Improving impact and mechanical properties of gap graded concrete

14
International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308 (Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME 118 IMPROVING IMPACT AND MECHANICAL PROPERTIES OF GAP- GRADED CONCRETE BY ADDING WASTE PLASTIC FIBERS Dr. Abdulkader Ismail Abdulwahab Al-Hadithi Assist. Prof. -College of Eng. / University of Anbar /Ramadi, Al-Anbar, Iraq. ABSTRACT This research includes the study of the effect of adding the chips resulting from cutting the plastic beverage bottles by hand (which is used in Iraqi markets now) as small fibers added to the gap-graded concrete. These fibres were added with different percentages of concrete volumes. These percentages were (0.5%) , (1%) and (1.5%). Reference concrete mix was also made for comparative reasons. Results proved that adding of waste plastic fibres with these percentages leads to improvements in compressive strength and Splitting Tensile Strength of concretes containing plastic fibres, but the improvement in Splitting Tensile Strength appeared more clearly. There is significant improvement in low-velocity impact resistance of all waste plastic fibres reinforced concrete (WPFRC) mixes over reference mix. Results illustrated that waste plastic fibres reinforced mix of (1.5%) give the higher impact resistance than others, the increase of its impact resistance at failure over reference mix was (328.6%) while, for waste plastic fibres reinforced mix of (0.5%) was (128.6%) and it was (200%) for fiber reinforced mix of (1%). Some photos were taken to the microstructures of concrete by using Scanning Electronic Microscope (SEM) and Optical Microscope. Keywords: Fiber Reinforced Concrete, Waste Plastic Fiber, Impact, Mechanical Properties, Gap-graded Concrete. 1. INTRODUCTION Since ancient times, fibers have been used to reinforce brittle materials. Straw was used to reinforce sun-baked bricks, and horsehair was used to reinforce masonry mortar and plaster. A pueblo house built around 1540, believed to be the oldest house in the U.S., is INTERNATIONAL JOURNAL OF CIVIL ENGINEERING AND TECHNOLOGY (IJCIET) ISSN 0976 – 6308 (Print) ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), pp. 118-131 © IAEME: www.iaeme.com/ijciet.asp Journal Impact Factor (2013): 5.3277 (Calculated by GISI) www.jifactor.com IJCIET © IAEME
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Transcript of Improving impact and mechanical properties of gap graded concrete

Page 1: Improving impact and mechanical properties of gap graded concrete

International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308

(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME

118

IMPROVING IMPACT AND MECHANICAL PROPERTIES OF GAP-

GRADED CONCRETE BY ADDING WASTE PLASTIC FIBERS

Dr. Abdulkader Ismail Abdulwahab Al-Hadithi

Assist. Prof. -College of Eng. / University of Anbar /Ramadi, Al-Anbar, Iraq.

ABSTRACT

This research includes the study of the effect of adding the chips resulting from

cutting the plastic beverage bottles by hand (which is used in Iraqi markets now) as small

fibers added to the gap-graded concrete. These fibres were added with different percentages

of concrete volumes. These percentages were (0.5%) , (1%) and (1.5%). Reference concrete

mix was also made for comparative reasons.

Results proved that adding of waste plastic fibres with these percentages leads to

improvements in compressive strength and Splitting Tensile Strength of concretes containing

plastic fibres, but the improvement in Splitting Tensile Strength appeared more clearly.

There is significant improvement in low-velocity impact resistance of all waste

plastic fibres reinforced concrete (WPFRC) mixes over reference mix. Results illustrated that

waste plastic fibres reinforced mix of (1.5%) give the higher impact resistance than others,

the increase of its impact resistance at failure over reference mix was (328.6%) while, for

waste plastic fibres reinforced mix of (0.5%) was (128.6%) and it was (200%) for fiber

reinforced mix of (1%).

Some photos were taken to the microstructures of concrete by using Scanning

Electronic Microscope (SEM) and Optical Microscope.

Keywords: Fiber Reinforced Concrete, Waste Plastic Fiber, Impact, Mechanical Properties,

Gap-graded Concrete.

1. INTRODUCTION

Since ancient times, fibers have been used to reinforce brittle materials. Straw was

used to reinforce sun-baked bricks, and horsehair was used to reinforce masonry mortar and

plaster. A pueblo house built around 1540, believed to be the oldest house in the U.S., is

INTERNATIONAL JOURNAL OF CIVIL ENGINEERING AND

TECHNOLOGY (IJCIET)

ISSN 0976 – 6308 (Print)

ISSN 0976 – 6316(Online)

Volume 4, Issue 2, March - April (2013), pp. 118-131 © IAEME: www.iaeme.com/ijciet.asp

Journal Impact Factor (2013): 5.3277 (Calculated by GISI) www.jifactor.com

IJCIET

© IAEME

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International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308

(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME

119

constructed of sun-baked adobe reinforced with straw. In more recent times, large scale

commercial use of asbestos fibers in a cement paste matrix began with the invention of

the Hatschek process in 1898. Asbestos cement construction products are widely used

throughout the world today. However, primarily due to health hazards associated with

asbestos fibers, alternate fiber types were introduced throughout the 1960s and 1970s (1).

2. FIBER REINFORCED CONCRETE

Concrete is considered a brittle material as it has low tensile strength and failure

strain. It is difficult to suppress the formation and growth of cracks developed therein and

is apt to be fractured by tensile load or dynamic load. To resolve these drawbacks and to

prolong the service duration of concrete, fiber-reinforced concrete has been developed in

which fibers are incorporated to improve the mechanical properties (2).

Fiber-reinforced concrete, or fiber concrete, is a composite. It takes the advantages of the

high compressive strength of concrete and the high tensile strength of fibers. Furthermore,

it increases the energy absorption capacity of concrete through the adhesion peeling off,

pulling out, bridging, and load transmitting of fibers in the concrete, and improves the

ductility, toughness, and impact strength(2).

The strength potential of nylon-fiber-reinforced concrete was investigated versus

that of the polypropylene-fiber-reinforced concrete by Song et al(3). The compressive and

splitting tensile strengths and modulus of rupture (MOR) of the nylon fiber concrete

improved by 6.3%, 6.7%, and 4.3%, respectively, over those of the polypropylene fiber

concrete. On the impact resistance, the first-crack and failure strengths and the percentage

increase in the post first-crack blows improved more for the nylon fiber concrete than for

its polypropylene counterpart.

Poly(vinyl butyral) (PVB) which has many special engineering aggregate

properties is utilized as the sole aggregate in a research done by Xu et al(4) to develop a

novel cementitious composite reinforced with Poly (vinyl alcohol) (PVA) fiber . Impact

energy absorption capacity is evaluated based on the Charpy impact test. The results show

that PVB composite material has lower density but higher impact energy absorption

capability compared with conventional lightweight concrete and regular concrete. The

addition of PVA fiber improves the impact resistance with fiber volume fractions. A

model based on fiber bridging mechanics and the rule of mixtures is developed to

characterize the impact energy. A good correlation was obtained for the materials tested

when experimental results are compared to those predicted by the developed model.

Experimental investigations were conducted by Song et al(5) on tyre fiber

specimens with different variables such as length, diameter of holes and percentage of

coarse aggregate replacement by tyre fibers. Impact resistance test was done by ACI

standard and acid and water absorptions tests were conducted by Indian standard. Results

obtained from the tests are use to determine the optimum size of the tyre fiber specimen

that could be used in the rubberized concrete mixture to give the optimum performance.

The rubberized concrete with tyre fiber specimen L50-D5 10% has shown good transport

characteristics and impact resistance.

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International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308

(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME

120

3. WASTE PLASTIC FIBER REINFORCED CONCRETE

Alhozaimy(6) study the effects of using recycled fibers (RP) from industrial or post

consumer recycled plastic waste as reinforcing fibers in concrete. The mechanical properties,

plastic shrinkage cracking and permeability of RP fibrous concrete were investigated. Four

different volume fractions (1, 2, 3 and 4%) of recycled plastic low density polyethylene fibers

(RP fibers) and control with no RP fibers were considered.

The results showed that at volume fraction of 1 to 2% of RP fibers, plastic shrinkage cracking

was almost similar to plain concrete without RP fibers (i.e., 0%) while at a volume fraction of

3 to 4 %, no plastic shrinkage cracks were observed. Also, it was found that RP fibers have

no significant effect on the compressive and flexural strengths of plain concrete at volume

fractions used in this study. However, the RP fibers increased flexural toughness up to 270%.

Yadav(7) investigates the change in mechanical properties of concrete with the

addition of plastics in concrete. Along with the mechanical properties, thermal characteristics

of the resultant concrete is also studied .This research found that the use of plastic aggregates

results in the formation of lightweight concrete. The compressive, as well as tensile strength

of concrete reduces with the introduction of plastics. The most important change brought

about by the use of plastics is that the thermal conductivity of concrete is reduced by using

plastics in concrete.

Thirty kilograms of waste plastic of fabriform shapes was used by Ismail (8) et al as a

partial replacement for sand by 0%, 10%, 15%, and 20% with 800 kg of concrete mixtures.

All of the concrete mixtures were tested at room temperature. These tests include performing

slump, fresh density, dry density, compressive strength, flexural strength, and toughness

indices. Seventy cubes were molded for compressive strength and dry density tests, and 54

prisms were cast for flexural strength and toughness indices tests. Curing ages of 3, 7, 14, and

28 days for the concrete mixtures were applied in this work. The results proved the arrest of

the propagation of micro cracks by introducing waste plastic of fabriform shapes to concrete

mixtures. This study insures that reusing waste plastic as a sand-substitution aggregate in

concrete gives a good approach to reduce the cost of materials and solve some of the solid

waste problems posed by plastics.

3. EXPERIMENTAL PROGRAM

3.1. Materials

3.1.1. Cement Ordinary Portland Cement (OPC) ASTM Type I is used. The cement is complied to

Iraqi specification no.5/ 1999(9)

3.1.2. Fine Aggregate Natural gap-graded sand is used in production of concrete specimens which was

used in this study. Results of sieve analysis of this sand are shown in Table (1).

3.1.3. Coarse Aggregate Gap-graded uncrushed course aggregate is used for all concrete mixes in this

study. Table (2) gives the sieve analysis results of that course aggregate.

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International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308

(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME

121

Table (1): Sieve Analysis Results of the Sand Used.

Percent Passing

Sieve Size (mm) No Limits of British Standard

Specifications (BSS. 882 (Zone 1))(10) Fine aggregate

90-100 100 4.75mm 1

60-95 46.6 2.36mm 2

30-70 4.6 1.18mm 3

15-34 0.28 600micron 4

5-20 0 300micron 5

0-10 0 150micron 6

Fig.1: Grading of fine aggregate used in this study.

Table (2): Sieve Analysis Results of the Gravel Used.

90

60

30

15

50

10095

70

34

20

10

100

46.6

4.60.28 0 00

20

40

60

80

100

120

Pe

rce

nta

ge

Pa

ssin

g %

Seive Size (mm)

Lower Passing

Percentage

Upper Passing

Percentage

Actual Fine Agg.

Grading

Percent Passing

Sieve Size (mm) No Limits of British Standard Specifications

(BSS. 882 (Zone 1))(10) Coarse aggregate

95-100 100 37.5 1

30-70 80 20 2

10-35 18.8 10.0 3

0-5 1.2 5.0 4

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International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308

(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME

122

Fig.2: Grading of coarse aggregate used in this study.

3.1.4 Mixing Water

Ordinary tap water is used in this work for all concrete mixes and curing of

specimens.

3.1.5. Plastic Fiber Plastic fibers with average 1cm length and average 2mm width were produced by

cutting plastic beverage bottles by hand.

3.2. Preparation of Specimens and Curing. The moulds were lightly coated with mineral oil before use, according to ASTM

C192-88(11), concrete casting was carried out in three layers. Each layer was compacted by

using a vibrating table until no air bubbles emerged from the surface of concrete and the

concrete is levelled off smoothly to the top of moulds.

3.3 Mixing and Compaction of Concrete Mixing operations were made in the concrete laboratory in the civil engineering

department of University of. A 0.1m3

pan mixer was used. Pouring the coarse aggregates

made mixing and cement in two alternate times and mixing them dry while adding the fibers

until a homogenous dry mix is obtained. The water is added then and mixing continued until

final mixing mix is obtained.

The concrete mix is poured, in three layers, in the molds. An electrical vibrator made

compaction for not more than 10 sec.

95

30

10

0

100

70

35

5

100

80

18.8

1.20

20

40

60

80

100

120

37.5mm 20mm 10mm 5mm

Pe

rce

nta

ge

Pa

ssin

g %

Seive Size (mm)

Lower Passing

Percentage

Upper Passing

Percentage

Actual Coarse

Aggregate Grading

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International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308

(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME

123

3.4. Mixes

Table (3): Mix Proportions of Materials Used in this Work for Making One Cubic Meter of

Concrete.

Symbol Cement

(kg)

Sand

(kg)

Gravel

(kg)

Water

Liter

Waste Plastic Fibers

Waste

Plastic

Fibers(kg)

Waste

Plastic

Fibers%

RC 412.5 618.7 1237 185.6 0 0

F0.5 410.4 615.6 1231.2 184.7 5.5 0.5%

F1.0 408.4 612.6 1225.12 183.8 11 1%

F1.5 406.3 609 1218.94 182.8 16.5 1.5%

3.5. Tests

3.5.1. Compressive Strength Test The compressive strength of concrete is one of the fundamental properties used to

specify the quality of concrete. The digital hydraulic testing machine (ELE) with capacity of

(2000) KN and rate of 3 KN/Sec, is used for the determination of compressive strength of

concrete. Three cubes of (100×100×100) mm concrete were tested according to B.S.1881.

Part(5):1989(12). The average of three cubs was recorded for each testing age (7, 28 and 56)

days respectively for compressive strength.

3.5.2. Spletting Tensile Strength Splitting tensile strength was conducted on cylinders of (100mm diameter and 200mm

height according to ASTM C496-05 (13). The average of three specimens in each case was

taken. The splitting tensile strength was determined by using the digital hydraulic testing

machine (ELE) with capacity of (2000) KN and rate of (0.94) KN/Sec. The average of three

cylinders was recorded for each testing age (7, 28 and 56) days respectively for splitting

tensile strength.

3.5.3. Low Velocity Impact Test

Eight 56-day age (500 × 500 × 50) mm slab specimens were tested under low

velocity impact load. The impact was conducted using 1400gm steel ball dropping freely

from height equal to 2.4m. The test rig used for low velocity impact test consists of three

main components: Plate (1).

A steel frame, strong and heavy enough to hold rigidly during impact loading. The

dimensions of the testing frame were designed to allow observing the specimens (square slab)

from the bottom surface to show developing failure, during testing. The specimen was placed

accurately on mold which were welded to the support ensure the simply supported boundary

condition.

The vertical guide for the falling mass used to ensure mid-span impact. This was a

tube of a round section.

-Steel ball with a mass of 1400 gm.

-Specimens were placed in their position in the testing frame with the finished face

up. The falling mass was then dropped repeatedly and the number of blows required to cause

first crack was recorded. The number of blows required for failure (no rebound) was also

recorded.

Page 7: Improving impact and mechanical properties of gap graded concrete

International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976

(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March

Plate (1): Test Rig Used for Low Velocity Impact Test

4-RESULTS AND DISCUSSION

4.1. Compressive Strength Figs. (3) and (4) show the variation the compressive strength with waste plastic fiber

percentages for all ages. From these figures it can be seen that, the compressive strength of all

specimens increases with time, but the percentage of increasing in compressive strength differs

between the reference concrete RC and the fiber reinforced concrete FRC. Table (4) show the

results of compressive strength of all mixes in this research.

All the mixes have shown strength val

mixes with waste plastic fibers percentage by volume (V

compressive strength more than that of reference mix at 56 age of test. The maximum value of

increment was equal to (7.5%) for concrete mix containing (1%) waste plastic fiber. The

compressive strength of mix with (V

and 56 day ages. The reason of this is the fiber after which (1%) had formed bulks and segregat

on mix. This led to form stiff bond about these bulks.

Table (4): Compressive Strength of FRCs at Different Ages with

Mix Waste plastic fibers

Vf %

RC 0

FR0.5 0.5

FR1.0 1

FR1.5 1.5

Journal of Civil Engineering and Technology (IJCIET), ISSN 0976

6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME

124

Test Rig Used for Low Velocity Impact Test

Figs. (3) and (4) show the variation the compressive strength with waste plastic fiber

percentages for all ages. From these figures it can be seen that, the compressive strength of all

ut the percentage of increasing in compressive strength differs

between the reference concrete RC and the fiber reinforced concrete FRC. Table (4) show the

results of compressive strength of all mixes in this research.

All the mixes have shown strength values above (35) MPa at 56 day age. Fiber reinforced

mixes with waste plastic fibers percentage by volume (Vf%) equal to (0.5%) and (1%) have a

compressive strength more than that of reference mix at 56 age of test. The maximum value of

o (7.5%) for concrete mix containing (1%) waste plastic fiber. The

compressive strength of mix with (Vf=1.5%) decrease if comparing with reference mix at 28 day

The reason of this is the fiber after which (1%) had formed bulks and segregat

on mix. This led to form stiff bond about these bulks.

Compressive Strength of FRCs at Different Ages with

Waste plastic fibers Compressive strength (MPa) at indicated ages in

(day)

7 28

26.4 33

23.4 32

27.3 34

26 29

Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308

April (2013), © IAEME

Figs. (3) and (4) show the variation the compressive strength with waste plastic fiber

percentages for all ages. From these figures it can be seen that, the compressive strength of all

ut the percentage of increasing in compressive strength differs

between the reference concrete RC and the fiber reinforced concrete FRC. Table (4) show the

ues above (35) MPa at 56 day age. Fiber reinforced

%) equal to (0.5%) and (1%) have a

compressive strength more than that of reference mix at 56 age of test. The maximum value of

o (7.5%) for concrete mix containing (1%) waste plastic fiber. The

=1.5%) decrease if comparing with reference mix at 28 day

The reason of this is the fiber after which (1%) had formed bulks and segregate

Compressive strength (MPa) at indicated ages in

56

41.2

41.3

44.3

35

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International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976

(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March

Fig. 3: The relationship between compressive strength and age for all mixes.

Fig.4: Development of Compressive Strengths for all Concrete Mixes at All Ages.

4.2. Splitting Tensile Strength The results of splitting tensile strength for various types of concrete specimens at age

(7, 14, 56) days. The relationship between splitting tensile strength and various ratios of

waste plastic fiber is shown in figures (5) and (6). It can be seen that the addition

plastic fibers leads to increase of remarkable splitting tensile strength but it decreases after

(Vf=1% ) of waste plastic fiber ,but it is still higher than the splitting of reference concrete. The

increase is due to the fact that the presence of

Also we can note that the plain concrete cylinders fail suddenly and split into two separate

parts, while the mode of failure in cylinders with waste plastic fibers is cracked at failure

without separation. The maximum splitting tensile strength is obtained at mixing containing

(1%) waste plastic fiber by volume.

85

23

28

33

38

43

20

25

30

35

40

45

Co

mp

res

siv

e S

tren

gth

(M

Pa

)

35

Age (Day)

Journal of Civil Engineering and Technology (IJCIET), ISSN 0976

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125

The relationship between compressive strength and age for all mixes.

Development of Compressive Strengths for all Concrete Mixes at All Ages.

of splitting tensile strength for various types of concrete specimens at age

(7, 14, 56) days. The relationship between splitting tensile strength and various ratios of

waste plastic fiber is shown in figures (5) and (6). It can be seen that the addition

plastic fibers leads to increase of remarkable splitting tensile strength but it decreases after

) of waste plastic fiber ,but it is still higher than the splitting of reference concrete. The

increase is due to the fact that the presence of waste plastic fibers arrests cracks progression.

Also we can note that the plain concrete cylinders fail suddenly and split into two separate

parts, while the mode of failure in cylinders with waste plastic fibers is cracked at failure

The maximum splitting tensile strength is obtained at mixing containing

(1%) waste plastic fiber by volume.

13 18 23 28 33 38 43 48 53 5810 15 20 25 30 35 40 45 50 55 60

Age (Day)

Vf% of waste plastic fibers

0%

Vf=0.5%

Vf=1%

Vf=1.5%

0%0.5%

1%1.5%

0

20

40

60

26.4

33

41.2

23.4

32

41.3

27.3

34

44.3

26

29

Vf% of waste plastic fibers

Co

mp

ress

ive

Str

en

gth

(M

pa

)0%

0.5%

1%

1.5%

Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308

April (2013), © IAEME

The relationship between compressive strength and age for all mixes.

Development of Compressive Strengths for all Concrete Mixes at All Ages.

of splitting tensile strength for various types of concrete specimens at age

(7, 14, 56) days. The relationship between splitting tensile strength and various ratios of

waste plastic fiber is shown in figures (5) and (6). It can be seen that the addition of waste

plastic fibers leads to increase of remarkable splitting tensile strength but it decreases after

) of waste plastic fiber ,but it is still higher than the splitting of reference concrete. The

waste plastic fibers arrests cracks progression.

Also we can note that the plain concrete cylinders fail suddenly and split into two separate

parts, while the mode of failure in cylinders with waste plastic fibers is cracked at failure

The maximum splitting tensile strength is obtained at mixing containing

0.5%

1.5%

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International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976

(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March

Table (5): Splitting Tensile Strength of FRCs at Different Ages

Mix Waste plastic fibers

Vf %

RC 0

FR0.5 0.5

FR1.0 1

FR1.5 1.5

Fig.5: The relationship between splitting tensile strength and age for all mixes.

Fig.6: Development of Seplitting

85 10

0.90

1.10

1.30

1.50

1.70

0.80

1.00

1.20

1.40

1.60

1.80

Splittin

g T

ensile S

trength

(M

Pa)

56

Age (Day)

Journal of Civil Engineering and Technology (IJCIET), ISSN 0976

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Splitting Tensile Strength of FRCs at Different Ages

Waste plastic fibers Compressive strength (MPa) at indicated ages in

(day)

7 28

0.88 1

0.884 1.04

1.138 1.57

1 1.38

The relationship between splitting tensile strength and age for all mixes.

of Seplitting Tensile Strengths for all Concrete Mixes at All Ages.

13 18 23 28 33 38 43 48 53 580 15 20 25 30 35 40 45 50 55 60

Age (Day)

Vf% of waste plastic fibers

0%

Vf=0.5%

Vf=1%

Vf=1.5%

0%0.5%

1%1.5%

0

0.5

1

1.5

2

7

0.88

1

1.44

0.884

1.04

1.6

1.132

1.57

1.7

1

1.13

1.38

Vf% of waste plastic fibers

Sp

litt

ing

Te

nsi

le S

tre

ng

th (

Mp

a)

0%

0.5%

1%

1.5%

Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308

April (2013), © IAEME

Compressive strength (MPa) at indicated ages in

56

1.44

1.6

1.7

1.38

The relationship between splitting tensile strength and age for all mixes.

all Concrete Mixes at All Ages.

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(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME

127

4.3. Impact Resistance and Mode of Failure

The impact resistance of concrete slabs was determined in terms of the number of

blows required to cause complete failure of the slabs. The mass of (1400 gm) was repeatedly

dropped for a (2400 mm) height up to the failure of slabs. Two sets of number of blows were

recorded depending on the mode of failure: at first crack and at failure. Total fracture energy

here is the product of the height of the drop (2.4 m) and weight of the dropped mass (1.4 kg)

by the number of blows to failure. The results of low velocity impact tests of all mixes at

age of (56) days are presented in Table (4) below, it can be seen that there is a significant

improvement in the low-velocity impact resistance for the all mixes containing waste plastic

over reference mix. Fig.(7) shows the effect of adding waste plastic which were added as a

percentage by volume of the concrete at first crack and failure. It can be seen that, when the

ratio of waste plastic: concrete percentage increased the impact resistance also increased. For

a (1.5%) ratio the number of blows reached to (30) blows at failure while they recorded as

(16) at first crack (each result average for two specimens). The increase of its impact

resistance at failure over reference mix was (328.6%). Fig.(8) showed the relationship

between impact resistance and splitting tensile strength at failure.

From figures (7), (8) and (9) it can be noticed that, at percentage of (1.5%) of waste

fiber add to concrete, the specimens show a good resistance to fracture due to the distribution

of fiber across the concrete. That means the increase in tension stress, ductility, more energy

absorption and bond strength.

Some photos were be taken to the microstructure of WPFRC by optical microscope in

the laboratories of Iraqi Ministry of Sciences and Technology and other photos were be taken

by Scanning Electronic Microscope Technology (SEM) in the labs of South West Jiaotong

University-China. Plate (2) and Plate (3) show the waste plastic fiber inside the

microstructure of concrete.

Table (4): Results of impact test at 56 days age

Panels Vf %

No. of blows to first

crack

No. of blows to

failure Total energy (Nm)

Results Mean Results Mean First

crack Failure

RC

0

6 5

8 7 164.8 230.72

4 6

FR0.5

0.5

9 9

17 16 296.64 527.36

9 15

FR1.0 1 14

13 18

21 428.48 692.16 12 24

FR1.5 1.5 15

16 33

30 527.36 988.8 17 27

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Fig. 7: The relationship between impact resistance (number of blows) and fiber content by

volume for all mixes.

Fig. 8: The relationship between splitting tensile strength and impact resistance (number of

blows) and for all mixes.

0.3 0.8 1.30.0 0.5 1.0 1.5

(Vf%) of Wast Plastic Fibers

5

15

25

0

10

20

30

Imp

ac

t R

es

ista

nc

e (

No

. o

f B

low

s)

Impact Resistance

First Crack

Final Failure

8 13 18 23 285 10 15 20 25 30

Impact Resistance (No. of Blows Until Failure)

1.3

1.5

1.7

1.2

1.4

1.6

1.8

Sp

litt

ing

Te

nsil

e S

trn

gth

(M

Pa)

Polynomial

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International Journal of Civil Engineering and Technology (IJCIET), ISSN 0976

(Print), ISSN 0976 – 6316(Online) Volume 4, Issue 2, March

Fig. 9: The relationship between total energy and waste plastic fiber content by volume for

a

Plate(2):a-50X photo of WPFRC

b-200X photo of WPFRC microstructure by optical microscope.

First crack

Failure

Journal of Civil Engineering and Technology (IJCIET), ISSN 0976

6316(Online) Volume 4, Issue 2, March - April (2013), © IAEME

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The relationship between total energy and waste plastic fiber content by volume for

all mixes.

b

50X photo of WPFRC microstructure by optical microscope.

200X photo of WPFRC microstructure by optical microscope.

0%0.5%

1%1.5%

0

200

400

600

800

1000

First crack

Failure

164.8

230.72296.64

527.36

428.48

692.16

527.36

988.8

Vf%

Journal of Civil Engineering and Technology (IJCIET), ISSN 0976 – 6308

April (2013), © IAEME

The relationship between total energy and waste plastic fiber content by volume for

microstructure by optical microscope.

200X photo of WPFRC microstructure by optical microscope.

400

600

800

1000

To

tal

En

erg

y (

Nm

)

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130

a

b

c

Plate(3):a-150X photo of WPFRC microstructure by SEM.

b-150X photo of WPFRC microstructure by SEM.

c-200X photo of WPFRC microstructure by SEM.

5. CONCLUSION

Based on the expiremental work and results obtained in this study, the following conclusions can

be presented:

1. Addition of waste plastic fibers with different volume ratios to gap-graded concrete slightly increases

the compressive strength up to (Vf=1%) at ages 7, 28, and 56 days comparing with the original mix. The

maximum values of increasing were about (3%) for 28 days and (7.5%) for 56 days age for WPFRC mix

with (Vf=1%) .

2. Addition of waste fiber with different volume ratios to gap-graded concrete increases the splitting tensile

strength for WPFRC mixes at ages 28, and 56 days comparing with the original mix. The max. value of

increasing is (57%) for 28 day while (18%) for 56 days age for the mix with (Vf=1%) of waste plastic fiber

to . Another mixes also show increasing in the splitting tensile strength but not as (1%) percentage.

3. A significent improvement in the low velocity impact resistance of all gap-graded mixes modified with

waste plastic fibers over reference mix. The increase in the waste plastic fibers percentage gives higher

number of blows at both first crack and failure comparing with reference mix. The amount of increasing

varied from (128.5% ) at (Vf= 0.5%) to (328.6%) for (1.5%) volume ratio at failure.

4. Results of this study open the way to use of waste plastic for developing the performance properties of

gap-graded concrete and extension in studying the hole properties of gap-graded concrete containing these

kind of fibers.

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ACKNOWLEDGMENT

I would like to express my extreme and very special thanks and appreciation to

Dr. Fuhi Li - Department of Civil Engineering Material - School of Civil

Engineering/Southwest Jiaotong University for his assistance in preparing samples and taking

SEM for these samples.

6. REFERENCES

1-ACI Committe 544, ”State-of-the-Art Report on Fiber Reinforced Concrete”, American

Concrete Institute, Detroit, (ACI 544.R-96), ACI Publication, January 1996, Reapproved (2006):

pp:2-3.

2-Kaiping, Liu ; Hewei, Cheng and Jing, Zhou.”Investigation of brucite-fiber-reinforced

concrete”, Cement and Concrete Research Journal,Vol.(34).2004, pp:1981-1986.

3-Song, P.S., Hwang, S. and Sheu, B.C.” Strength properties of nylon- and polypropylene-fiber-

reinforced concretes”, Cement and Concrete Research Journal,Vol. 35 (2005) pp:1546– 1550.

4-Xu, Boa, Toutanji, Houssam A. and Gilbert, John Gilbert, “Impact resistance of poly(vinyl

alcohol) fiber reinforced high-performance organic aggregate cementitious material”, Cement

and Concrete Research Journal,Vol. 40 (2010),pp: 347–351.

5- Senthil, Kumaran ; Lakshmipathy, G. M. and Mushule, Nurdin ,“ Analysis of the Transport

Properties of Tyre Fiber Modified Concrete”, American Journal of Engineering and Applied

Sciences,Vol. 4 (3), 2011,,pp: 400-404.

6- Alhozaimy, Abdulrahman M. ,” Fiber Reinforced Concrete using Recycled Plastic”, Final

Research Report No. 425/47, King Saud University, College of Engineering, Research Center,

July 2006, p-45.

7- Yadav, Ishwar Singh, ”Laboratory Investigations of the Properties of Concrete Containing

Recycled Plastic Aggregate”, Thesis report, Civil Engineering Department, Thapar University,

MAY 2008 , p-92.

8- Ismail, Zainab Z. and AL-Hashmi, Enas A. ,” Use of waste plastic in concrete mixture as

aggregate replacement”, Waste Management Journal, Vol.(28),2008, pp:2041–2047.

9-Iraqi standard specification, (1999),”Portland Cement”, No(5).

10- B.S. 882, “Specification for Aggregate from Natural Sources for Concrete ”, British

Standards Institution, 1992.

11- ASTM C-192. “Standard Practice for Making and Curing Concrete Test Specimens in the

Laboratory", 1988.

12-B.S. 1881, Part 116, ”Method for Determination of Compressive Strength of Concrete Cubes",

British Standards Institution, 1989,3pp.

13-ASTM C496-05. ”Splitting Tensile Strength of Cylindrical Concrete Specimens. American

Society of Testing and Material International . ASTM Standard, Philadephia, Vol. 04-02.2005.

14. Dharani.N, Ashwini.A, Pavitha.G and Princearulraj.G, “Experimental Investigation on

Mechanical Properties of Recron 3s Fiber Reinforced Hyposludge Concrete”, International

Journal of Civil Engineering & Technology (IJCIET), Volume 4, Issue 1, 2013, pp. 182 - 189,

ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316.

15. Dr. Prahallada.M.C, Dr. Shanthappa B. C and Dr. Prakash. K.B., “Effect of Redmud on the

Properties of Waste Plastic Fibre Reinforced Concrete an Experimental Investigation”,

International Journal of Civil Engineering & Technology (IJCIET), Volume 2, Issue 1, 2011,

pp. 25 - 34, ISSN Print: 0976 – 6308, ISSN Online: 0976 – 6316.