One of the main environmental problem today is the disposal of the waste plastics. The use of plastics in various places as packing materials and the products such as bottles, polythene sheets, containers, packing strips etc., are increasing day by day. This results in production of plastic wastes from all sorts of livings from industrial manufacturers to domestic users. To circumvent this pollution crisis, many products are being produced from reusable waste plastics. On the other side, the Indian construction industry is facing problems due to insufficient and unavailability of construction materials. So, we need to search for new construction materials as well as a method to dispose the plastic waste. To find a solution to the above problems, one of them can be used to solve the other. In this experimental study, an attempt has been made to use the waste plastics in concrete and studies have been conducted to focus particularly on the behavior of compression members with various proportions of plastic wastes. The plastics used in this investigation were polythene sheets, raw plastics (raw material used for straw manufacturing), road wastes (waste plastics collected from road sides are melted and shredded) and plastic straw. The above plastic wastes were mixed with cement concrete in various proportions (0.1% to 2%) and test specimens were cast (cubes and columns) to study the behavior of plastic mixed concrete in axial compression.
S. Gowri, Senior Lecturer, and N. Rajkumar, Lecturer, Dept of Civil Engg, Erode Sengunthar Engineering College, Thudupathi, Erode
Plastics are normally stable and not biodegradable. So, their disposal poses problems. Research works are going on in making use of plastics wastes effectively as additives in bitumen mixes for the road pavements. Reengineered plastics are used for solving the solid waste management problems to great extent. This study attempts to give a contribution to the effective use of waste plastics in concrete in order to prevent the ecological and environmental strains caused by them, also to limit the high amount of environmental degradation.
This study attempts to give a contribution to the effective use of domestic wastes (plastics) in concrete in order to prevent the environmental strains caused by them, also to limit the consumption of high amounts of natural resources.
Four types of plastic materials were selected to mix along with the concrete: (1) Polythene Sheet (2) Raw Plastics (3) Road Wastes (4) Plastic Straw to study their behavior in conjunction with concrete. The properties of the materials used in the present investigations were completely studied and the optimum mix of the above plastic materials was found based on their compressive, split tensile, flexural strengths. After finding the optimum mix percentages in compression, RC columns were cast and tested for its compressive strength. From the investigation, the road waste mixed concrete was found to take more loads in compression. Raw plastic mixed concrete as well as plastic straw mixed concrete were also found to give better strength than the reference RC column.
Prabir Das (2004) has suggested that plastics can be used in construction industry at various places. Proper selection of material / grade and suitable design considerations can help to replace many more applications. Lighter weight, design flexibility, part integration, low system cost, very high productivity and improved product appearance are the main features for use of engineering plastics. The engineering thermoplastics and introduction of application specific grades has thrown challenges to conventional materials in the industries. This paper provides all the supports in selecting suitable engineering plastics, process and design for conversion of conventional material to engineering plastics for performance and system cost benefits.
Chandrakaran (2004) has explained a laboratory experimental study carried out to utilize waste plastics (in the form of strips) obtained from milk pouches in the pavement construction. Results of the study indicate that by adding plastic strips in the soil, shear strength, tensile strength and CBR values of the soil increases. In this study, plastic or polythene sheets having thickness of 0.5mm and which are made up of high density are used. Three types of plastic strips were used in this study to act as a reinforcing material. The first one was cut into 20mm x 40mm size, second one was 25mm x 50mm size and the third one was of 30mm x 60mm size. These plastic strips have innumerable advantageous properties like high tensile strength, low permeability etc., These plastic strips act as a good barrier to gases and liquids and are unaffected by cycles of wetting and drying. For all the strips used in this experimental work, an aspect ratio of 2 is maintained.
Vasudevan (2004), in his report has given most useful ways of disposing waste plastics and laying roads have come to light in a research carried out by the Chemistry Department of Thiyagarajar College of Engineering. They have reported that the waste plastics may be used in block making modified light roofing, mastic flooring and polymer reinforced concrete. The novel composition of waste polymer-aggregate blend has been patented. They have suggested that utilization of waste plastics to enhance the binding property is better option than disposing or enforcing a blanket ban on the use of plastics. It has been reported that the per capita use of plastics in India is 3.5 kg, with virgin plastics accounting for 3.1 million tonnes and recycled plastics, one million. The use in Tamilnadu, with over 7000 units manufacturing material is put at 2.4 lakh tonnes per year. The ‘Garbage Culture’ has made disposal of waste plastic a major problem for civic bodies.
Materials and Methods
Plastics Used in the Investigation
- Polythene Sheet
- Road waste
- Raw Plastics
- Plastic Straw
- Polythene Sheet: The polythene sheets are organic polymers containing carbon in addition to hydrogen, oxygen, nitrogen. The thickness of the polythene sheet used in the present investigation was 250 microns.
- Road Waste: These are nothing but the waste plastics found on the road sides, which were collected and heated. After heating the products were cooled and the resultant product was shredded. These shredded plastic products were selected to mix along with concrete. This type of plastics was mentioned as road waste.
- Raw Plastics: The raw materials used for manufacturing the plastic straw were called as raw plastics. These were round shaped plastic granules which were white in color.
- Plastic Straw: These are tubular plastic products used in day today life. These were mixed along with concrete after cutting them along its cross section. Then the cast specimens were de-moulded next day and subjected to curing.
Results and Discussions
Dimensions of the Test Specimens
The column is of size 100 mm diameter and 750mm height. The longitudinal bars of the column consist of 6 nos. of 6mm diameter. The lateral ties of 5mm diameter plain bars placed at 85mm c/c have been used.
|Table 1: Percentage of Addition of Plastics (for RC Columns)|
|S.No||Type of plastic||Percentage of addition
|Weight of plastic added (gm)|
The columns were cast in the vertical position. The reinforcement cage is inserted in to the PVC mould. The cut polythene sheets were arranged in layer by layer in between concrete layers. The other plastic materials like road wastes and raw plastics were weighed to their optimum percentage and mixed with the concrete and then poured in to the mould. The plastic straw was cut along its cross section and arranged in layers in between concrete. The table vibrator is used to achieve better compaction. The next day the specimens were de-moulded and subjected to curing for specified number of days.
After the specified curing period (7 days), the specimens were taken out for testing.
The column specimens cast by using various plastic mixed concrete were tested for its compressive strength. Before testing the columns, the demec points were selected (at 11.25cm, 26.25cm with a gauge length of 15cm) from each end of the column. Steel pellets were attached to the selected demec points on the column to measure the strains. Six dial gauges were placed along the height of the column, three on one side of the column and the rest on the opposite side. Dial gauges were placed at 18.75 cm intervals throughout the length of the column.
Demec points were fixed along the circumference of the column at selected locations. The complete test set-up for testing the RC column is shown in Figure.
The specimens were placed on the Universal Testing machine. The dial gauges were placed on the specified locations. Strain readings were taken with the help of demec gauge. Load was applied on the specimen gradually. Strain reading and deflections were noted at predetermined load levels. The load was applied continuously till the failure of the specimen takes place. The type of failure was noted down carefully.
The calculated strain values for the RC columns are given in the Table 2.
|Table 2 Compressive Strength of Various RC Columns|
|S.No||Reference RC Columns||Polythene Sheet Mixed RC Columns||Raw Plastic Mixed RC Columns||Road Waste Mixed RC Columns||Plastic Straw Mixed RC Columns|
|Load (kN)||Strain x10-3||Load (kN)||Strain x10-3||Load (kN)||Strain x10-3||Load (kN)||Strain x10-3||Load (kN)||Strain x10-3|
|* Ultimate Load|
Load Carrying capacity
From the studies it is evident that the polythene sheet mixed RC columns were found to withstand an average load of 105.5 kN in compression. This was better than the reference RC columns which took an average load of 100 kN.
The comparison of ultimate load carrying capacity of the RC columns with various plastics is given in Table 3.
|Table 3 Comparison of Ultimate and Initial Crack Loads|
|Type of Columns||Reference RC Columns||Polythene Sheet Mixed RC Columns||Road Waste Mixed RC Columns||Raw Plastic Mixed RC Columns||Plastic Straw Mixed RC Columns|
|Ultimate Load (kN)||100||105.5||122.5||108.5||91.55|
|Initial Crack Load (kN)||35||35||102.5||52||45|
The reference RC columns were found to have a maximum strain of 0.2x10-3 at maximum load of 100kN. The variation of strain is uniform with the increase in load. The polythene sheet mixed RC columns were found to have a maximum strain of 2.67x10-3 at maximum load of 105.5kN. The strain was found to increase with slight increase in load. The road waste mixed concrete RC columns have a strain of 0.25x10-3 at a maximum load of 122.5kN. The strain profile was found to have a minimum variation in between the load range of 20 to 60kN. Raw plastic mixed concrete RC columns have a maximum strain of 5.14x10-3 at a load range of 108.5kN. From the observations made, it was found that raw plastics mixed columns have maximum strain when compared with all the other RC columns. Plastic straw mixed RC columns have a uniform strain variation pattern up to initial crack load and the strain increased more with increase in minimum load.
With the judicious analysis done, the following conclusions were arrived
- The optimum mix percentage of the
- Polythene Sheet is found as 0.2%
- Raw Plastic granule is found to be 0.25%
- Road Waste is found to be 1.25%
- Plastic Straw is found to be 0.1%
- Out of the above four materials Road waste gives better results in compression as well as in flexure (for plain concrete specimens)
- When the Plastic Straw is mixed with concrete it can be used for concrete work of less importance. For example foot path kerbs, pavement blocks etc.,
- The behavior of RC columns mixed with different plastic materials is more or less similar
- The RC columns with Road Waste mixed concrete shows a marginal increase in the ultimate load carrying capacity than that of the reference RC column
- The RC columns with Plastic Straw mixed concrete shows less lateral deflection as compared with other type of plastic materials
- Agarwal, 2004, “Sustainable Alternate Building Materials," CE&CR, page 24-28, October.
- Dr. S.Chandrakaran, 2004, Stabilization of Soils using Plastic Strips as Reinforcing Material,” CE&CR, page 62-66, August
- Prabir Das, 2004, “Engineering Plastics: New Generation Products for Building and Construction,” CE&CR, Page 38-40.
- M.Laksmipathy et.al. 2003, “Use of Reengineered Plastic Shreds as Fibers in Road Pavements,” Proceedings of National seminar on “Furistics in Concrete and Construction Engineering,” December 3-5.
- Vasudevan.R, 2004, “Waste Plastic better used than disposed”, The Hindu, Pp 5 19th January.
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