Bitumen Modified With Styrene Butadiene Styrene thermoplastic For Roofing Application

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Ms. Chinkal Patel – M.E. Chemical, GCPC , Gandhinagar
Prof. Rupande Desai – Asst. Professor of Rubber Technology, L. D. College of Engineering, Ahmedabad
Dr. P. J. Gundaliya – Asst. Professor of Civil Engineering, L. D. College of Engineering, Ahmedabad

In the Past, bitumen was used to waterproof roofs. The roof crack reflected through to the surface of each successive bitumen patch. The cracking problem solve if incorporated rubber in next round of patching. Roofing is a past or we also say that present waterproof barrier of environment & Human Effectiveness.

The primary reason for using bituminous rubber is that it provides significantly improved engineering properties over conventional grade bitumen.

Bitumen interact with SBS rubber are produce bitumen rubber at elevated temperatures, under high agitation to promote high physical interaction of bitumen binder and rubber constituents. After Practical evolution between Bitumen & SBS Rubber, increase Flexibility & High Tensile strength & also reduce crack formation. All Fundamentals of bituminous roofing have been received carefully.

Bitumen rubber binders can be engineered to perform in any type of climate. Responsible bitumen rubber binder designers usually consider climate condition.


The modification of Roofing material with SBS polymers has been a major factor in improving the quality and performance of roofing materials for flat roofs to become reputable and inspire public confidence for waterproofing of flat or slightly inclined roofs. Its also new concept for SBS thermoplastic with bitumen to modified for roofing application.

In Paper also include comparison value bitumen vs. modified bitumen with SBS rubber. Improvement in physical properties of bituminous rubber also seen with practical evaluation. The technology is environment viable. Modified Bitumen will be a possible solution particularly during condition like heavy rainfall areas, areas under hot weather conditions, less maintenance, high performance job and various locations like airfields, dramatic transformation, better performing building.

In British English, the word ‘Bitumen’ refers to a mixture of mineral aggregate and bitumen (or tarmac in common parlance). The word ‘tar’ refers to the black viscous material obtained from the destructive distillation of coal and is chemically distinct from bitumen. Bitumen is a black, oily, viscous material that is a naturally-occurring organic byproduct of decomposed organic materials. Also known as bitumen or tar, bitumen was mixed with other materials throughout prehistory and throughout the world for use as a sealant, adhesive, building mortar, incense, and decorative application on pots, buildings, or human skin.

The primary function of a roof is to present a waterproof barrier of lasting effectiveness. Flat or slightly inclined roofs have proven to be highly space economical and have therefore been applied in commercial buildings over many years. Flat roofs have now also gained acceptance in the housing market, although perception is influenced by the bad performance of early flat roofs.

The Bitumen Rubber is produce at elevated temperatures (>=180°C), under high agitation to promote the physical interaction of the bitumen binder and rubber constituents, and to keep the rubber particles suspended in the blend.

Composition: Bitumen is a complex mixture of hydrocarbons. It can be derived from a straight distillation of a single crude oil. However, it is usually a combination of the heavier products from different processes in a refinery, blended to obtain the right specification. Because of its complexity, the composition is expressed by determining the relative amounts of classes of molecules, asphaltenes and maltenes.1


Modifier: Modified bitumen generally use a traditional waterproofing medium — asphalt — modified with atactic polypropylene (APP), styrene butadiene styrene (SBS), synthetic rubber or other agents that create a uniform matrix that enhances the physical properties of the asphalt. SBS and APP are the most common bitumen modifiers. The modification of roofing material with SBS polymers has been a major factor in improving the quality and performance of roofing materials for flat roofs to become reputable and inspire public confidence for waterproofing of flat or slightly inclined roofs.



Flow Diagram of Manufacturing Process of Bitumen Rubber
Flow Diagram of Manufacturing Process of Bitumen Rubber

1. Proven track record of performance
2. Superior waterproofing characteristics
3. Increase Flexibility2
4. Wide choice of top-surfacing, including “Cool Roofing” options
5. Reduce Flushing
6. With insulation, provides an even better-performing building component
7. High tensile-strength2
8. Available as part of a fire, wind, and/or hail rated roofing system
9. Improved surface texture
10. Competitive life-cycle cost2
11. Available with flame-free
12. Long-term warranties are available with many MB systems
13. Reduce permanent deformation such as rutting
14. Reduce crack formation
15. Reduce low temperature thermal stress cracking2
16. Improve shear resistance allowing thinner layers to be applied
17. Reduce fretting and stripping
18. Increase a roof life.
19. Increase Abrasion Resistance

1. No movement capability.

2. Debonding of membrane where vapour pressures exceed bond strength. This is a particular problem with sheet applied adhesive membranes where vapour gets trapped.3

3. Mobilization costs for bituminous rubber production equipment. For large projects, this cost can be spread over enough tonnage so that increased unit price may be offset by increase service life, lower maintenance cost, and reduce lift thickness. For small projects, however mobilization cost is the same, resulting in greater increase in unit price that may not be fully offset.3

4. On exterior applications black surface increases temperature of slab, increasing slab thermal movement and cracking.3

5. In the temperate climate of India some of the roofs are exposed to sun’s rays from sunrise to sunset and
much of the sunlight strikes the roof surfaces at the steep angle. A dark roof coated by bitumen can attain a very high surface temperature and in addition the reflected radiation from adjacent surface can raise the surface temperature much above than attained by direct radiation.

General Application
Since a bituminous mix prepared with modified bitumen has a higher stiffness modulus, enhanced fatigue life, better resistance to creep and higher indirect tensile strength. They are also used as Stress Absorbing Membrane (SAM) for sealing of cracks as well as interim overlay for preventative maintenance or Stress Absorbing Membrane Interlayer (SAMI) for delaying reflection cracking. Modified bitumen performs better than ordinary bitumen in high rainfall areas and in situations. Due to their better creep resistance properties, they can also be used at busy intersections, bridge decks and roundabouts for increased life of the surfacing.4

Polymer modification of the bituminous roofing material had a major environmental impact, by increasing the roofs lifetime, reducing the number of layers required, and reducing the use of liquid bitumen and traditionally associated noxious emissions because of overheating. The roofing felt is a minor element of the total environmental impact of a building, but despite that, pressure will continue to improve the components’ environmental performance.

Further weight optimization through a further reduction in the number of applied layers together with enhancements of the material itself will be one environmentally-appropriate approach.

Close proximity of “green space” is another important improvement of the environment that becomes possible. The use of new materials allows the construction of reliable and long lasting green roofs with plants and trees growing in a soil layer on top of the roof.


The Tests to be performed on Bitumen, modified bitumen and bituminous mix using Conventional bitumen and modified bitumen. They include conventional tests and non-conventional tests. The conventional and non-conventional tests of modified bitumen were carried out at Transportation Laboratory of Civil Engineering Department at L.D. College Engineering, Ahmedabad.

Conventional Test5 :
1. Penetration test
2. Softening Point test
3. Flash & Fire Test

Non-Conventional Test5:
1. Ductility Test
2. Gravity Test







Improvements of Engineering Properties
Improvement of engineering properties of bituminous rubber composites are following:
1. The Penetration of bituminous rubber decrease when added SBS rubber increases. By adding 4% of rubber
concentration measured by weight of bitumen, the penetration decrease from 80/100 to 60/70.

2. The softening point of bituminous rubber increase when the percentage of SBS rubber increases. This enables bitumen to resist deformations at high temperature conditions.

3. The flash and fire points of bituminous rubber are tested to ensure the safe use of the material. From
the experiment although flash and fire points increase with increase amounts of SBS rubber, they still higher than the critical temperature inside the pug mill.

4. The ductility of the bituminous rubber increase rapidly with added SBS rubber until the percentage reaches 4 % when the value remains almost constant.

5. The specific gravity of rubber bitumen increase when the percentage of added rubber increases.

Flat roofs have now become accepted as a reliable and lasting roof construction solution for commercial and
residential buildings. This has been achieved because high quality roofing materials, such as SBS polymer modified roofing felts, have long been used and applied in a professional fashion.

Economical Point of view:
Price of Bitumen: 33,000/tonne
Price of Styrene – Butadiene – Styrene Thermoplastic: 1,50,000 – 2,30,000/ tonne

So, SBS price also high compare to bitumen and also production rate is low in India, it’s not easily available
in market.

In Penetration value we get approx 10 % reduction, softening point value increase approx 17%, Fire point
increase approx 11 %, Flash point increase approx 6%, ductility value also increase approx 27%, They all value considered as basis on without adding SBS in bitumen(0% SBS) value.


3. Presentation on “Polymer Modified Bitumen” by Dr. Surendra P. Bhatnagar Tech- Dry (India). Pvt. Ltd.
5. BitVal – Analysis of Available Data for Validation of Bitumen Tests, Bitumen Test Relationship p-167
6. S.K. Khanna, C.E.G. Justo,”Highway material testing”, Nem Chand & Bros, Roorkee, India

We at are thankful to Er. Chinkal Patel for submitting the research paper on “Bitumen Modified With Styrene Butadiene Styrene thermoplastic For Roofing Application” to us. We are sure this would be of great help to all engineers who are looking to explore this topic in further research.

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  • B.Koteswara Rao November 7, 2013 at 3:47 am

    sir i want do project on Bitumen Modified With Styrene Butadiene Styrene. This process having some what environmental impact. pls give some suggestions for that…

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