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USE OF WASTE PLASTICS IN CEMENT CONCRETE

PAVEMENTBy

B.V. KIRAN KUMAR* and P.PRAKASH***Lecturer in Civil Engineering, Dayananda Sagar College of Engineering, Kumaraswamy Layout,

Bangalore-560078, Karnataka, India. E-mail: kiran_kumarbv@yahoo.com** Senior Lecturer in Civil Engineering, Dayananda Sagar College of Engineering, Kumaraswamy

Layout, Bangalore-560078, Karnataka, India. E-mail: prakash.dsce@gmail.com

ABSTRACTDue to rapid industrialization and urbanization in the country lot of infrastructure

developments are taking place. This process has in turn led questions to mankind to solve theproblems generated by this growth. The problems defined are acute shortage of constructionalmaterials, increased productivity of wastes and other products. Usually M20 concrete is used formost of the constructional works, hence in this project M20 concrete is taken and waste plastics isused as modifier. Modifier was added in percentage such as 2%, 4%, 6%... in order to replace thesame amount of cement and sand. Tests were conducted on coarse aggregates, fine aggregates,cement and modifiers (waste plastics) to determine their physical properties.

Cubes were casted and tested for 1, 3, 7, 14 and 28 day’s strength. These testsrevealed that the optimum modifier content was found to be 5% by weight of cement and sand.

The studies revealed that the optimum modifier content was 5% and the strength wasfound to be two times greater than the plain cement concrete. The concrete works using modifiercan be used for construction of Rigid Pavements which leads to decrease in the overall thicknessof the pavement.

Keywords: Waste Plastics, M20 Plain Cement Concrete

1.0 INTRODUCTION

As the world population grows, so do the amount and type of wastes being generated.Many wastes produced today will remain in the environment for hundreds and perhaps thousandsof years. The creation of non-decaying waste materials, combined with a growing consumerpopulation, has resulted in a waste disposal crisis. One solution to this crisis lies in recyclingwastes into useful products.

Research into new and innovative use of waste materials being undertaken world-wideand innovative ideas that are expressed are worthy of this important subject. Many highwayagencies, private organizations and individuals have completed or are in the process of completinga wide variety of studies and research projects concerning the feasibility, environmental suitabilityand performance of using waste plastics in highway construction. These studies try to matchsocietal need for safe and economic disposal of waste materials with the help of environmentalfriendly highway industries, which needs better and cost-effective construction materials.

Failure due to fatigue cracking of flexible pavements decreases the load spreadingcharacteristics of bituminous layers. They allow the rain water to percolate to the base, sub-baseand the sub-grade, as a result, complete destruction of pavements takes place, if timelymaintenance is not taken up. With the increase in vehicular volume, there is an increase in the

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cost of construction and the maintenance of the pavements. So, the highway engineers,designers and paving contractors have been looking for the new concept of using waste plasticsin cement concrete pavements. These pavements are less susceptible to rutting, minimumfatigue or thermal cracking, low stripping due to moisture. It offers greater durability, little or noimpact on processing and also produces environmental friendly roads that last longer and costsless.

1.1 General

Definition of plastics: A material that contains one or more organic polymers of large molecularweight, solid in its finished state and at some state while manufacturing or processing intofinished articles, can be shaped by its flow, is termed as “Plastics”.

Types of plastics:

♦ Thermosets.♦ Elastomers.♦ Thermoplastics.

Resins:

Resins are solid or semi-solid materials, light yellow to dark brown in colour, composed ofCarbon, Hydrogen and Oxygen. Resins occur, naturally in plants and are common in pines andfirs, often appearing as globules on the bark. Synthetic resins such as Polystyrene, Polyesters andAcrylics are derived primarily from petroleum. Resins are widely used in the manufacture oflacquers, varnishes, plastics, adhesives and rubber.

Various Resins of Plastics:

♦ Polyethylene Terephthalate (PET, PETE)♦ Density Polyethylene (HDPE)♦ Vinyl (Poly Vinyl Chloride or PVC)♦ Low Density Polyethylene (LDPE)♦ Polypropylene (PP)♦ Polystyrene (PS)

Sources of Generation of Waste Plastics

Household: Carry bags, bottles, containers and trash bags.Health and Medicare: Disposable syringes, glucose bottles, blood, Intravenous tubes, catheters

and surgical gloves.Hotel and Catering: Packaging items, Mineral water bottles, Plastic plates, Glass etc.

1.2 Why Use Plastics?

Polymers have a number of vital properties, which exploited alone or together, make a significantand expanding contribution to constructional needs.

♦ Durable and corrosion resistant.♦ Good Insulation for cold, heat and sound saving energy and reducing noise pollution.♦ It is economical and has a longer life.♦ Maintenance free (such as painting is minimized)♦ Hygienic and clean

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♦ Ease of processing / installation♦ Light weight

1.3 Source of Employment in the Management of WastePlastics:Plastic recycling is taking place on a significant scale in India. As much as 60% of both

industrial and urban plastic waste is recycled. People in India have released plastic wastes haveimmense economic value, as a result of this, recycling of waste plastics plays a major role inproviding employment, resulting in economic development of the country. Indian constructionindustry creates lot of employment opportunities and accounts for major portion of the capitaloutlay in successive 5-year plans of our country. The projected investment in this industrialsector continues to show a growing trend.

Plastic waste is bulky, heavy and unsuitable for disposal by incineration or compostingwhich result in polluting the environment, posing number of problems for the well being of humanrace and resulting in hazardous diseases.

Apart from mounting problems of waste management, other reasons which supportadoption, reuse or recycling strategy are:

1. Reduced extraction of raw materials.2. Reduced transportation cost.3. Reduced environmental impact and improved profits.

Above all, the fast depleting reserves of conventional natural aggregate has necessitated the useof recycling or re-use technology, in order to be able to conserve the conventional naturalaggregate for other important works.

1.4 Advantages of Using Waste Plastics as A Modifier

♦ It easily binds to coarse aggregates at medium temperature.♦ It doesn't require any change in road laying practice.♦ The material is available locally in the form of shredded plastic, which is presently treated

as a waste.♦ The process makes use of used plastic bags in shredded form. The disposal of used

plastics, which is an environmental problem, is thereby eliminated.

1.5 Objectives of Study

2. To find properties of Coarse, Fine Aggregates and Cement.3. To find out physical properties of Waste Plastics (Modifier)4. To conduct mix design as per IS: SP 23-1982(1).5. To find out Optimum Modifier Content (OMC).6. To cast both plain and modified cement concrete beams and subject it to fatigue loading.7. To study the effect of temperature on both plain and modified cement concrete beams

subjected to fatigue loading.

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Type of aggregate Coarse FineSpecific gravity 2.60 2.70

Water absorption 0.50 % 1.0 %

Free (surface) moisture Nil (absorbedmoisture also nil) 2.0 %

Aggregate Impact Value 18.57 % -----Aggregate Crushing Value 17.88 % -----

Los–Angeles Abrasion Value 23.60 % -----

Specific gravity 3.15Initial setting time 35 minutesFinal setting time 16 hours

Soundness by (Autoclave method) 0.6

2.0 LABORATORY INVESTIGATIONS

2.1 Aggregates (Coarse and Fine Aggregates)

Selection of aggregates for normal concrete is very important because, various propertiesof aggregates can influence the performance of concrete. Various considerations have to be keptin mind while selecting the materials. Aggregates used in present study, were tested for theirspecific gravity and other properties and results have been tabulated in table 1. The gradationadopted for the mix was as per IS SP: 23-1982(1) Handbook on Concrete Mixes.

Table 1: Physical Properties of Aggregate (2)

2.2 Cement

Ordinary Portland Cement of 43-grade was used as it satisfied the requirements of IS: 269-1969 and results have been tabulated in table 2.

Table 2: Physical Properties of Cement

2.3 Mixing and Curing Water

IS: 456-2000 (Cl. 2.20) covers requirements for water used for mixing and curing ofconcrete. Permissible limits for solids in water as per IS: 456-2000 is given in table 2.3. Themaximum permissible limit of chloride content in water for RCC work has been reduced from 1000mg/lit in IS: 456-1978 to 500 mg/lit in IS: 456-2000. In addition to the requirements given in table2.3, there are requirements given for acidity and alkalinity for water in terms of neutralization testhas to be considered.

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Type High Density Polyethylene(HDPE)

Specific Gravity 1.04Density (g/cc) 0.945 – 0.962

Melting Point (0C) 75 – 100Softening Point (0C) 110

Elongation at Break (%) >500Fineness <2.36 mm

2.4Plastics

Plastic that cannot be degraded further is been powdered into fine particles. Theseplastics consist mainly of High Density Polyethylene (HDPE). Some of the basic properties ofthese plastic are tabulated in table 3.

Table 3: Physical Properties of Plastics

2.5Preparation of Concrete Cubes

Coarse aggregates are heated to a temperature of 750C to 850C. The waste plasticsobtained in powdered form, are added throughout the heated aggregates and thoroughly mixed. Itis then allowed to cool for about two to three hours, this is mixed with cement, fine aggregates andwater to prepare concrete mix, as per IS SP: 23-1982(1).

Now, concrete cubes are casted, which are of standard dimension of 15 x 15 x 15cms.The specimens are kept for curing and tested for its compressive strength on different days (1, 3, 7,14 & 28).

Here, the modifier (waste plastics) is added in known percentages such as, 2, 4, 6, 7 and8 by weight of cement. By conducting compressive strength tests on cubes casted with varyingpercentages of modifier, Optimum Modifier Content was found to be 5%. Further beyond 5 % thespecimens did not show any appreciable gain in strength. The entire process of mix design isshown from figure 5 to 12.

2.6 Repeated Load Test

2.6.1 Details of Repeated Load Testing Equipment

An attempt was made to study the performance of concrete beams which were casted withand without modifier, under repeated loading test setup. These studies were conducted at varioustemperatures between 250C to 600C. A picture of dynamic setup for repeated load testing isshown in the figure 13.

2.6.2 Laboratory Investigations on Repeated Load Testing

Concrete beam specimens of size 100X100X400mm were casted using plastic modifier atOptimum Modifier Content of 5% (by weight of cement). Similarly beams of plain cement concretewere also casted. Then specimens were subjected to repeated loading tests at the rate of 60cycles/min, at various temperatures from 25oC to 60oC. The stress level of half the compressivestrength test value of 5% modified test specimens was applied on plain and modified concretebeams.

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3.0 ANALYSIS AND DISCUSSIONS

In the present investigation it is found that optimum plastic modifier content was 5% byweight of cement. From the test results it was observed that the compressive strength value of theconcrete mix increased with the addition of modifiers. Comparison of the compressive strengthvalues of plain cement concrete and modified cement concrete are shown in the figure 1 and 2. Itis observed that the fatigue life of the plastic modified concrete has increased by a factor of 6.5,3.0 and 2.75 at 250C, 500C and 600C respectively. The graph of fatigue test results on plain andplastic modified concrete beams are shown in figure 3 and 4.

Special aspects:

♦ Whole process is very simple.♦ It needs no new machinery.♦ The waste plastics available in the surrounding area can be used effectively.

3.1 CONCLUSIONS

Looking into the above aspects we come to the conclusions that the waste plastics can beused as a modifier in the cement concrete mix. This modified cement concrete mix is applicable inthe construction of rigid pavements in order to reduce the thickness of the pavement and increasethe durability of the pavement.

• From experimental analysis, we came to conclusion that the compressive strengths ofmodified cement concrete increases by 20% more than that of plain cement concrete.

• The optimum modifier content is found to be 5%.• It is observed that by using 5% of modifier (waste plastics) the fatigue characteris

of modified concrete at temperature 25 0C, 50 0C and 60 0C has increased fatigue strenby 6.5, 3.0 and 2.75 times that of plain cement concrete.

• By using waste plastics as modifier the quantity of cement used can be reduced by 5%and thereby reducing the cost of construction.

• It also helps to avoid the general disposal technique of waste plastics namely landfilling and incineration which have certain burden on ecology.

• The modified cement concrete mix can be used in construction of rigid pavements reduce the thickness of pavement has it can carry more load than plain cement concretcan also be used in construction of small drainage works and concrete tiles of footpathwalkers.

• When used for rigid pavement construction it can withstand fatigue at higtemperatures hence it can be adopted in tropical regions and also reduction in thicknespavement can be achieved which is provided to cater the warping stress.

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4.0 References

(1) IS SP: 23-1982, Handbook on Concrete Mixes. Bureau of Indian Standards, New Delhi.

(2) IS: 456-2000. Plain and Reinforced Concrete Code of Practice. Bureau of Indian Standards,New Delhi.

(3) S.P. Shah. Concrete composites, fiber reinforced. In S. M. Lee (Ed.), Handbook of CompositeReinforcements. VCH Publishers, Inc., New York, New York, 1993, pp. 155 -170.

(4) D.J. Cook. Concrete and Cement Composites Reinforced with Natural Fibers. In D.J. Hannant(Ed.), Proceedings of the Symposium of Fibrous Concrete. The Construction Press, New York,1980, pp. 99 -114.

(5) K. Rebeiz. Recycling Plastics in the Construction Industry. Waste Age, Vol. 23, Feb. 1992, pp.35 -37.

(6) Prakash Parasivamurthy.Study of Waste Plastics as Composite Materials in CementConcrte Construction. Proceedings of Thermec 2006.

(7) IS: 383-1970, Specification for Coarse and Fine Aggregates from Natural Sources forConcrete. Bureau of Indian Standards, New Delhi.

(8) Ministry of Road Transport and Highways (MoRTH), Specification of Road and BridgeWorks (Fourth Revision), Published by IRC, New Delhi, PP-24, 2001.

(9) Laxmi.S. and Huria.S.C. (1998). A Decennial Appraisal of Quality Trends in IndianCements, Proceedings: vol. 4. Sixth NCB, New Delhi.

(10) P.K. Mehta. Concrete Structure Properties and Materials. Prentice-Hall, Inc., EnglewoodCliffs, New Jersey, 1986.

Acknowledgement:

Authors wish to acknowledge the help render by M/s K.K. Waste Plastics Management Pvt.Limited, Bangalore by providing the modifier. Authors also wish to acknowledge the continuoushelp and encouragement provided during project by Dayananda Sagar College of Engineering, K.S. layout, Bangalore-560 078.

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Figure1: Graph Showing Compressive Strength of Concrete

Figure 2: Graph Showing Compressive Strength of Concrete for Various Percentages ofModifiers

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Figure 3: Graph Showing Number of Repetitions of Plain and Plastic Beams

Figure 4: Graph Showing Number of Repetitions of Plain and Plastic Beams atVarious Temperatures

Plain

Plastic

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Figure 5: Picture Showing Aggregates Being Mixed with Modifier

Figure 6: Picture Showing Modified and Virgin Aggregates

Figure 7: Picture Showing Modified Aggregates Being Mixed with Cement and Sand

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Figure 8: Picture Showing Empty Moulds to Cast the Cube

Figure 9: Picture Showing Concrete being Consolidated on Vibratory Table

Figure 10: Picture Showing Cubes being marked after Casting

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Figure 11: Picture Showing Cubes being cured after Casting

Figure 12: Picture Showing Cubes being tested for its Compressive Strength

Figure 13: Picture Showing Repeated Load Testing Apparatus