Technical seminaron

Uses of Rubber modified bitumen and

Crumb rubber modified bitumenBy

G.S.NISHANK09B91A0124

Introduction

•Bitumen is a black liquid or semisolid form of petroleum which is highly viscous and sticky.•Naturally occurring bitumen is also known as crude bitumen from which refined bitumen is obtained.

•The word bitumen is also known asasphalt which is derived from the French word asphalte and it is also known as moom in persian language.

•Bitumen consists 80% of carbon,15% of hydrogen and the remaining 5% is the combined mixture of oxygen,sulphur , nitrogen and other trace elements

•It is non-crystalline in nature and is soft when hot and hard when cool.

What is asphalt…?

•Asphalt is a mixture of aggregates, binder and filler, used for constructing and maintaining all kind of roads, parking areas etc.• Aggregates used for asphalt mixtures are crushed rock, sand, gravel or slags. Bitumen helps in binding these aggregates into a cohesive mixture .•This gives the pavement the ability to distribute the loads of the traffic before it arrives at the formation level

Why Do We Modify Asphalt?

Unmodified asphalt can be sensitive to•Temperature variations•Brittle in cold temperatures•Thermal Cracks•Softens in high temperatures•Rutting and surface deformations•Modification makes asphalt more temperature stable

Methods of modifying asphalt• Air blowing • Flux oils• PPA- polyphosphoric acid• Crumb rubber derived from scarp tyres• SBR latex• SBS- styrene butadiene styrene

Uses of asphaltAlthough asphalt is mainly used for paving roads, it can also be used for various other purposes such as:

• Transportation (e.g. roads, railway beds or airport runways, taxiways, etc.)

• Recreation (playgrounds, bicycle paths, running tracks, tennis courts...)

• Agriculture (barn floors, greenhouse floors...) Industrial (ports, landfill caps, work sites...)

• Building construction (floorings...)

Common types of bitumen

Generally bitumen is mainly classified into four typesas follows•crumb rubber modified bitumen •natural rubber modified bitumen•polymer modified bitumen•bitumen emulsion

Rubber modified bitumen•Natural rubber is melted and is mixed with bitumen and other aggregates such that it binds the material together.

•It improves the resistance of roads against the wheels.

•Reduces noise created due to friction.

•This process is a costly affair but has good result.

•Waste rubber can be utilised .

•The Ministry of Road Transport & Highways has recommended the use of natural rubber modified bitumen for the construction of roads.

•The Central Road Research Institute (CRRI) has tested the technology for use of modified bitumen.

•The purpose is not to get rid of tires but to enhance the performance of the binder and mix.•Tires have great engineering properties, they don’tcrack in the cold or melt in the heat. •They have a wider range of performance temperatures thanasphalt.•Make asphalt pavements that perform like tires.

Why rubber is mixed with asphalt?

Tire rubber is an engineering tool to:•Reduce cracking•Increase asphalt content and asphalt filmthickness•Prevent bleeding, flushing, and drain-down•An aid to increase performance life•Save Money in reduced maintenance•Save money in project cost through reducedThicknessIncrease safety and reduce noise

Advantages

Wet Process – Rubber is added to liquid asphaltbefore mixing at the hot plant, rubber is wet beforemixing with aggregates.

Dry Process - Rubber is added at the same timethe asphalt and aggregate are mixed, rubber is drybefore mixing with the aggregate. Substitute for 1-3% of Aggregate by mixing crumb rubber directly with aggregate

Methods of Combining Components into rubber.

Crumb rubber modified bitumen• Crumb Rubber Modified Bitumen is produced by incorporating crumb rubber and other additives compatible with bitumen.•CRMB is prepared in a centrally located state-of-the-art plant equipped with special high shear mixing facility, the first of its kind in our country.

•The black crumb rubber is produced from whole tyre scrap.•It is available from 18 mesh up to 40 mesh.•Crumb rubber powder is totally free from metal, fluff etc.•Its usage is in all tyre compounds and almost all black rubber compounds. •Now tire crumb rubber is being extensively used in road construction. •It is in great demand by hot-mix construction plants as its usage has resulted in better durability & life of roads.

Scrap tyres modified to roads

Advantages•Homogenous product free from perennial problem of phase separation.•Improved adhesion between aggregate and binder•Higher resistance to deformation at elevated pavement temperature•Higher fatigue life of mixes•Delay of cracking and reflective cracking.•Lower susceptibility to daily and seasonal temperature variations

•Improved ageing resistance•Improved resistance to stripping / moisture damage•High Marshall stability•Overall improved performance in extreme climatic and under heavy traffic conditions•Does not require change in construction practices / machinery•Cost effective

Thank you

Any Queries…?