Hello, my name is Gilles Gauthier. I'm responsible for the technical coordination and product development at Total Bitumen. Let's start with the modification of bitumen with polymers. In this video, you will find information about the different types of polymers that can be used, and the benefits of polymer-modification. Polymer-modified bitumen or PMBs, generally consists of a blend of a bitumen with a polymer. Polymers are large molecules composed by the addition of many small molecules called monomers into a chain. Two different types of monomers can be combined into a single polymer, which is then called a copolymer. The most common type of polymer used to modify bitumen is a copolymer of polystyrene and polybutadiene. It is usually called SB or SBS. This family of copolymers is called an elastomer because it brings viscosity and elasticity to the bitumen. More than 80% of polymers used in bitumen are SB or SBSs. But there is another type of polymer that can be used in the bitumen industry. It is a copolymer of polyethylene and polyesters like, for instance, vinyl acetate. This family of copolymers is called a plastomer because it brings stiffness and plasticity to the bitumen. There are many different grades of SBS and plastomers that are suitable for bitumen modification. They differ by their properties like, for instance: molecular size, ratio between copolymers, molecular structure. These parameters impact the mechanical properties of the polymer, and therefore the properties it will bring to polymer-modified bitumen. Now let's focus of the main properties brought by the polymer-modification of bitumen: Polymer modification stiffens of bitumen at elevated service temperatures, say around 50 to 70°C. PMBs have higher Ring&Ball temperature and are less sensitive to creep. The resulting asphalt mix will have an improved resistance to rutting or permanent deformation. At very low temperatures, PMBs are less stiff and more flexible than regular bitumen. They have a lower fraass point and a higher toughness. It makes polymer-modified asphalt mixes more resistant to thermal cracking. In other words, PMBs are less sensitive to extreme temperatures. They can be used on a wider range of temperature compared to regular bitumen. - Polymer modification improves binder cohesion. At low and intermediate temperature, bitumen may be too brittle. Under traffic the film of bitumen hold the aggregates together may break, causing the aggregates to come off. This phenomenon is called raveling. PMB have increased cohesion energy: It requires much more energy to break because of their high elasticity or plasticity. As a consequence the asphalt mix will be much less sensitive to raveling. SBS modified bitumen are typically more viscous than regular bitumen. This may become a problem if the viscosity is too high, because the product can no longer be pumped or it will not coat the aggregates properly, or the asphalt mix can no longer be fully compacted. On the other hand plastomer-modified bitumen are much less viscous. Polymer modification improves the binder resistance to aging. Bitumen on the road is subjected to aggressive climatic conditions like oxidation by air, UV light, water, changes in temperatures... All this combined with traffic loads. Over time the bitumen tends to stiffen and come more brittle. In the case of PMB, this aging phenomenon is mitigated, which brings some extra durability to the pavement. Finally, polymer modification improves the resistance to fatigue. Fatigue is the development of cracks by the repetition of loading cycles. It is responsible for the failure of many pavements! PMBs are more resistant to fatigue. They develop damage at a slower pace, bringing extended lifespan to the pavement. Now you now the main properties of PMBs. We will now see more specific PMB technologies also available on the market. The first one is crosslinked PMBs. The crosslinking technology is based on the modification of the polymer structure in the bitumen matrix by adding a crosslinking agent and creating bonds between the polymer chains. The outcome is a complete change of the PMB microstructure, becoming completely homogeneous. This technology has been patented by Total in 1978 and is widely renowned under the brandname Styrelf with three hundred thousand tons sold each year by Total and its licensees over the world. As a consequence, the PMB receives additional outstanding properties of elasticity, resistance to fatigue, raveling, and temperature susceptibility. PMB are essentially a suspension of swollen polymer particles inside a bituminous matrix. This suspension is not always stable and in some cases the polymer tends to separate from the bitumen within a few hours. It is necessary to stir such blends continuously to ensure proper homogeneity. On the other hand, crosslinked PMBs are also naturally storage stable for months. Another technology is offered by reactive terpolymer. Some advance plastomers are available on the market. These polymers are modified with a special chemical containing an epoxy component. This plastomer is more stable in bitumen and brings higher elasticity and extra stiffness to the PMB. Now, let's summarize what you have learnt about polymer-modified bitumen: Polymers used to modify bitumen are either elastomers, typically SBS polymer, or plastomers, typically polyethylene copolymers. PMBs have improved mechanical properties compared to regular bitumen. These properties include lower temperature susceptibility, resistance to fatigue, lower aging, and high cohesion. Finally, Cross linking allows to further improve the performance of SBS modified bitumen. I thank you for your attention.