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Volume-4, Issue-2, April-2014, ISSN No.: 2250-0758

International Journal of Engineering and Management Research Available at: www.ijemr.net

Page Number: 232-240

Study of Mechanical Properties of Concrete using Waste Pet Bottle Fibres for the Reinforcement

Aditya Krishna Reddy. K1, Arun Kumar. C2

1M.Tech Scholar, Department of Civil Engineering, SRM University, Chennai, INDIA 2

Assistant professor, Department of Civil Engineering, SRM University, Chennai, INDIA

ABSTRACT

Now-a days research on usage of innovative material in concrete to develop it characteristic has been increased. The main problem of the today’s world is waste disposal. So researchers have to find new ways to reuse of waste material. Plastics waste has become a problem because of its non-degradable property. In plastic wastes a larger portion is shared by a type of plastic known as PET (Polyethylene Terephthalate). These are largely obtained for drink and mineral water bottles. In the present study the use of PET bottle fibres obtained by just cutting the PET bottle without any separate recycling process in concrete matrix is report. The test results of different mechanical properties on concrete specimens like Compressive strength, Split tensile strength, Flexural strength, Young’s modulus of concrete, stiffness, Ultimate load, maximum central deflection for different proportions of fibre are be reported. The specimens are reinforced with fibres made from waste Polyethylene Terephthalate (PET) bottles and added with superplasticizers. In this study the dosage of the fibre are 0.25%, 0.5%, 0.75% by weight of cement and the dosage of the superplasticizers 0.8% by weight of cement. The results are very interesting, especially regarding the interlocking between PET and concrete. Keywords—PET bottle fibre, Plastic, Fibre reinforcement, PET bottle fibre reinforced concrete, Superplasticizer.

I. INTRODUCTION

For few decades there is large production of plastic wastes which are non

Among these plastic wastes the most common waste is POLYETHYLENE TERPHTHALATE most commonly known as PET which is obtained in large quantity from plastic water bottles used as containers of soft drinks and water. Keeping the plastic scourge out of dumps not only extends the life of waste disposal facilities

but is a co

-biodegradable and sometimes harmful. In general these indegradable wastes are used for land filling but with the scarcity of space for it. So researchers have to find a solution for the reuse of this material [1, 4].

2saver as well: for every pound of PET that is recycled instead of using virgin resin, 84 % less energy is used,

It is estimated that total 2,480,000 tons of plastic bottles and jars were disposed of in 2008. According to US

percent. In this present paper study on reuse of PET bottle fibre in the matrix of concrete is reported.

Environmental Protection Agency

Generally Americans drinks more bottled water in the world, purchasing 29 billion bottles every year. The recycling rate for those billions of bottles of water is low which is only about 13 percent where they are turned into products like clothing, carpeting, decks, playground equipment and new containers and bottles. In 2005, approximately 2 million tons of water bottles in U.S used for landfills, according to the National Resources Defence Council (NRDC) [11]

as of 2006, it was estimated that 60 billion PET single-use containers were bought and then 45 billion of these were disposed after use.According to UN, 2006, 10% of the plastic produced every year worldwide was disposed into the ocean. 70% of these waste settles under ocean, where they will never degrade. (UN, 2006).

From the study pervious it is provided that there are many use of plastic in construction material [8, 9]. Now a days concrete is the most extensively used construction material due its long service life, low cost and high compressive strength but the main disadvantage is due to its low tensile strength .To improve the tensile behavior of the concrete matrix generally fibres are introduced into it. Numerous studies are made on various fibres into the concrete. By introducing these PET bottle fibre into concrete it gives with high ductility and high tensile strength but it will reduces the workability .So for using this fibre we need to use chemical admixture like Superplasticizer which improves the workability of concrete.

.

The thermal conductivity of concrete reinforced with PET fibres will be reduced with rubber pieces [10]. It has been noticed that there is an increment in the thermal insulation of the concrete by

233

adding plastic fibres and there is increase in impact resistance [2] and toughness .In the case like laying of road PET fibre are more advantages than steel fibre

[7]In this study this paper the dosage of the fibre are 0.25%, 0.5%, 0.75%. By weight of cement and the dosage of the superplasticizers 0.8% by weight of cement.

Table 1 Mix Proportion of Concrete

Specimen Unit weight in kg/m Water Cement ratio 3 Cement FA CA SP Water

PET 0% PET 0.25% PET 0.5% PET 0.75%

451 603 1173 3.61 158 0.35

II. MATERIALS

A. Concrete Mix: Mix proportions for the concrete made under the guidelines of IS 10262-2009 are indicated in Table 1.Ordinary Portland cement (OPC) with a Specific gravity of 3.11, fineness of 6.3% and cement consistency as 31% is used .Water cement ratio (W/C) of 0.35 is used.

Crushed gravel with maximum size of 20 mm was used for coarse aggregate (CA). They have crushing value as 18.8%, Aggregate impact value as 30.23% and specific gravity of 2.5.Fineness modulus of CA is 6.7

River sand of zone II according to IS 383-1970 was used for fine aggregate (FA) with specific gravity of 2.62 and fineness modulus of 2.78 B. Superplasticizer: Superplasticizer (SP) used is a high graded superplasticizer based on naphthalene, highly recommended for increasing the workability and high early and ultimate strengths of concrete.It is supplied in liquid form. Specific gravity is 1.2.Dosage can be used 0.3 to1.2% by weight of cement. It reduces water content upto 12% to 25%.

In this study superplasticizer dosage of 0.8% by weight of cement is used. As it is observed that byusing higher percentage (.i.e. 1%, 1.2%) the setting time of concrete is increasing .By using higher dosage of superplasticizerit is observed that the time taking to demould the specimen from mould increases (it takes approximately 36 to 40 hours) C. PET bottles: In general PET fibre has been used in the concrete mix in the shape of short strips or the fibres have been obtained after a long and expensive process from the waste bottles, by the surfaces of the fibres have been coated with maleic anhydride grafted polypropylene and then cut into the required fibre length.

But here fibres are obtained without any expensive recycle process, but with simple transversal cuts of the bottles by separating the top and bottom parts of the bottle. The circular fibres perform better than the lamellar ones because they guarantee a higher concrete-fibre adherence also for high stresses.The lamellar fibres have a tendency to slip off.These circular fibres obtained cutting waste bottles perpendicularly to their longitudinal axis

More there fibre was in ‘O’ shape these will improve properties than fibre in the form of strips [7]. In some case fibre are obtain by expensive recycling process [5].

Figure1: PET bottles fibres used

. The fibres have a width of about 5to 7 mm and

diameter of the ring around 10cm and the thickness of the fibre is about 0.6mm. PET bottle fibres are as shown in Figure1. Aspect ratio of the fibre is 69. Tensile strength of the fibre is 178.78 MPa and elongation is 64.7%. The equation (1) is used to determine the fibre aspect ratio taking fibre equivalent diameter into account.

λ= 𝑙𝑙

𝑑𝑑𝑒𝑒= 𝑙𝑙

2×�𝐴𝐴Π

= 𝑙𝑙

2×�𝑏𝑏×𝑐𝑐Π

(1)

III. SPECIMEN DETAILS

In the present study the test results of different mechanical properties on concrete specimens like compressive strength, split tensile strength, flexural strength, Young’s modulus of the concretewith acontent of the fibre as 0%, 0.25%, 0.5%, 0.75% by weight of cement and the dosage of the superplasticizer as 0.8% by weight of cement is reported All the specimens, moulds, concrete mixing, curing and testing are made according to the IS 516:1959

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For determining the compressive strength cube specimens of 150mm× 150mm×150mm are casted. For split tensile strength and Young’s modulus cylindrical specimens of the standard height/diameter ratio of 2 .i.e. Height 300mm and diameter 150mm are used. And for flexural strength prism specimens of 100 mm× 100 mm×500 mm are casted.

To obtain compressive strength, split tensile strength, flexural strength and Young’s modulus the specimens are tested in compressive testing machine and testing apparatus for different test are shown in Figure 3(a), 3(b), 3(c), 3(d) respectively

To determine the mid span maximum deflection, ultimate load andstiffness, a reinforced beam of 150 mm × 200 mm × 1200 mm is casted.Fibres of different

proportion (0%, 0.5%, and 0.75% by weight of cement) is added to the concrete and placed in the mould with reinforcement. The detail of specimen and reinforcement is given in Figure.2.

Figure2: Reinforcement details

(a) (b)

(c) (d)

Figure3: (a) Testing for compressive strength (b) Testing for split tensile strength (c) Testing for Young’s’s modulus (d) Testing arrangement for flexural strength

Table 2 Result of tested specimen for Compressive strength, Split tensile strength, Flexural strength on 7th,14th and 28th

day.

Compressive strength in MPa Split tensile strength in MPa Flexural strength in MPa

7 days 14 days 28days 7 days 14 days 28days 7 days 14 days 28days

PET 0% 39.11 47.9 55.29 2.7 3.32 4.13 3.17 3.83 5.67

PET 0.25% 40.31 49.5 56.49 2.87 3.54 4.34 3.33 4.17 6.33

PET 0.5 % 41.79 50.5 58.22 3.01 3.81 4.72 3.83 4.5 6.5

PET 0.75% 42.59 51.75 59.01 3.14 4.01 5 4.33 5.33 7.67

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Here PET 0%, PET 0.25%, PET 0.5%, PET 0.75 % represents amount of fibre (0% , 0.25%, 0.5% , 0.75 %

weight of cement. Three specimens were for each mix for each days test.

IV. RESULTS AND DISCUSSIONS

A. COMPRESSIVE STRENGTH: Compressive Strength is tested in compression testing machine according to IS 14858:2000.Cube specimens of 150 mm×150 mm×150 mm.Initially to know appropriate amount of superplasticizer mix with 0%, 0.8%, 1%, 1.2% by weight of cement is casted and tested for 7days and results are given Table 3. When used the Superplasticizer amount more than 1%, the setting time of the concrete is affected. So the Superplasticizer dosage of 0.8% of the weight of cement is taken as optimum amount

Table 3 Cube specimen with different dosage of superplasticizer

Cube

7 days Compressive strength in MPa Average

Strength in

M'Pa

Specimen 1

Specimen 2

Specimen 3

With Normal

design mix

34.36 43.82 33.3 37.2

With 0.8% Superplasti

cizer

34.67 42.67 40 39.1

With 1% Superplasti

cizer

32 36.9 36.9 37.18

With 1.2 % Superplasti

cizer

44.08 43.36 38.177 41.9

Figure4: Comparison of Compressive strength

From Table 2 Compressive strength test results of 7days, 14 days and 28days for fibre content 0% to 0.75 % of fibre with 0.8% of superplastizers is obtained. The specimen is tested after curing in water for 7, 14 and 28 days. The results observed that there is very less increase in the compressive strength by increase the amount of fibre which is no considerable..

Compressive strength for 7days is 39.1 MPa, 40.3 MPa, 41.8MPa, 42 MPa for PET 0% PET 0.25%, PET 0.5%, PET 0.75% respectively. For 28 days is 55 MPa, 56.5 MPa, 58.2MPa, 59 MPa for PET 0%, PET 0.25%, PET 0.5%, and PET 0.75% respectively.

B. SPLIT TENSILE STRENGTH: Split tensile strength is tested in compression testing machine. From Table 2 split tensile strength test results of 7days, 14 days and 28days for fibre content 0% to 0.75 % of fibre with 0.8% of superplastizers is obtained. The specimen is tested after curing in water for 7, 14 and 28 days. Split tensile strength is calculated according to IS: 5816-1970.

39.11 40.31 41.79 42.59

47.9 49.5 50.5 51.7554.67

56.4958.22

60.98

30

35

40

45

50

55

60

65

PET 0% PET 0.25% PET 0.5% PET 0.75%

Com

pres

sive

stre

ngth

in M

Pa

Difffrent concrete mixes7 days 14 days 28 days

236

Figure5: Comparison of Split tensile strength

The results indicated that there is 16% increase in the results for PET 0.75% for 7 days and 20% increase in split tensile strength for PET 0.75% for 28 days. Split tensile strength for 7days is 2.7 MPa, 2.87 MPa, 3.01 MPa, and 3.14 MPa and for 28 days is 4.13 MPa, 4.34MPa, 4.72MPa, 5MPa for PET 0%, PET 0.25%, PET 0.5%, and PET 0.75% respectively

The increase in split tensile strength indicated the interaction between fibres and the concrete matrix. Figure 6shows that the specimen of PET 0% is tested when the specimen is divided into two half, but when fibres are introduced into concrete and testedthe depth of the crack through specimen is reduced .There is no breaking of specimen but just a crack.

(a) (b)

(c) (d) Figure6: (a)Specimen after for PET 0 % mix (b) Specimen after for PET 0.25 % mix (c) Specimen after for PET 0.5 % mix (d) Specimen after

for PET 0.75 % mix for split tensile strength. C. FLEXURAL STRENGTH: Flexural strength is tested in compression testing machine

2.72.87

3.013.14

3.323.54

3.814.01

4.134.34

4.724.97

2.5

3

3.5

4

4.5

5

PET 0% PET 0.25% PET 0.5% PET 0.75%

Split

Ten

sile

stre

ngth

Different mixes7 days 14 days 28 days

237

Figure.7 Comparison of Flexural strength

From Table 2 flexural strength test results of

7days, 14 days and 28days for fibre content 0% to 0.75 % of fibre with 0.8% of superplastizers isobtained. Flexural strength is tested as a simple

beam with third point loading according to ASTM C293-02.The

results indicated that there is 35% increase in the results for PET 0.75% for 7 days and 28 days. Flexural strength for 7days is 3.1 MPa, 3.3 MPa, 3.8 MPa, 4.3 MPa and for 28 days is 5.6 MPa, 6.3MPa, 6.5MPa, 6.7MPa for PET 0%, PET 0.25%, PET 0.5%, and PET 0.75% respectively

Figure 8 shows that when the specimen of PET 0% is tested, the specimen is divided into two half but when fibres are introduced into concrete and tested the depth of the crack in to specimen reduced like same as in the case of split tensile strength. As it is known that flexural strength is materials ability to resist deformation under load by increasing the flexural strength deformation of the specimen will also reduce.

(a) (b)

(c) (d)

Figure8: (a)Specimen after for PET 0 % mix (b) Specimen after for PET 0.25 % mix (c) Specimen after for PET 0.5 % mix (d) Specimen after for PET 0.75 % mix for flexural strength.

D. YOUNG’S’S MODULUS: Cylinder specimens of size 150 mm diameter and 300 mm for various mixes were casted then a compressometer is attached to it and test.The specimen is tested for 28 days.

Young’s modulus of the specimen increases by increase in the fibre content. It is observed that Young’s modulus value of PET 0% is 36747.34MPa it increased to43221.51 MPa for PET 0.75%.There is an increase of 17%.

3.17 3.333.83

4.333.83

4.174.5

5.335.67

6.33 6.5

7.67

2.53

3.54

4.55

5.56

6.57

7.58

PET 0% PET 0.25% PET 0.5% PET 0.75%

Flex

ural

stre

ngth

in M

Pa

Differnt concrete mixes

Flexural strength in MPa

7 days 14 days 28 days

238

Figure.4.19 shows the comparison of Young’s modulus values for different proportion of PET fibre. Figure 9, 10, 11, 12 shows stress vs strain

curve of PET0%, PET0.25%, PET0.5%, PET0.75% respectively.

Figure.9 Stress strain curve for specimen of PET 0% Figure.10 Stress strain curve for specimen of PET 0.25 %

Figure.11 Stress strain curve for specimen of PET 0.5% Figure.12 Stress strain curve for specimen of PET 0.75%

E.MAXIMUM CENTRAL DEFLECTION AND ULTIMATE LOAD: The test for reinforced concrete beam is conducted on 7th

Fibres are added in the concrete matrix andplaced into rectangular mould with steel reinforcement.Table 4 gives maximum cental deflection and ultimate load.Maximun central deflection is more for PET 0% and low for PET 0.75%.For ultimate load it is obseved that the highest value is 63743.26N for PET 0.75%. For first crack

happen at 22064N for all mixes with different fibre proportion .Fig 15 gives load vs deflection graph of diffent proportion of PET fibre day after casting

and tested in 2 point loading method as shown in Figure.13,14 .

F. STIFFNESS:Stiffness may be defined as the load required causing unit deflection. The stiffness values of the specimen at ultimate load were presented in the Table 4 shows that the stiffness value. Stiffness increses with increase in the quantity of fibre. In thisstudy highest value is for PET 0.75% which is 10990 N/mm and lowsest for Pet0%which6870.9N/mm.Figure 16 give stiffness vs load graph for differnet content of fibre.

y = 3.7301x + 0.0905

01234567

0.00 0.50 1.00 1.50 2.00

Stre

ss in

KN

/mm

2

Strain × 10-4

y = 3.818x + 0.225

01234567

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60

Stre

ss in

N/m

m2

Strain × 10-4

y = 4.347x + 0.034

0

1

2

3

4

5

6

7

0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60

Stre

ss in

N/m

m2

Strain×10-4

y = 4.268x + 0.26

0

1

2

3

4

5

6

7

0 0.5 1 1.5 2

Stre

ss in

KN

/mm

2

Strain × 10-4

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Table 4 Maximum central deflection in mm and ultimate load in N Stiffness in N/mm for different fibre proportion

Maximum central deflection (mm) Ultimate load (N) Stiffness ( N/mm)

PET 0% 7.8mm 53936.57 6870.901

PET 0.25% 6.85mm 58839.9 8589.23

PET0.75 % 5.89mm 63743.26 10990.21

Figure13:Testing of RCC beam with PET0%

Figure14: Testing of RCC beam with PET 0.75%

Figure 15: Load vs Deflection of R.C.C for different

proportion of fibre

Figure16:Stiffness vs load graph for RCC beam with

different proportion of fibre

V. CONCLUSION The following are the conclusion obtained from the present study

It was seen that the value of compressive strength, split tensile strength, flexural strength increases with increase in the curing time. To improve the workability of concrete , 0.8% dosage of naphthalene based superplasticizer is used.

Compressive strength of specimen is tested for 7, 14, 28 days. For 7 days the compressive strength for PET 0.75% (.i.e. fibre content 0.75% weight of cement) increased by 3.2% compared to PET 0%. For 28 days the compressive strength for PET 0.75% increased by 5% compared to PET 0%. As the 3 % increase in compressive strength is negligible. It is concluded that by increasing in the fibre content, there is no effect on compressive strength.

0

10000

20000

30000

40000

50000

60000

70000

0 2 4 6 8 10

Load

in N

Central deflection in mm

Load vs Deflection

PET 0.75% PET 0.5% PET 0%

0

2000

4000

6000

8000

10000

12000

14000

16000

18000

20000

0 20000 40000 60000 80000

Stiff

ness

in N

/mm

Load in N

Stiffness vs Load

0.75% 0.50% 0%

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Split tensile strength of specimen is tested for 7, 14, 28 days. For 7 days the Split tensile strength for PET 0.75% is increased by 16.2 % compared to PET 0%. For 28 days the split tensile strength for PET 0.75% increased by 20.3% compared to PET 0%.When fibres are introduced into concrete and tested the depth of the crack on the cylinder specimen is reduced.

Flexural strength of specimen is tested for 7, 14, 28 days. For 7 days the flexural strength for PET 0.75% is increased by 35 % compared to PET 0%. For 28 days the flexural strength for PET 0.75% increased by 33 % compared to PET 0%. When the specimen of PET 0% is tested for flexural strength, the specimen is broken completely but when fibres are introduced into concrete and tested, the depth of the crack through the specimen is reduced.

Young’s modulus of specimen is tested for 28 days. For 28 days the Young’s modulus for PET 0.75% increased by 17 % compared to PET 0%.The highest value of Young’s modulus in all mixes is 43211.51 MPa.

Maximum central deflection and ultimate load of reinforced concrete beam specimen with fibres added in concrete is tested for 7 days and the results are reported in Table 4.6. For 7 days the maximum central deflection for PET 0.75% reduced by 24.4 % compared to PET 0%. For 7 days the ultimate load for PET 0.75% increased by 19 % compared to PET 0%.

Stiffness of reinforced concrete beam specimen with fibres added in concrete is tested for 7 days and the results are reported in Table 4.7. For 7 days the Young’s modulus for PET 0.75% increased by 56 % compared to PET 0%.

In the case of ultimate load it is observed the first crack of all mixes occurs at same load but there is increase in the ultimate load which indicates that if there increase in content of fibre increased the resistance of beam against ultimate failure. The fibres used in this study are just directly cut from PET bottles, no need to undergo any costly recycle processes. These fibres are non-corrosive, insulated fibre.

REFERENCES

[1]. M. Batayneh, I. Mari, I. Asi., Use of selected waste materials in concrete mixes, Waste Manage 27(12):1870–6,2007.

[2]. Z.Bayasi, J. Zeng., Properties of polypropylene fibre reinforced concrete,ACI Mater J 90(6):605–10,1997.

[3]. B. Bourdin., Numerical implementation of the variational formulation of brittle fracture. Interfaces Free Bound, 9:411–30,2007.

[4]. Y.W. Choi, D. J. Moon, J. S.Chung, S. K.Cho., Effects of waste PET bottles aggregate on the properties of concrete. Cement Construction, 35(4):776–81, 2005.

[5]. D. Foti., Preliminary analysis of concrete reinforced with waste bottles PET fibres, Construction Building Materials, 25:1906–15, 2011.

[6]. O. Y.Marzouk, R. M.Dheilly, M.Queneudec., Valorization of post-consumer waste plastic in cementitious concrete composites, Waste Manage, 27:310–8, 2007.

[7]. T.Ochi, S.Okubo, K. Fukui., Development of recycled PET fibre and its application as concrete-reinforcing fibre, Cement construction Composite ,29:448–55, 2007.

[8]. R.Siddique, J.Khatib, I.Kaur., Use of recycled plastic in concrete: a review, Waste Manage 28:1835–52, 2008.

[9]. P.Soroushian, J. Plasencia, S.Ravanbakhsh., Assessment of reinforcing effects of recycled plastic and paper in concrete. ACI Mater J 100(3):203–7, 2003.

[10]. B.Yesilata,Y. Isiker, P.Turgut., Thermal insulation enhancement in concretes by adding waste PET and rubber pieces: Construction Building Materials 23:1878–82, 2009.

[11]. (2014) Bio-Tec Environmental [Online]. Available: http://www.goecopure.com/plastic-pollution/

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