PREPARATION OF SAMPLE FOR MODIFIED BITUMINOUS MIXES

The samples are prepared by adding polyethylene and kerosene with pure bitumen. The amounts of polyethylene and kerosene are added by weight of percentage of pure bitumen separately.

First of all fresh bitumen, without debris and adulterants was collected. The properties of the bitumen were justified. Five bowls for preparing samples was weighed. Hot bitumen was poured in those bowls. The weight of the bitumen was taken. Then polyethylene was weighed with respect to 1%, 2%, 3%, 4%, and 5% weight of the bitumen. The kerosene was also weighed with respect to 1%, 2%, 3%, 4%, and 5% weight of the bitumen. The samples were prepared one after another. At first the bitumen for 1% polyethylene and 1% kerosene content was heated till it fully liquefied and was in a state to dissolve polyethylene and kerosene. The polyethylene bags were gradually left in the bitumen. The softened form of the polyethylene bags was floating on the hot bitumen. But after continuous stirring by steel spoon it was thoroughly mixed with the bitumen. Though the final mixing temperature was not observed but it is assumed that it was near the flash point of the bitumen. There was a little change in the color. This mother sample is kept for further experiments. Thus five samples were prepared with variable polyethylene and kerosene contents. When a test was to be performed the sample was thoroughly heated so that a homogeneous liquid state could be gained and neither precipitation nor floatation nor suspension was observed.

Sample-1. Weight of pure bitumen + 1% polyethylene of pure bitumen + 1% kerosene of pure bitumen (by weight)

Sample-2. Weight of pure bitumen + 2% polyethylene of pure bitumen + 2% kerosene of pure bitumen (by weight)

Sample-3. Weight of pure bitumen + 3% polyethylene of pure bitumen + 3% kerosene of pure bitumen (by weight)

Sample-4. Weight of pure bitumen + 4% polyethylene of pure bitumen + 4% kerosene of pure bitumen (by weight)

Sample-5. Weight of pure bitumen + 5% polyethylene of pure bitumen + 5% kerosene of pure bitumen (by weight).

CHARACTER OF MATERIALS ARE USED IN MODIFIED BITUMINOUS MIXES

Characteristics of Materials used in modified bitumen:

i)          Bitumen

ii)         Polyethylene

i)                    Kerosene

ii)                   Ice

iii)                 Greece

iv)                 Stone aggregate

v)                  Fine aggregate

vi)        Filler materials.

 

Pure Bitumen

i)        Penetration grade: 80/100

ii)       Specific gravity: 1.02

iii)     Ductility value: 100⁺

iv)     Flash point: 290 ⁰C

v)      Fire point: 300 ⁰C

vi)     Softening point: 43 ⁰C

vii)  Solubility: 95.7%

 

Polyethylene

A particular type of polythene bags, transparent in color, mostly representing the low-density polyethylene purchased from the local market is used. Specific gravity of this specimen varies from 0.95 to 0.93.
 

Coarse Aggregate

It was collected from the hump beside Strength of Materials Lab, Transportation Lab, and from site of under construction Computer Science and Engineering building. The white stone aggregate was used with rather mix of black stone. The aggregate was to pass through 20 mm sieve. Other sieves where retained aggregates were collected are   12.5mm, 9.5mm, 4.75mm and 2.36mm.

Fine Aggregate

Fine aggregate of grade 2.36mm passing and retained at 600mm, 300mm, 150mm, and 75 mm. It was collected from the construction site of new student hostel.

Mineral Filler

It was the residuals received after sieving the fine aggregate in the soil lab by mechanical shaker. It was passed through 75mm sieve. 

INTRODUCTION OF BITUMINOUS MIXES

Bituminous mixes are most commonly used all over the world in pavement construction. Under normal circumstances, conventional bituminous materials if designed and executed properly perform quite satisfactorily. But for special applications like roundabouts or where traffic is extremely heavy, stiffer mixes are required which can have larger fatigue life and more resistance to permanent deformation. It has been found from many researches that the strength of the paving mixes can be enhanced by use of a binder formed by modifying available bitumen with certain additives like sulphur and organic polymers. The modified polymers also improve temperature susceptibility and viscosity characteristics and help alleviating some common problems like bleeding of binder during peak summer temperature and stripping of aggregate in moisture prone areas. The polymers used for modification of bitumen for paving purposes are generally styrene­-butadiene-styrene copolymer, styrene-butadiene rubber, latex, ethylene vinyl acetate copolymer, polyethylene, polypropylene, etc. Most of these polymers, besides being costly, are not available very commonly. Due to these reasons reclaimed rubbers mainly in the form of used tires have been found to perform satisfactorily for years. Keeping the above things in mind, it was felt that an effort can be made to use some material which besides being available easily, is very cheap, or even better, if it is waste material. From this point of view, low density polyethylene carry bags have been used for modification of bitumen in the present investigation. Moreover another reason for choosing this topic is that very little papers are found published with this theme.

GENERAL IDEA TO USE POLYETHYLENE AND KEROSENE WITH BITUMEN

Now-a-day a lot of modifications are taking place through out the world to develop the existing highway materials to fulfill the demand of increased vehicles. People are at a trend to innovate something new that can do better than it was. In fact as a part of that modification and innovation it was our endeavor to redouble the strength of bitumen in such a way that can be adopted with our ecological and social condition. Rubber is so long used as an admixture to bitumen and it is performing well in highway pavements. But considering cost and availability it is sometimes hard some to be well managed in this third world country. Where as polyethylene is somehow used in our country at a great amount and it’s a threat to our environmental soundness. Various types of polyethylene products are used in the market and finally they are disposed in the dustbin where it has no use but waste. These polyethylene most of the time become environmental hazard in case of land filling, sewerage line, open places, etc. But if it is reclaimed and used with the bitumen as binder it can be better used. A few publications are found regarding polyethylene how it can be disposed. But its engineering significance is to be properly justified. With this hope the aim of our work is to use reclaimed polyethylene and kerosene as an admixture to bitumen so to keep the environment safe and enhance high quality bituminous mix for the road construction. After extensive experiment in the laboratory it is found that penetration, ductility, flash and fire point value of the modified bitumen decreased at the same time the softening value increased. Hence it can be better used in the warmer regions. The Marshall Stability Test showed higher stability value and lower flow value which proclaims that the modified form of the bitumen can perform higher bearing capacity and lower deformation to the flexible pavement.