Polymer Modified Bitumen

Oscar Ellison

Contents of presentation

• Why do we use polymers• What are polymers• History in NZ and internationally• Types and effects of different polymers• Thermoplastic

– Plastomer– Elastomer

• Thermoset and others• The future

Why do we use polymers

• Increase demand from the road network• Search for new ideas and technologies• Polymers are an effective solution

What is required

• Enhance important properties of asphalt• Not detrimental to basic properties• Workable and able to process• Cost effective

What are polymers

• Very large molecules

• Made up of smaller monomers

• Common both in nature and everyday life

• First synthetic polymers created around 1910

• Varying molecules and lengths

The Chemistry: Styrene-butadiene

ButadieneC4H6

StyreneC6H5CH=CH2

Use in New Zealand

• Natural Latex in sealing

• SBS, EVA and PBD in sealing

• SBS and EVA in asphalt

Types of Polymer Used

Thermoplastic

Thermoset

Elastomers

Plastomers

Elastomers

• Natural RubberLong flexible chains

• SBR (Styrene Butadiene Rubber)Random co-polymerHard styrene and rubbery butadieneBoth monomers compatible with bitumen

SBS (Styrene Butadiene Styrene)

• Most commonly used polymer• Block co-polymer

• Entropic – structural• Enthalpic - energy

Plastomers

• EVAEthylene Vinyl AcetateRandom co-polymer Not crossed-linked

Raises stiffness and toughness at low temperatures

Thermoset

• Uncommon• Epoxy, Polyurethane• Once cured are not affected by temp• Difficult to handle• Created in situ – cross linked polymer network• Increased stiffness, rutting resistance, fuel resistance

• Embrace the use of polymers• Sustainability etc. peak oil• Price of bitumen trending upwards need to find ways to

reduce cost. Polymers can do this. Thinner layers etc. • New polymers. New technologies for mixing.• New thinking…