STEEL FIBER EFFECT ON THE BEHAVIOR OF HOT MIXTURE ASPHALT WITH VARIABLE ASPHALT CONTENT

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STEEL FIBER EFFECT ON THE BEHAVIOR OF HOT

MIXTURE ASPHALT WITH VARIABLE ASPHALT

CONTENT

Asst. Prof. Dr. Ahmed S. D. AL-Ridha, Asst. Lec. Sinan K. Ibrahim,

Eng.Layth Sahib Dheyab

1,2

Highway and Transportation Department,

Al-Mustansiriya University/ College of Engineering

,

Baghdad, (Iraq

)

3

Consultant Engineer, Baghdad, (Iraq

)

ABRTRACT

The objective of the study is evaluate the effect of added steel fiber as a volume fraction of total volume

mixture (0.1, 0.2 , 0.3 , 0.4) % within surface course grade (type B) according to State Corporation of Roads

and Bridges in Iraq, on behavior of hot asphalt mixture at temperature (60) Co , compaction no. of blows (75)

with different percent of asphalt content (5, 5.5 ,6) % from total weight of mix. The samples were tested by the

mechanical response of reinforced hot asphalt mix with different steel fiber %, in term of stability, flow and bulk

specific gravity. The results in this research found that When the asphalt mixture without steel fiber, the stability

value and bulk specific gravity decreased with increasing asphalt content, and When using steel fiber in hot

asphalt mixture, the stability value and bulk specific gravity of asphalt mixture increasing with increase asphalt

content. This increment increased with increasing volume fraction of steel fiber. And also obtained the optimum

value of volume fraction of steel fiber according to stability value, increased with increasing asphalt content.

Keywords: Asphalt Content, Hot Mix Asphalt, Modifier, Stability, Steel Fiber, Modifier.

I. INTRODUCTION

Asphalt additives have been used to improve pavement performance and decreasemanydistress types ,

which, rutting, thermal cracking and fatigue cracking are the most commondistresses. Fiber is one of the

modifiers used for this objective [1]. Using fibers to enhance theperformance of materials is not a new idea. The

use of fibers to strengthen a hardening material can be foundin Egyptian times when asbestos fiber was used to

support clay pots [2]. Fibers are commonly used as reinforcing agent in concrete, however, the currentmeans of

fiber reinforcement started in the early 1950s [3].

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Flexible pavements are aimed so as to have at minimum20 yearsdesign life. The present studies contain

concentrating on enhance the performance anddesign lifefor off-road pavements. It is achieved that by

usingdifferent modifiersmaterials [4].

Steel fibers have been used in Portland concrete since the first 1900s.The primary fibers shape were

rounded and very smooth and the wire was cut or split to the useful lengths. The use of straight, smooth

fibers has vanished and recent fibers have either roughness, angular ends or are rolled through their length.

Recent commercially existing steel fibers are industrial from drawn steel wire, from cut sheet steel or by the

melt-extraction process which produces fibers that have a crescent-shaped section[5].

II. THE OBJECTIVE OF STUDY

The main objective of the study is evaluate the effect of addedsteel fiber as a volume fraction of total volume

mixture (0.1, 0.2 , 0.3 , 0.4)% within surface course grade (type B) based on State Corporation of Roads and Bridges

of Iraq in on behaviorof hot asphalt mixture withtesting the samples byMarshall test at temperature (60) Co,no.

of compaction blows (75) with different percent of asphalt content (5, 5.5 ,6) % by total weight mix.

III. MATERIALS

In This study,used local materialthat be used in road erection in Iraq except the material of steel fibers,are

available in local market in Baghdad but not yet used in the asphalt road constructions.

3.1Bitumen

Thebitumenthat used in study manufacture in Daurah refinery with grade (40-50) .The physical characteristics

of bitumen are illustrated in Table (1).

Table (1) Physical Characteristicsof Bitumen

Property

ASTM[6]

Designation

Number

Bitumen

Penetration (25C, 100 Gm, 5sec), (1/10 mm) D-5 43

Softening Point (Ring And Ball), C D-36 51.5

Ductility, Cm D-113 101

Flash Point (Cleaveland Open-Cup) D-92 335

Specific Gravity , 25 C D-70 1.048

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3.2 Aggregate

The source of mineral aggregate is from local quarry (Al-Nibai). The gradation of surface course with

nominalsize of (9.5mm) was used consider with State Corporation of Roads and Bridges[7].The Table(2) and

Fig.(1) show the upper and lower limits of the Iraqi standards and the selected gradation of mineral aggregate.

Table (2)Selectedand Standard Limits Gradations of Mineral Aggregate[7]

Sieve No. Sieve Opening (mm)

Surface Course Gradation (Type B)

StandardGradation Limits Selected Gradation

½ 12.5 100 100

3/8 9.5 90-100 95

4 4.75 55-85 70

8 2.36 32-67 50

50 0.4 7-23 15

200 0.075 4-10 7

Figure (1): selected and standard limits gradation of mineral aggregate

3.3 Mineral Filler

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Table (3): Chemical Conformation of Portland Cement.*

Chemical Composition* (%) Cement

L.O.I. 3.5

SiO2 20.25

CaO 62.44

MgO 2.19

SO3 1.88

Fe2O3 4.32

Al2O3 4.73

Table (4): Physical Characteristicsof Portland cement*

Property Cement

Specific Surface* (cm2/gm) 3372

Bulk sp. gr. (gm/cm3) 3.4

% Passing No. 200 96

* The Result fromthe National Center for Construction Laboratories.

3.4 Steel Fiber

The steel fibers that used in this research were industrial by Bekaert Corporation. Steel fiber has a widthand

length of about 175 μm, 13 mm respectively [8]. The steel fibers characteristicsillustrated in Table (5). A thin

brass coating is applied to the fibers through the drawing process; therefore, the new fibers may be gold/-color.

Fig. (2) illustrations the steel fibers used in this study.

Table (5): Characteristics of the Steel Fibers*

Description Length (mm) Diameter (mm) Density (Kg/m3)

Tensile Strength

Fu(Mpa) Aspect Ratio

Straight 13 0.2 7800 2600 65

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Figure (2) steel fiber

IV. WORK STUDY

The work plan of this study is toprepare an asphalt samples from selected grade of mineral aggregate , mineral

filler and differentpercent of steel fiber (0 ,0.1 ,0.2 ,0.3 ,0.4) % of total mixturevolume and asphalt content

(5.0,5.5 ,6.0)% of total mixtureweight, and the asphalt applied to several cycles of heating. The samples were

testedto computeMarshall stabilityandflow, bulk specific gravity at temperature(60 Co) and compaction

blows(75). Fig. (3)represent the work plan of study.

Fiber

0%

0.1%

0.2%

0.3%

Fiber

0%

0.1%

0.2%

0.3%

Fiber

0%

0.1%

0.2%

0.3%

Ac 40-50, selected

aggregate grade

Compaction

75 blows

Temperature

60 C

o

Asphalt Content

6 %

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V. EXPERIMENTAL RESULTS

The following tests were achievedin asphalt laboratory on the prepared samples to assessment the performance

ofHMA with different quantities of steel fiber:

1. Marshal Method (Stability and flow values, ASTM D 1559).

2. Bulk specific gravity test (ASTM D 2726).

5.1 Marshal Method (Stability and flow values)

Marshall Method for mix design is used in this research as ameasure to plastic flow. Stability and flow were

tested for allspecimens using ASTM D 1559.

5.1.1. Effect of Volume Fraction of Steel Fiber on Stability with Variable Asphalt Content

Fig.(4) show the effect of increasing steel fiber on stability value of marshal test, with three variable asphalt

content (5, 5.5, and 6)%. This figure represents the optimum point of volume fraction of steel fiber according to

stability value, increased with increasing asphalt content. This phenomenon caused may be that when increasing

the volume fraction of steel fiber, the surface area was increased which lead to required more asphalt content

that covered this area, that mean the increasing in steel fiber increase the required optimum asphalt content for

the mixture and improve the activity of steel fiber.

When add steel fiber the stability value was increased with variable asphalt content, this behavior may be that

the steel fiber prevent the created of micro-cracks and reduce growth of cracks[9].

0.0 0.1 0.2 0.3 0.4 0.5

Fiber content by volume (Vf)%

4 6 8 10 12 14 16 18 20

S

ta

b

il

it

y

(

k

N

)

0.0 0.1 0.2 0.3 0.4 0.5

Fiber content by volum e (Vf)%

0.0 0.1 0.2 0.3 0.4 0.5

Fiber content by volume (Vf)%

Asphalt content = 5.0% Asphalt content = 5.5% Asphalt content = 6.0%

Figure (4) effect of volume fraction steel fiber on stability with variable asphalt content

5.1.2. Effect of Asphalt Content on Stability with Variable Volume Fraction of Steel Fiber

The effect of increasing asphalt content (5,5.5,6) % on stability value with variable steel fiber (0,0.1, 0.2,0.3,

0.4) % illustrated in fig. (5). The figure represent thatwhen the asphalt mixture without steel fiber, the stability

value decreases with increasing asphalt content. And when adding steel fiber , the stability value increased with

increasing asphalt content at the same volume fraction of steel fiber, and this increasement increase with

increasing volume fractin of steel fiber. This phonomena that may be when increasing steel fiber the surface

area was increased which requierd to incresead the asphalt content to fill the voids and increase the adhesion in

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4.5 5.0 5.5 6.0 6.5

Asphalt content by weight %

4 6 8 10 12 14 16 18 20 S ta b il it y ( k N )

4.5 5.0 5.5 6.0 6.5

A sphalt content by w eight %

(Vf )=0.3 % (Vf )=0.4%

4.5 5.0 5.5 6.0 6.5

4 6 8 10 12 14 16 18 20 S ta b il it y ( k N )

4.5 5.0 5.5 6.0 6.5

(Vf )=0.0 % (Vf )=0.1% _{(Vf )=0.2%}

Figure (5) effect of asphalt content on stability with variable volume fraction of steel fiber

5.1.3. Flow Value Relationship with Variable Volume Fraction of Steel Fiber and Asphalt Content

The flow value of Marshall test with volume fraction steel fiber (0,0.1, 0.2,0.3, 0.4) % and asphalt

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4.5 5.0 5.5 6.0 6.5

2.10 2.13 2.16 2.19 2.22 2.25 2.28 2.31 2.34 2.37 2.40 D en si ty ( g m /c m 3 )

4.5 5.0 5.5 6.0 6.5

A sphalt content by w eight %

(Vf)=0.3% (Vf)=0.4%

5.2. Bulk Specific Gravity Relationship with Variable Rate of Steel Fiber and Asphalt Content

This test was achieved in laboratory using bulk specific gravity device Fig. (7), the Bulk Specific Gravity

Relationship with volume fraction of Steel Fiber (0, 0.1, 0.2, 0.3, 0.4) % and Asphalt Content (5, 5.5, 6)

%shown in fig. (8). The figure illustrated that when the asphalt mixture without steel fiber, the bulk specific

gravity value decreases with increasing asphalt content. And when adding steel fiber, the bulk specific gravity

value increased with increasing asphalt content at the same volume fraction of steel fiber, and this increasement

increase with increasing volume fractin of steel fiber.

Figure (7) bulk specific gravity device

4.5 5.0 5.5 6.0 6.5

2.10 2.13 2.16 2.19 2.22 2.25 2.28 2.31 2.34 2.37 2.40 D en si ty ( g m /c m 3 )

4.5 5.0 5.5 6.0 6.5

Asphalt content by w eight %

4.5 5.0 5.5 6.0 6.5

(Vf)=0.0% (Vf)=0.1% _(Vf)=0.2%

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VI. CONCLUSION

1- The optimum value of volume fraction of steel fiber according to stability result, increased with increasing

asphalt content.

2- The effect of asphalt content on stability value with variable volume fraction of steel fiber lead to:

a- When the asphalt mixture without steel fiber, the stability value decrease with increasing asphalt content.

b- Whenadding steel fiber to asphalt mix, the stability value increased with increasing asphalt content at the

same volume fraction of steel fiber, and this increasement increase with increasing volume fractin of steel

fiber.

3- The effect ofAsphalt Contentwith Variable volume fraction of Steel Fiber on Bulk Specific lead to:

a- When the asphalt mixture without steel fiber, the bulk specific gravity decrease with increasing asphalt

content.

b- When using steel fiber in hot asphalt mixture, the bulk specific gravity of asphalt mixture increasing with

increase asphalt content. This increment increased with increasing volume fraction of steel fiber.

VII. ACKNOWLEDGMENT

We thank the colleagues listed below for their achievement search:

1.

Dr. Zainab Alkaisi . Assistant professor at Highway and Transportation Department – College of

Engineering – Al- Mustansiriya University – Baghdad – Iraq.

2.

Dr.Mohammad B. Abduljabar.Lecturer at Highway and Transportation Department – College of Engineering

– Al- Mustansiriya University – Baghdad – Iraq.

3.

Lecture Atheer N. Hameed ,Lecturer. Abbas F. Jassim [PhD student in USA] , Dr. Nagham T. H. Al-Shafi'i

.Staff members of Highway and Transportation Department – College of Engineering – Al- Mustansiriya

University – Baghdad – Iraq.

4.

Staff members of asphalt laboratory of Highway and Transportation Department – College of Engineering –

Al- Mustansiriya University – Baghdad – Iraq, essentially engineer Ahmed Sh. Qusad and Assist

engineerTeba T. Khaleed.

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[2] Mehta, P.K. and Monteiro, P.J.M., 2006.Concrete; Microstructure, Properties, and Materials. 3rd ed., New

York: McGraw-Hill.

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[5] Ravindra V. S., C. B. Mishra., F. S. Umrigar and D. A. Sinha., 2011. Use of Steel Fiber in Concrete

Pavement: A Review. National Conference on Recent Trends in Engineering & Technology.

[6] ASTM Annual Book of ASTM Standard.,1996.Section 4, Volume 04.03, Road and Paving Materials;

Pavement Management Technology.American Society for Testing and Materials, Philadelphia, Pa.

[7] SCRB ., 2003. General Specification for Roads and Bridges.Section R9, Hot –Mix Asphalt Concrete

Pavement, Revised Edition.

[8] Roux, N., Anreade, C and Sanjuan, M. A.,1996. Experimental Study of Durability of Reactive Powder

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[9] Dr. Ahmed S.D. AL- Ridha, Mr. AtheerNaji Hameed, Mr.SinanKhaleel Ibrahim, "Effect of steel Fiber on

thePerformance of Hot Mix Asphalt with DifferentTemperatures and Compaction". Australian Journal of