attenuation coefficient was shown in figure 3. Table 5. Effective attenuation coefficient

y = 0,2238e-0,0563x

R2 = 0,8942

y = 0,3664e-0,0572x

R2 = 0,8211

0,06

0,11

0,16

0,21

0,26

0,31

0 2 4 6 8 10 12 14

Ketebalan (cm)

Koe

fisie

n At

tenu

asi E

fekt

if ( /

cm )

Beton Berat Beton Normal

Figure 3. Relationship between thickness and attenution coefficient

Regression analysis between the variation of the thickness and attenuation coefficient

obtained by exponential regression equation as follows:

Type of concrete Effective attenuation coefficient (/cm)

B1-5 0.29276

B2-9 0.19351

B3-13 0.18521

N1-5 0.17662

N2-9 0.12332

N3-13 0.11263

r a t i o o f d r i v e

Weight concrete Normal concrete

thickness (cm)

Normal concrete Weight concrete

Weight concrete

Normal concrete

Thickness (cm)

e f f a t t e n u a l c o e f

cm \\\

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1. For steel slag heavy concrete Equation Y = 0.3664 e - 0,0572 X

Determination coefficient (R2) = 0.8211; Corelation coefficient (R) = 0. 9061 2. For normal concrete natural agregate Equation Y = 0.2238 e - 0,0563 X

Determination coefficient (R2) = 0. 8942; Corelation coefficient (R) = 0.9456 The relationship between the weight of the volume (density) with an effective attenuation coefficient and the effective mass attenuation coefficient can be seen in Table 6 and Figure 4, 5, 6.

Table 6 the relationship between weight and volume of effective attenuation coefficient and effective mass attenuation coefficient

Type of concrete Unit Weight (gr/cm3)

Efective attenuation coefficient ( / cm )

Effective Mass Attenuation Coefficient (cm2/g)

B1-5 3.2814815 0.16041 0.0893

B2-9 3.2386831 0.14250 0.0592

B3-13 3.2222222 0.12332 0.0578

N1-5 2.3925926 0.12015 0.0752

N2-9 2.3168724 0.11472 0.0532

N3-13 2.3304843 0.11260 0.0483

y = 1,9161x - 5,9987R2 = 0,9593

0,06

0,11

0,16

0,21

0,26

0,31

3,21 3,22 3,23 3,24 3,25 3,26 3,27 3,28 3,29

Berat Volume (gr/cm^3)

Koe

fisie

n At

tenu

asi E

fekt

if ( /

cm )

Beton Berat

Figure 4. The relationship between unit weight of heavy concrete

and effective attenuation coefficient

y = 0,8047x - 1,7507R2 = 0,8972

0,060,080,1

0,120,140,160,180,2

2,3 2,32 2,34 2,36 2,38 2,4

Berat Volume (gr/cm^3)

Koe

fisie

n At

tenu

asi E

fekt

if ( /

cm )

Beton Normal

Figure 5. The relationship between unit weight of normal concrete and effective attenuation coefficient


cm \\\

Volume wwight (gram/cm3)

Weight concrete


cm

Volume wwight (gram/cm3)

Normal concrete

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y = 0,0951e-0,0553x

R2 = 0,9048

y = 0,0944e-0,0413x

R2 = 0,8048

00,010,020,030,040,050,060,070,080,09

0 2 4 6 8 10 12 14

Ketebalan (cm)Ko

efis

ien

Atte

nuas

i Efe

ktif

Mas

sa

(cm

^2/g

r )

Beton Berat Beton Normal

Figure 6. Relation between thickness and effective attenuation coefficient mass

From regression analysis we can obtained relationshipwith linear equation as follow : Heavy concrete Y = 1.9161 X -5.9987; R2= 0.9593 Normal concrete Y = 0.8047 X -1.7507 R2= 0.8972 Note: Y = Effective attenuation coeficcient ( /cm) X = Unit weight (density) concrete (gr/cm3) From the figure can be seen that the higher the density of the concrete the higher the effective attenuation coefficient, both for heavy concrete and normal concrete. Heavy concrete attenuation coefficient values higher than normal concrete. So it can be said that the heavy concrete has better attenuation properties than normal concrete. Corelation between thickness and effective mass attenuation coefficient obtained by exponential equation as follows: 1. For steel slag heavy concrete

Equation Y = 0.0944 e - 0,0413 X Determination coefficient (R2) = 0.8048; Corelation coefficient (R) = 0.897106

2. For normal concrete natural agregate Equation Y = 0.0951 e - 0,0553 X Determination coefficient (R2) = 0.9048; Corelation coefficient (R) = 0.95121

Figure 7. Weight of Concrete difractogram before radiation

m a s s e f f a t t e n u a l c o e f

Thickness (cm)

Normal concrete

Weight concret

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X-ray diffraction (X-RD) Recorder output in the form of a diffraction pattern or difractogram is the relationship between the intensity of the diffraction angle 2θ as described as in Figure 7 and Figure 8.

Figure 8. Weight of Concrete difractogram after radiation

The position of diffraction angles describe the type of crystal, intensity can represent the concentration of crystal and a sample rate of crystal. Samples with high crystal rate even though the numbers are low; it will give a high intensity and sharp. Analysis of peaks of heavy concrete difractogram was shown as in Table 7 below.

Table 7.Peak difractogram concrete analysis 1. Before Radiation

Peak No. 2 dhkl

Prediction of compounds

Crystal Structure

5 29.6 3.01534 Ca2Si2O7 Monoklinik 6 32.6 2.74438 MgCO3 atau Ca2SiO4 Trigonal

7 33.0 2.71020 Ca2SiO4 atau CaMn2O4 Orthorombik

8 35.6 2.51968 Mg2SiO4 Orthorombik 9 36.6 2.46612 Mg2SiO4 Orthorombik 12 42.4 2.12998 Al2O3 Monoklinik

13 43.2 2.09238 Mg2PO2O7 Trigonal

2. After Radiation

Peak No. 2 dhkl Prediction of compouns Crystal Structure

2 29.6 3.01534 Ca2Si2O7 Monoklinik 4 32.6 2.74438 MgCO3 atau Ca2SiO4 Trigonal

5 34.4 2.60478 (CaMgFeMn)SiO Orthorombik

6 35.6 2.51968 Mg2SiO4 Orthorombik 8 42.0 2.14934 11 47.2 1.92396 CaO3 13 50.4 1.80905 Ca4Si6O15(OH)22(Fe(OH)2)

16 62.4 1.48690

Chemical properties of Portland cement are very complex and not fully understood yet. The estimated composition of Portland cement are lime (Ca O), silicate (Si O2), Aluminum (Al2O3) and oxygen iron (Fe2O3). When cement mixing with water, chemical reaction emerge between cement and water. These reactions produce a variety of chemical compounds that cause bonding and hardening, there are four kinds of the most important of C3A (Tricalcium aluminate), C3S (Tricalcium silicate), C2S (Dicalcium silicate) and C4AF (Tetracalcium aluminoflouride) [4]. From

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data which obtained from steel mill PT. ISPAT INDO Surabaya the chemical composition as follows: Ca O = 40 % - 60 % Si O2 = 15 % - 25 % Fe O = 15 % - 25 % Mg O = 8 % - 10 % There are also other ingredients that are less than 1% as Al2O3, Fe3O4 and Fe3O3.

Results of analysis of the peaks in-fractogram concrete before and after irradiated, as follows:

a. Peak fixed and intensity increase is peak no 13 (Ca4Si6O15(OH)2(Fe(OH)2). b. Peak fixed and intensity decrease is peak no 5 and 2 (Ca2Si2O7), no 6 and 4 (MgCO3 or

Ca2SiO4) and 8 (Mg2SiO4) c. Lost Peak no 12 (Al2O3). d. New Peak no 11 (CaO2).

This result shows that the process of γ-ray radiation in the samples resulted in the change of arrangement of atoms in the unit cell. These changes does not create compounds that can damage the concrete because it contains sulfates such as BaSO4, CaSO4, KAl3 (OH)6(SO4)2, CaSO4.2H2O [5].

Scanning Electron Microscope (SEM)

Based on the some photos which produced can not be concluded radiation effect toward on the heavy concrete microstructure. Which can be seen is the interfacial zone between aggregate of heavy concrete with fasta, seen that the zone is more compact. SEM results can be seen in these pictures.

Figure 9 SEM photos of heavy concrete before irradiated

Figure 10 Magnification SEM images of heavy concrete before irradiated

Figure 11 SEM photos of heavy concrete after iirradiated

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Figure 12 Magnification SEM images of heavy concrete after irradiated

CONCLUSION

Based on the results of concrete mix design test according to ASTM C 33, variations in aggregate cement ratio (A / C) 1: 6 cement and water factor (FAS) 0.6 can be summarized as follows:

1. Physical and mechanical properties of steel slag heavy concrete and normal concrete sequence is the unit weight (density) 3272 and 2311 kg/m3; compressive strength: 175,051 and 176,124 kg/cm2; split tensile strength and 120431.26 kg/cm2; modulus of elasticity: 40968.91 and 24202.62 mpa; Poisson's ratio: 0.2995 and 0.24771

2. Nuclar properties The effective attenuation ability of steel slag heavy concrete (density 3272 kg/m3) is

larger than normal concrete (density 2311 kg/m3). As the radiation protection of steel slag heavy concrete 1.5 times greater than normal

concrete. The thicker the wall, the smaller the ratio of the rate of exposure and the effective

attenuation coefficient, for both heavy concrete and normal concrete. 3. X Rays difraction (X-RD)

The results of X-RD analysis of heavy concrete before and after radiated are not the same. This indicated that rays result in changes in the composition of atoms in the unit cell. But do not bring up the properties of compounds that can damage the concrete.

4. SEM Unable to see the effect of radiation on the microstructure of heavy concrete, which can be seen from the SEM test is aggregate interfacial zone with the fasta from the test object.

Recommendation

To complement and follow up the heavy concrete research to radiation is suggested as follows: 1. Need to do further observations on the characteristics of radiation-induced weight concrete. 2. Need to do Attenuation measurements were taken heavy concrete with other energy and

greater activity. 3. Need further research to test the SEM microstructure of concrete.

REFERENCES

1. Mehta, P. Kumar and Monteiro, Paulo J. M. 1993. Concrete, Structure, Properties and Materials, Second Edition, Prentice Hall Inc., New Jersey USA.

2. Abduh, M. 1996. Sifat Proteksi Beton Mutu Tinggi terhadap Radiasi Gamma 0.661 MeV, Tesis S2. Program Pascasarjana ITB. Bandung

3. Dwiatmoko. Yuda. 1998. Studi Beton Berat dengan Agregat Batu Barit Untuk Perisai Radiasi Neutron, Tugas Akhir Jurusan Teknik Sipil Universitas Gadjah Mada, Yogyakarta.

4. Murdock, L. J. dan Brook, K. M., (diterjemahkan oleh Ir. Step-hanus Hendarko). 1986. Bahan dan Praktek Beton, Edisi Keempat, Penerbit Erlangga, Jakarta.

5. Graha, Dody Setia. 1987. Batuan dan Mineral, Nova Bandung.

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Documents

Evaluation of the Characteristic of Heavyweight Concrete .... Appl. Environ. Biol. Sci., 1... · Ristinah S. et al., 2011 Figure 1. The rate of attenuation of thick concrete [3] Steel